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mirror of https://github.com/django/django.git synced 2024-12-22 09:05:43 +00:00

Refs #34140 -- Applied rst code-block to non-Python examples.

Thanks to J.V. Zammit, Paolo Melchiorre, and Mariusz Felisiak for
reviews.
This commit is contained in:
Carlton Gibson 2023-02-09 16:48:46 +01:00 committed by Mariusz Felisiak
parent 7bb741d787
commit 534ac48297
120 changed files with 3998 additions and 1398 deletions

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@ -195,7 +195,9 @@ It's difficult to give an official citation format, for two reasons: citation
formats can vary wildly between publications, and citation standards for
software are still a matter of some debate.
For example, `APA style`_, would dictate something like::
For example, `APA style`_, would dictate something like:
.. code-block:: text
Django (Version 1.5) [Computer Software]. (2013). Retrieved from https://www.djangoproject.com/.

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@ -8,7 +8,9 @@ How can I see the raw SQL queries Django is running?
====================================================
Make sure your Django :setting:`DEBUG` setting is set to ``True``.
Then do this::
Then do this:
.. code-block:: pycon
>>> from django.db import connection
>>> connection.queries
@ -17,16 +19,18 @@ Then do this::
``connection.queries`` is only available if :setting:`DEBUG` is ``True``.
It's a list of dictionaries in order of query execution. Each dictionary has
the following::
the following:
``sql`` -- The raw SQL statement
``time`` -- How long the statement took to execute, in seconds.
* ``sql`` - The raw SQL statement
* ``time`` - How long the statement took to execute, in seconds.
``connection.queries`` includes all SQL statements -- INSERTs, UPDATES,
SELECTs, etc. Each time your app hits the database, the query will be recorded.
If you are using :doc:`multiple databases</topics/db/multi-db>`, you can use the
same interface on each member of the ``connections`` dictionary::
same interface on each member of the ``connections`` dictionary:
.. code-block:: pycon
>>> from django.db import connections
>>> connections['my_db_alias'].queries
@ -85,6 +89,8 @@ these options, create a migration with a
``ALTER TABLE`` statements that do what you want to do.
For example, if you're using MySQL and want your tables to use the MyISAM table
type, use the following SQL::
type, use the following SQL:
.. code-block:: sql
ALTER TABLE myapp_mytable ENGINE=MyISAM;

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@ -36,7 +36,9 @@ I'm getting a ``UnicodeDecodeError``. What am I doing wrong?
This class of errors happen when a bytestring containing non-ASCII sequences is
transformed into a Unicode string and the specified encoding is incorrect. The
output generally looks like this::
output generally looks like this:
.. code-block:: pytb
UnicodeDecodeError: 'ascii' codec can't decode byte 0x?? in position ?:
ordinal not in range(128)

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@ -225,7 +225,9 @@ decorator so that they no longer rejects requests. In every other respect
If, for some reason, you *want* the test client to perform CSRF
checks, you can create an instance of the test client that enforces
CSRF checks::
CSRF checks:
.. code-block:: pycon
>>> from django.test import Client
>>> csrf_client = Client(enforce_csrf_checks=True)

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@ -12,7 +12,9 @@ command for the ``polls`` application from the
To do this, add a ``management/commands`` directory to the application. Django
will register a ``manage.py`` command for each Python module in that directory
whose name doesn't begin with an underscore. For example::
whose name doesn't begin with an underscore. For example:
.. code-block:: text
polls/
__init__.py

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@ -35,7 +35,9 @@ later, so be careful to pick a name that won't clash with custom tags and
filters in another app.
For example, if your custom tags/filters are in a file called
``poll_extras.py``, your app layout might look like this::
``poll_extras.py``, your app layout might look like this:
.. code-block:: text
polls/
__init__.py

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@ -2,8 +2,6 @@
How to use Django with Daphne
=============================
.. highlight:: bash
Daphne_ is a pure-Python ASGI server for UNIX, maintained by members of the
Django project. It acts as the reference server for ASGI.
@ -12,7 +10,9 @@ Django project. It acts as the reference server for ASGI.
Installing Daphne
===================
You can install Daphne with ``pip``::
You can install Daphne with ``pip``:
.. code-block:: shell
python -m pip install daphne
@ -24,7 +24,9 @@ Daphne server process. At its simplest, Daphne needs to be called with the
location of a module containing an ASGI application object, followed by what
the application is called (separated by a colon).
For a typical Django project, invoking Daphne would look like::
For a typical Django project, invoking Daphne would look like:
.. code-block:: shell
daphne myproject.asgi:application

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@ -2,15 +2,15 @@
How to use Django with Hypercorn
================================
.. highlight:: bash
Hypercorn_ is an ASGI server that supports HTTP/1, HTTP/2, and HTTP/3
with an emphasis on protocol support.
Installing Hypercorn
====================
You can install Hypercorn with ``pip``::
You can install Hypercorn with ``pip``:
.. code-block:: shell
python -m pip install hypercorn
@ -22,7 +22,9 @@ which runs ASGI applications. Hypercorn needs to be called with the
location of a module containing an ASGI application object, followed
by what the application is called (separated by a colon).
For a typical Django project, invoking Hypercorn would look like::
For a typical Django project, invoking Hypercorn would look like:
.. code-block:: shell
hypercorn myproject.asgi:application

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@ -2,15 +2,15 @@
How to use Django with Uvicorn
==============================
.. highlight:: bash
Uvicorn_ is an ASGI server based on ``uvloop`` and ``httptools``, with an
emphasis on speed.
Installing Uvicorn
==================
You can install Uvicorn with ``pip``::
You can install Uvicorn with ``pip``:
.. code-block:: shell
python -m pip install uvicorn
@ -22,7 +22,9 @@ applications. Uvicorn needs to be called with the location of a module
containing an ASGI application object, followed by what the application is
called (separated by a colon).
For a typical Django project, invoking Uvicorn would look like::
For a typical Django project, invoking Uvicorn would look like:
.. code-block:: shell
python -m uvicorn myproject.asgi:application
@ -41,11 +43,15 @@ Deploying Django using Uvicorn and Gunicorn
Gunicorn_ is a robust web server that implements process monitoring and automatic
restarts. This can be useful when running Uvicorn in a production environment.
To install Uvicorn and Gunicorn, use the following::
To install Uvicorn and Gunicorn, use the following:
.. code-block:: shell
python -m pip install uvicorn gunicorn
Then start Gunicorn using the Uvicorn worker class like this::
Then start Gunicorn using the Uvicorn worker class like this:
.. code-block:: shell
python -m gunicorn myproject.asgi:application -k uvicorn.workers.UvicornWorker

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@ -2,8 +2,6 @@
How to use Django with Gunicorn
===============================
.. highlight:: bash
Gunicorn_ ('Green Unicorn') is a pure-Python WSGI server for UNIX. It has no
dependencies and can be installed using ``pip``.
@ -23,7 +21,9 @@ Running Django in Gunicorn as a generic WSGI application
When Gunicorn is installed, a ``gunicorn`` command is available which starts
the Gunicorn server process. The simplest invocation of gunicorn is to pass the
location of a module containing a WSGI application object named
``application``, which for a typical Django project would look like::
``application``, which for a typical Django project would look like:
.. code-block:: shell
gunicorn myproject.wsgi

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@ -85,7 +85,9 @@ should put in this file, and what else you can add to it.
If you get a ``UnicodeEncodeError`` when uploading or writing files with
file names or content that contains non-ASCII characters, make sure Apache
is configured to support UTF-8 encoding::
is configured to support UTF-8 encoding:
.. code-block:: shell
export LANG='en_US.UTF-8'
export LC_ALL='en_US.UTF-8'
@ -94,7 +96,9 @@ should put in this file, and what else you can add to it.
Alternatively, if you are :ref:`using mod_wsgi daemon mode<daemon-mode>`
you can add ``lang`` and ``locale`` options to the ``WSGIDaemonProcess``
directive::
directive:
.. code-block:: text
WSGIDaemonProcess example.com lang='en_US.UTF-8' locale='en_US.UTF-8'

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@ -2,8 +2,6 @@
How to use Django with uWSGI
============================
.. highlight:: bash
uWSGI_ is a fast, self-healing and developer/sysadmin-friendly application
container server coded in pure C.
@ -48,7 +46,9 @@ uWSGI supports multiple ways to configure the process. See uWSGI's
.. _configuration documentation: https://uwsgi.readthedocs.io/en/latest/Configuration.html
Here's an example command to start a uWSGI server::
Here's an example command to start a uWSGI server:
.. code-block:: shell
uwsgi --chdir=/path/to/your/project \
--module=mysite.wsgi:application \
@ -80,7 +80,9 @@ The Django-specific options here are:
* ``env``: Should probably contain at least :envvar:`DJANGO_SETTINGS_MODULE`.
* ``home``: Optional path to your project virtual environment.
Example ini configuration file::
Example ini configuration file:
.. code-block:: ini
[uwsgi]
chdir=/path/to/your/project
@ -91,7 +93,9 @@ Example ini configuration file::
max-requests=5000
daemonize=/var/log/uwsgi/yourproject.log
Example ini configuration file usage::
Example ini configuration file usage:
.. code-block:: shell
uwsgi --ini uwsgi.ini
@ -99,7 +103,9 @@ Example ini configuration file usage::
If you get a ``UnicodeEncodeError`` when uploading files with file names
that contain non-ASCII characters, make sure uWSGI is configured to accept
non-ASCII file names by adding this to your ``uwsgi.ini``::
non-ASCII file names by adding this to your ``uwsgi.ini``:
.. code-block:: ini
env = LANG=en_US.UTF-8

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@ -30,15 +30,17 @@ connection:
Auto-generate the models
========================
.. highlight:: bash
Django comes with a utility called :djadmin:`inspectdb` that can create models
by introspecting an existing database. You can view the output by running this
command::
command:
.. code-block:: shell
$ python manage.py inspectdb
Save this as a file by using standard Unix output redirection::
Save this as a file by using standard Unix output redirection:
.. code-block:: shell
$ python manage.py inspectdb > models.py
@ -68,7 +70,9 @@ Install the core Django tables
==============================
Next, run the :djadmin:`migrate` command to install any extra needed database
records such as admin permissions and content types::
records such as admin permissions and content types:
.. code-block:: shell
$ python manage.py migrate

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@ -28,7 +28,9 @@ You can install ReportLab with ``pip``:
$ python -m pip install reportlab
Test your installation by importing it in the Python interactive interpreter::
Test your installation by importing it in the Python interactive interpreter:
.. code-block:: pycon
>>> import reportlab

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@ -172,7 +172,9 @@ for gathering static files in a single directory so you can serve them easily.
STATIC_ROOT = "/var/www/example.com/static/"
#. Run the :djadmin:`collectstatic` management command::
#. Run the :djadmin:`collectstatic` management command:
.. code-block:: shell
$ python manage.py collectstatic

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@ -2,8 +2,6 @@
How to install Django on Windows
================================
.. highlight:: doscon
This document will guide you through installing Python 3.11 and Django on
Windows. It also provides instructions for setting up a virtual environment,
which makes it easier to work on Python projects. This is meant as a beginner's
@ -28,7 +26,9 @@ Download the executable installer and run it. Check the boxes next to "Install
launcher for all users (recommended)" then click "Install Now".
After installation, open the command prompt and check that the Python version
matches the version you installed by executing::
matches the version you installed by executing:
.. code-block:: doscon
...\> py --version
@ -60,12 +60,16 @@ environments which we will use for this guide.
To create a virtual environment for your project, open a new command prompt,
navigate to the folder where you want to create your project and then enter the
following::
following:
.. code-block:: doscon
...\> py -m venv project-name
This will create a folder called 'project-name' if it does not already exist
and set up the virtual environment. To activate the environment, run::
and set up the virtual environment. To activate the environment, run:
.. code-block:: doscon
...\> project-name\Scripts\activate.bat
@ -79,7 +83,9 @@ Install Django
Django can be installed easily using ``pip`` within your virtual environment.
In the command prompt, ensure your virtual environment is active, and execute
the following command::
the following command:
.. code-block:: doscon
...\> py -m pip install Django
@ -100,7 +106,9 @@ for some reason this needs to be disabled, set the environmental variable
:envvar:`DJANGO_COLORS` to ``nocolor``.
On older Windows versions, or legacy terminals, colorama_ must be installed to
enable syntax coloring::
enable syntax coloring:
.. code-block:: doscon
...\> py -m pip install colorama
@ -119,7 +127,9 @@ Common pitfalls
* If you are connecting to the internet behind a proxy, there might be problems
in running the command ``py -m pip install Django``. Set the environment
variables for proxy configuration in the command prompt as follows::
variables for proxy configuration in the command prompt as follows:
.. code-block:: doscon
...\> set http_proxy=http://username:password@proxyserver:proxyport
...\> set https_proxy=https://username:password@proxyserver:proxyport

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@ -16,7 +16,7 @@ requests.
When committing a pull request, make sure each individual commit matches the
commit guidelines described below. Contributors are expected to provide the
best pull requests possible. In practice mergers - who will likely be more
best pull requests possible. In practice mergers - who will likely be more
familiar with the commit guidelines - may decide to bring a commit up to
standard themselves.
@ -27,7 +27,9 @@ Selenium. See the `CI wiki page`_ for instructions.
.. _CI wiki page: https://code.djangoproject.com/wiki/CI
If you find yourself checking out pull requests locally more often, this git
alias will be helpful::
alias will be helpful:
.. code-block:: ini
[alias]
pr = !sh -c \"git fetch upstream pull/${1}/head:pr/${1} && git checkout pr/${1}\"

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@ -413,8 +413,6 @@ the ticket database:
Bisecting a regression
======================
.. highlight:: console
A regression is a bug that's present in some newer version of Django but not in
an older one. An extremely helpful piece of information is the commit that
introduced the regression. Knowing the commit that caused the change in
@ -425,11 +423,15 @@ Begin by writing a regression test for Django's test suite for the issue. For
example, we'll pretend we're debugging a regression in migrations. After you've
written the test and confirmed that it fails on the latest main branch, put it
in a separate file that you can run standalone. For our example, we'll pretend
we created ``tests/migrations/test_regression.py``, which can be run with::
we created ``tests/migrations/test_regression.py``, which can be run with:
.. code-block:: shell
$ ./runtests.py migrations.test_regression
Next, we mark the current point in history as being "bad" since the test fails::
Next, we mark the current point in history as being "bad" since the test fails:
.. code-block:: shell
$ git bisect bad
You need to start by "git bisect start"
@ -440,14 +442,18 @@ introduced (i.e. a point where the test passes). Use something like
``git checkout HEAD~100`` to check out an earlier revision (100 commits earlier,
in this case). Check if the test fails. If so, mark that point as "bad"
(``git bisect bad``), then check out an earlier revision and recheck. Once you
find a revision where your test passes, mark it as "good"::
find a revision where your test passes, mark it as "good":
.. code-block:: shell
$ git bisect good
Bisecting: X revisions left to test after this (roughly Y steps)
...
Now we're ready for the fun part: using ``git bisect run`` to automate the rest
of the process::
of the process:
.. code-block:: shell
$ git bisect run tests/runtests.py migrations.test_regression

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@ -396,13 +396,17 @@ Ensure you have the latest point release of a :ref:`supported Python version
that may cause the test suite to fail or hang.
On **macOS** (High Sierra and newer versions), you might see this message
logged, after which the tests hang::
logged, after which the tests hang:
.. code-block:: pytb
objc[42074]: +[__NSPlaceholderDate initialize] may have been in progress in
another thread when fork() was called.
To avoid this set a ``OBJC_DISABLE_INITIALIZE_FORK_SAFETY`` environment
variable, for example::
variable, for example:
.. code-block:: shell
$ OBJC_DISABLE_INITIALIZE_FORK_SAFETY=YES ./runtests.py
@ -515,8 +519,6 @@ this purpose.
Tips for writing tests
======================
.. highlight:: python
Isolating model registration
----------------------------

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@ -25,7 +25,9 @@ Django's `Git repository`_ is hosted on `GitHub`_, and it is recommended
that you also work using GitHub.
After installing Git, the first thing you should do is set up your name and
email::
email:
.. code-block:: shell
$ git config --global user.name "Your Real Name"
$ git config --global user.email "you@email.com"
@ -43,25 +45,33 @@ Setting up local repository
When you have created your GitHub account, with the nick "GitHub_nick", and
`forked Django's repository <https://github.com/django/django/fork>`__,
create a local copy of your fork::
create a local copy of your fork:
.. code-block:: shell
git clone https://github.com/GitHub_nick/django.git
This will create a new directory "django", containing a clone of your GitHub
repository. The rest of the git commands on this page need to be run within the
cloned directory, so switch to it now::
cloned directory, so switch to it now:
.. code-block:: shell
cd django
Your GitHub repository will be called "origin" in Git.
You should also set up ``django/django`` as an "upstream" remote (that is, tell
git that the reference Django repository was the source of your fork of it)::
git that the reference Django repository was the source of your fork of it):
.. code-block:: shell
git remote add upstream https://github.com/django/django.git
git fetch upstream
You can add other remotes similarly, for example::
You can add other remotes similarly, for example:
.. code-block:: shell
git remote add akaariai https://github.com/akaariai/django.git
@ -69,19 +79,25 @@ Working on a ticket
===================
When working on a ticket, create a new branch for the work, and base that work
on ``upstream/main``::
on ``upstream/main``:
.. code-block:: shell
git checkout -b ticket_xxxxx upstream/main
The -b flag creates a new branch for you locally. Don't hesitate to create new
branches even for the smallest things - that's what they are there for.
If instead you were working for a fix on the 1.4 branch, you would do::
If instead you were working for a fix on the 1.4 branch, you would do:
.. code-block:: shell
git checkout -b ticket_xxxxx_1_4 upstream/stable/1.4.x
Assume the work is carried on the ticket_xxxxx branch. Make some changes and
commit them::
commit them:
.. code-block:: shell
git commit
@ -91,14 +107,18 @@ uncomfortable with English, try at least to describe precisely what the commit
does.
If you need to do additional work on your branch, commit as often as
necessary::
necessary:
.. code-block:: shell
git commit -m 'Added two more tests for edge cases'
Publishing work
---------------
You can publish your work on GitHub by running::
You can publish your work on GitHub by running:
.. code-block:: shell
git push origin ticket_xxxxx
@ -154,7 +174,9 @@ repository. Your commit "Added two more tests" would be unhelpful noise.
Instead, we would rather only have one commit containing all your work.
To rework the history of your branch you can squash the commits into one by
using interactive rebase::
using interactive rebase:
.. code-block:: shell
git rebase -i HEAD~2
@ -167,7 +189,9 @@ the editor. A second editor window should open, so you can reword the
commit message for the commit now that it includes both your steps.
You can also use the "edit" option in rebase. This way you can change a single
commit, for example to fix a typo in a docstring::
commit, for example to fix a typo in a docstring:
.. code-block:: shell
git rebase -i HEAD~3
# Choose edit, pick, pick for the commits
@ -180,7 +204,9 @@ commit, for example to fix a typo in a docstring::
If your topic branch is already published at GitHub, for example if you're
making minor changes to take into account a review, you will need to force-push
the changes::
the changes:
.. code-block:: shell
git push -f origin ticket_xxxxx
@ -193,7 +219,9 @@ After upstream has changed
--------------------------
When upstream (``django/django``) has changed, you should rebase your work. To
do this, use::
do this, use:
.. code-block:: shell
git fetch upstream
git rebase upstream/main
@ -225,12 +253,16 @@ easily check what changes you have done.
In this case, do the changes required by the reviewer. Commit as often as
necessary. Before publishing the changes, rebase your work. If you added two
commits, you would run::
commits, you would run:
.. code-block:: shell
git rebase -i HEAD~2
Squash the second commit into the first. Write a commit message along the lines
of::
of:
.. code-block:: text
Made changes asked in review by <reviewer>
@ -238,7 +270,9 @@ of::
- Reworded the docstring of bar()
Finally, push your work back to your GitHub repository. Since you didn't touch
the public commits during the rebase, you should not need to force-push::
the public commits during the rebase, you should not need to force-push:
.. code-block:: shell
git push origin ticket_xxxxx
@ -252,7 +286,9 @@ Working on a patch
One of the ways that developers can contribute to Django is by reviewing
patches. Those patches will typically exist as pull requests on GitHub and
can be easily integrated into your local repository::
can be easily integrated into your local repository:
.. code-block:: shell
git checkout -b pull_xxxxx upstream/main
curl -L https://github.com/django/django/pull/xxxxx.patch | git am

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@ -192,11 +192,15 @@ documentation:
good reason.
* The main thing to keep in mind as you write and edit docs is that the
more semantic markup you can add the better. So::
more semantic markup you can add the better. So:
.. code-block:: rst
Add ``django.contrib.auth`` to your ``INSTALLED_APPS``...
Isn't nearly as helpful as::
Isn't nearly as helpful as:
.. code-block:: rst
Add :mod:`django.contrib.auth` to your :setting:`INSTALLED_APPS`...
@ -219,7 +223,9 @@ documentation:
* To improve readability, use ``.. admonition:: Descriptive title`` rather than
``.. note::``. Use these boxes sparingly.
* Use these heading styles::
* Use these heading styles:
.. code-block:: rst
===
One
@ -258,44 +264,58 @@ Django-specific markup
Besides :ref:`Sphinx's built-in markup <sphinx:rst-index>`, Django's docs
define some extra description units:
* Settings::
* Settings:
.. code-block:: rst
.. setting:: INSTALLED_APPS
To link to a setting, use ``:setting:`INSTALLED_APPS```.
* Template tags::
* Template tags:
.. code-block:: rst
.. templatetag:: regroup
To link, use ``:ttag:`regroup```.
* Template filters::
* Template filters:
.. code-block:: rst
.. templatefilter:: linebreaksbr
To link, use ``:tfilter:`linebreaksbr```.
* Field lookups (i.e. ``Foo.objects.filter(bar__exact=whatever)``)::
* Field lookups (i.e. ``Foo.objects.filter(bar__exact=whatever)``):
.. code-block:: rst
.. fieldlookup:: exact
To link, use ``:lookup:`exact```.
* ``django-admin`` commands::
* ``django-admin`` commands:
.. code-block:: rst
.. django-admin:: migrate
To link, use ``:djadmin:`migrate```.
* ``django-admin`` command-line options::
* ``django-admin`` command-line options:
.. code-block:: rst
.. django-admin-option:: --traceback
To link, use ``:option:`command_name --traceback``` (or omit ``command_name``
for the options shared by all commands like ``--verbosity``).
* Links to Trac tickets (typically reserved for patch release notes)::
* Links to Trac tickets (typically reserved for patch release notes):
.. code-block:: rst
:ticket:`12345`
@ -304,7 +324,9 @@ command-line examples involving ``django-admin``, ``manage.py``, ``python``,
etc.). In the HTML documentation, it renders a two-tab UI, with one tab showing
a Unix-style command prompt and a second tab showing a Windows prompt.
For example, you can replace this fragment::
For example, you can replace this fragment:
.. code-block:: rst
use this command:
@ -312,7 +334,9 @@ For example, you can replace this fragment::
$ python manage.py shell
with this one::
with this one:
.. code-block:: rst
use this command:
@ -368,7 +392,9 @@ In other words, since we only keep these annotations around for two releases,
it's nice to be able to remove the annotation and its contents without having
to reflow, reindent, or edit the surrounding text. For example, instead of
putting the entire description of a new or changed feature in a block, do
something like this::
something like this:
.. code-block:: rst
.. class:: Author(first_name, last_name, middle_name=None)
@ -392,7 +418,9 @@ redundant to do so as these annotations render as "New in Django A.B:" and
"Changed in Django A.B", respectively.
If a function, attribute, etc. is added, it's also okay to use a
``versionadded`` annotation like this::
``versionadded`` annotation like this:
.. code-block:: rst
.. attribute:: Author.middle_name

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@ -2,8 +2,6 @@
How is Django Formed?
=====================
.. highlight:: console
This document explains how to release Django.
**Please, keep these instructions up-to-date if you make changes!** The point
@ -56,7 +54,9 @@ You'll need a few things before getting started:
``you@example.com`` is the email address associated with the key you want to
use.
* An install of some required Python packages::
* An install of some required Python packages:
.. code-block:: shell
$ python -m pip install wheel twine
@ -117,7 +117,9 @@ any time leading up to the actual release:
#. If this is a feature release, ensure translations from Transifex have been
integrated. This is typically done by a separate translation's manager
rather than the releaser, but here are the steps. Provided you have an
account on Transifex::
account on Transifex:
.. code-block:: shell
$ python scripts/manage_translations.py fetch
@ -125,7 +127,9 @@ any time leading up to the actual release:
Sometimes there are validation errors which need to be debugged, so avoid
doing this task immediately before a release is needed.
#. :ref:`Update the django-admin manual page <django-admin-manpage>`::
#. :ref:`Update the django-admin manual page <django-admin-manpage>`:
.. code-block:: shell
$ cd docs
$ make man
@ -135,7 +139,9 @@ any time leading up to the actual release:
and then commit the changed man page.
#. If this is the alpha release of a new series, create a new stable branch
from main. For example, when releasing Django 3.1::
from main. For example, when releasing Django 3.1:
.. code-block:: shell
$ git checkout -b stable/3.1.x origin/main
$ git push origin -u stable/3.1.x:stable/3.1.x
@ -148,7 +154,9 @@ any time leading up to the actual release:
#. If this is the "dot zero" release of a new series, create a new branch from
the current stable branch in the `django-docs-translations
<https://github.com/django/django-docs-translations>`_ repository. For
example, when releasing Django 2.2::
example, when releasing Django 2.2:
.. code-block:: shell
$ git checkout -b stable/2.2.x origin/stable/2.1.x
$ git push origin stable/2.2.x:stable/2.2.x
@ -176,7 +184,9 @@ OK, this is the fun part, where we actually push out a release!
__ https://djangoci.com
#. A release always begins from a release branch, so you should make sure
you're on a stable branch and up-to-date. For example::
you're on a stable branch and up-to-date. For example:
.. code-block:: shell
$ git checkout stable/1.5.x
$ git pull
@ -184,7 +194,9 @@ OK, this is the fun part, where we actually push out a release!
#. If this is a security release, merge the appropriate patches from
``django-security``. Rebase these patches as necessary to make each one a
plain commit on the release branch rather than a merge commit. To ensure
this, merge them with the ``--ff-only`` flag; for example::
this, merge them with the ``--ff-only`` flag; for example:
.. code-block:: shell
$ git checkout stable/1.5.x
$ git merge --ff-only security/1.5.x
@ -214,7 +226,9 @@ OK, this is the fun part, where we actually push out a release!
classifier in ``setup.cfg`` to reflect this. Otherwise, make sure the
classifier is set to ``Development Status :: 5 - Production/Stable``.
#. Tag the release using ``git tag``. For example::
#. Tag the release using ``git tag``. For example:
.. code-block:: shell
$ git tag --sign --message="Tag 1.5.1" 1.5.1
@ -227,7 +241,9 @@ OK, this is the fun part, where we actually push out a release!
#. Run ``make -f extras/Makefile`` to generate the release packages. This will
create the release packages in a ``dist/`` directory.
#. Generate the hashes of the release packages::
#. Generate the hashes of the release packages:
.. code-block:: shell
$ cd dist
$ md5sum *
@ -303,19 +319,25 @@ Making the release(s) available to the public
Now you're ready to actually put the release out there. To do this:
#. Upload the release package(s) to the djangoproject server, replacing
A.B. with the appropriate version number, e.g. 1.5 for a 1.5.x release::
A.B. with the appropriate version number, e.g. 1.5 for a 1.5.x release:
.. code-block:: shell
$ scp Django-* djangoproject.com:/home/www/www/media/releases/A.B
If this is the alpha release of a new series, you will need to create the
directory A.B.
#. Upload the checksum file(s)::
#. Upload the checksum file(s):
.. code-block:: shell
$ scp Django-A.B.C.checksum.txt.asc djangoproject.com:/home/www/www/media/pgp/Django-A.B.C.checksum.txt
#. Test that the release packages install correctly using ``pip``. Here's one
method::
method:
.. code-block:: shell
$ RELEASE_VERSION='1.7.2'
$ MAJOR_VERSION=`echo $RELEASE_VERSION| cut -c 1-3`
@ -340,7 +362,9 @@ Now you're ready to actually put the release out there. To do this:
files).
#. Upload the release packages to PyPI (for pre-releases, only upload the wheel
file)::
file):
.. code-block:: shell
$ twine upload -s dist/*
@ -368,7 +392,9 @@ Now you're ready to actually put the release out there. To do this:
for the previous release. Update djangoproject.com's `robots.docs.txt`__
file by copying entries from ``manage_translations.py robots_txt`` from the
current stable branch in the ``django-docs-translations`` repository. For
example, when releasing Django 2.2::
example, when releasing Django 2.2:
.. code-block:: shell
$ git checkout stable/2.2.x
$ git pull

View File

@ -357,7 +357,9 @@ that's really what happens. ``cd`` to the Django ``tests/`` directory and run:
$ ./runtests.py shortcuts
If the tests ran correctly, you should see one failure corresponding to the test
method we added, with this error::
method we added, with this error:
.. code-block:: pytb
ImportError: cannot import name 'make_toast' from 'django.shortcuts'
@ -407,7 +409,9 @@ Writing Documentation
This is a new feature, so it should be documented. Open the file
``docs/topics/http/shortcuts.txt`` and add the following at the end of the
file::
file:
.. code-block:: rst
``make_toast()``
================
@ -421,7 +425,9 @@ file::
Since this new feature will be in an upcoming release it is also added to the
release notes for the next version of Django. Open the release notes for the
latest version in ``docs/releases/``, which at time of writing is ``2.2.txt``.
Add a note under the "Minor Features" header::
Add a note under the "Minor Features" header:
.. code-block:: rst
:mod:`django.shortcuts`
~~~~~~~~~~~~~~~~~~~~~~~

View File

@ -20,7 +20,9 @@ Get the latest version of Python at https://www.python.org/downloads/ or with
your operating system's package manager.
You can verify that Python is installed by typing ``python`` from your shell;
you should see something like::
you should see something like:
.. code-block:: pycon
Python 3.x.y
[GCC 4.x] on linux

View File

@ -66,7 +66,9 @@ Enjoy the free API
With that, you've got a free, and rich, :doc:`Python API </topics/db/queries>`
to access your data. The API is created on the fly, no code generation
necessary::
necessary:
.. code-block:: pycon
# Import the models we created from our "news" app
>>> from news.models import Article, Reporter

View File

@ -53,7 +53,9 @@ projects and ready to publish for others to install and use.
Your project and your reusable app
==================================
After the previous tutorials, our project should look like this::
After the previous tutorials, our project should look like this:
.. code-block:: text
mysite/
manage.py
@ -256,9 +258,11 @@ this. For a small app like polls, this process isn't too difficult.
#. It's optional, but recommended, to include detailed documentation with your
app. Create an empty directory ``django-polls/docs`` for future
documentation. Add an additional line to ``django-polls/MANIFEST.in``::
documentation. Add an additional line to ``django-polls/MANIFEST.in``:
recursive-include docs *
.. code-block:: text
recursive-include docs *
Note that the ``docs`` directory won't be included in your package unless
you add some files to it. Many Django apps also provide their documentation
@ -291,16 +295,20 @@ working. We'll now fix this by installing our new ``django-polls`` package.
solution (see below).
#. To install the package, use pip (you already :ref:`installed it
<installing-reusable-apps-prerequisites>`, right?)::
<installing-reusable-apps-prerequisites>`, right?):
python -m pip install --user django-polls/dist/django-polls-0.1.tar.gz
.. code-block:: shell
python -m pip install --user django-polls/dist/django-polls-0.1.tar.gz
#. With luck, your Django project should now work correctly again. Run the
server again to confirm this.
#. To uninstall the package, use pip::
#. To uninstall the package, use pip:
python -m pip uninstall django-polls
.. code-block:: shell
python -m pip uninstall django-polls
Publishing your app
===================

View File

@ -76,7 +76,9 @@ work, see :ref:`troubleshooting-django-admin`.
Put your code in some directory **outside** of the document root, such as
:file:`/home/mycode`.
Let's look at what :djadmin:`startproject` created::
Let's look at what :djadmin:`startproject` created:
.. code-block:: text
mysite/
manage.py
@ -224,7 +226,9 @@ and type this command:
$ python manage.py startapp polls
That'll create a directory :file:`polls`, which is laid out like this::
That'll create a directory :file:`polls`, which is laid out like this:
.. code-block:: text
polls/
__init__.py
@ -257,7 +261,9 @@ This is the simplest view possible in Django. To call the view, we need to map
it to a URL - and for this we need a URLconf.
To create a URLconf in the polls directory, create a file called ``urls.py``.
Your app directory should now look like::
Your app directory should now look like:
.. code-block:: text
polls/
__init__.py

View File

@ -381,7 +381,9 @@ We're using this instead of simply typing "python", because :file:`manage.py`
sets the :envvar:`DJANGO_SETTINGS_MODULE` environment variable, which gives
Django the Python import path to your :file:`mysite/settings.py` file.
Once you're in the shell, explore the :doc:`database API </topics/db/queries>`::
Once you're in the shell, explore the :doc:`database API </topics/db/queries>`:
.. code-block:: pycon
>>> from polls.models import Choice, Question # Import the model classes we just wrote.
@ -468,7 +470,9 @@ you aren't familiar with time zone handling in Python, you can learn more in
the :doc:`time zone support docs </topics/i18n/timezones>`.
Save these changes and start a new Python interactive shell by running
``python manage.py shell`` again::
``python manage.py shell`` again:
.. code-block:: pycon
>>> from polls.models import Choice, Question

View File

@ -206,7 +206,9 @@ In the terminal, we can run our test:
$ python manage.py test polls
and you'll see something like::
and you'll see something like:
.. code-block:: shell
Creating test database for alias 'default'...
System check identified no issues (0 silenced).
@ -267,7 +269,9 @@ past:
now = timezone.now()
return now - datetime.timedelta(days=1) <= self.pub_date <= now
and run the test again::
and run the test again:
.. code-block:: pytb
Creating test database for alias 'default'...
System check identified no issues (0 silenced).
@ -376,13 +380,17 @@ it earlier, check it before continuing.
Next we need to import the test client class (later in ``tests.py`` we will use
the :class:`django.test.TestCase` class, which comes with its own client, so
this won't be required)::
this won't be required):
.. code-block:: pycon
>>> from django.test import Client
>>> # create an instance of the client for our use
>>> client = Client()
With that ready, we can ask the client to do some work for us::
With that ready, we can ask the client to do some work for us:
.. code-block:: pycon
>>> # get a response from '/'
>>> response = client.get('/')

View File

@ -9,7 +9,9 @@ and provides introspection. It also maintains a list of available :doc:`models
</topics/db/models>`.
This registry is called :attr:`~django.apps.apps` and it's available in
:mod:`django.apps`::
:mod:`django.apps`:
.. code-block:: pycon
>>> from django.apps import apps
>>> apps.get_app_config('admin').verbose_name

View File

@ -18,9 +18,11 @@ Multiple object mixins
path('objects/page<int:page>/', PaginatedView.as_view()),
* Pass the page number via the ``page`` query-string parameter. For
example, a URL would look like this::
example, a URL would look like this:
/objects/?page=3
.. code-block:: text
/objects/?page=3
These values and lists are 1-based, not 0-based, so the first page would be
represented as page ``1``.
@ -29,7 +31,9 @@ Multiple object mixins
</topics/pagination>`.
As a special case, you are also permitted to use ``last`` as a value for
``page``::
``page``:
.. code-block:: text
/objects/?page=last

View File

@ -3201,7 +3201,9 @@ with an instance namespace corresponding to the name of the Site instance.
So - if you wanted to get a reference to the Change view for a particular
``Choice`` object (from the polls application) in the default admin, you would
call::
call:
.. code-block:: pycon
>>> from django.urls import reverse
>>> c = Choice.objects.get(...)
@ -3214,7 +3216,9 @@ This will find the first registered instance of the admin application
If you want to find a URL in a specific admin instance, provide the name of
that instance as a ``current_app`` hint to the reverse call. For example,
if you specifically wanted the admin view from the admin instance named
``custom``, you would need to call::
``custom``, you would need to call:
.. code-block:: pycon
>>> change_url = reverse('admin:polls_choice_change', args=(c.id,), current_app='custom')

View File

@ -121,7 +121,9 @@ model it represents, or to retrieve objects from that model:
For example, we could look up the
:class:`~django.contrib.contenttypes.models.ContentType` for the
:class:`~django.contrib.auth.models.User` model::
:class:`~django.contrib.auth.models.User` model:
.. code-block:: pycon
>>> from django.contrib.contenttypes.models import ContentType
>>> user_type = ContentType.objects.get(app_label='auth', model='user')
@ -130,7 +132,9 @@ For example, we could look up the
And then use it to query for a particular
:class:`~django.contrib.auth.models.User`, or to get access
to the ``User`` model class::
to the ``User`` model class:
.. code-block:: pycon
>>> user_type.model_class()
<class 'django.contrib.auth.models.User'>
@ -219,7 +223,9 @@ The :meth:`~ContentTypeManager.get_for_model()` method is especially
useful when you know you need to work with a
:class:`ContentType <django.contrib.contenttypes.models.ContentType>` but don't
want to go to the trouble of obtaining the model's metadata to perform a manual
lookup::
lookup:
.. code-block:: pycon
>>> from django.contrib.auth.models import User
>>> ContentType.objects.get_for_model(User)
@ -340,7 +346,9 @@ This will enable an API similar to the one used for a normal
:class:`~django.db.models.ForeignKey`;
each ``TaggedItem`` will have a ``content_object`` field that returns the
object it's related to, and you can also assign to that field or use it when
creating a ``TaggedItem``::
creating a ``TaggedItem``:
.. code-block:: pycon
>>> from django.contrib.auth.models import User
>>> guido = User.objects.get(username='Guido')
@ -351,7 +359,9 @@ creating a ``TaggedItem``::
If the related object is deleted, the ``content_type`` and ``object_id`` fields
remain set to their original values and the ``GenericForeignKey`` returns
``None``::
``None``:
.. code-block:: pycon
>>> guido.delete()
>>> t.content_object # returns None
@ -360,7 +370,9 @@ Due to the way :class:`~django.contrib.contenttypes.fields.GenericForeignKey`
is implemented, you cannot use such fields directly with filters (``filter()``
and ``exclude()``, for example) via the database API. Because a
:class:`~django.contrib.contenttypes.fields.GenericForeignKey` isn't a
normal field object, these examples will *not* work::
normal field object, these examples will *not* work:
.. code-block:: pycon
# This will fail
>>> TaggedItem.objects.filter(content_object=guido)
@ -393,7 +405,9 @@ a "reverse" generic relationship to enable an additional API. For example::
tags = GenericRelation(TaggedItem)
``Bookmark`` instances will each have a ``tags`` attribute, which can
be used to retrieve their associated ``TaggedItems``::
be used to retrieve their associated ``TaggedItems``:
.. code-block:: pycon
>>> b = Bookmark(url='https://www.djangoproject.com/')
>>> b.save()
@ -405,7 +419,9 @@ be used to retrieve their associated ``TaggedItems``::
<QuerySet [<TaggedItem: django>, <TaggedItem: python>]>
You can also use ``add()``, ``create()``, or ``set()`` to create
relationships::
relationships:
.. code-block:: pycon
>>> t3 = TaggedItem(tag='Web development')
>>> b.tags.add(t3, bulk=False)
@ -417,7 +433,9 @@ relationships::
>>> b.tags.all()
<QuerySet [<TaggedItem: django>, <TaggedItem: Web development>]>
The ``remove()`` call will bulk delete the specified model objects::
The ``remove()`` call will bulk delete the specified model objects:
.. code-block:: pycon
>>> b.tags.remove(t3)
>>> b.tags.all()
@ -426,7 +444,9 @@ The ``remove()`` call will bulk delete the specified model objects::
<QuerySet [<TaggedItem: django>]>
The ``clear()`` method can be used to bulk delete all related objects for an
instance::
instance:
.. code-block:: pycon
>>> b.tags.clear()
>>> b.tags.all()
@ -440,14 +460,18 @@ Defining :class:`~django.contrib.contenttypes.fields.GenericRelation` with
tags = GenericRelation(TaggedItem, related_query_name='bookmark')
This enables filtering, ordering, and other query operations on ``Bookmark``
from ``TaggedItem``::
from ``TaggedItem``:
.. code-block:: pycon
>>> # Get all tags belonging to bookmarks containing `django` in the url
>>> TaggedItem.objects.filter(bookmark__url__contains='django')
<QuerySet [<TaggedItem: django>, <TaggedItem: python>]>
If you don't add the ``related_query_name``, you can do the same types of
lookups manually::
lookups manually:
.. code-block:: pycon
>>> bookmarks = Bookmark.objects.filter(url__contains='django')
>>> bookmark_type = ContentType.objects.get_for_model(Bookmark)
@ -491,7 +515,9 @@ Generic relations and aggregation
:doc:`Django's database aggregation API </topics/db/aggregation>` works with a
:class:`~django.contrib.contenttypes.fields.GenericRelation`. For example, you
can find out how many tags all the bookmarks have::
can find out how many tags all the bookmarks have:
.. code-block:: pycon
>>> Bookmark.objects.aggregate(Count('tags'))
{'tags__count': 3}

View File

@ -37,13 +37,17 @@ Creating and Saving Models with Geometry Fields
===============================================
Here is an example of how to create a geometry object (assuming the ``Zipcode``
model)::
model):
.. code-block:: pycon
>>> from zipcode.models import Zipcode
>>> z = Zipcode(code=77096, poly='POLYGON(( 10 10, 10 20, 20 20, 20 15, 10 10))')
>>> z.save()
:class:`~django.contrib.gis.geos.GEOSGeometry` objects may also be used to save geometric models::
:class:`~django.contrib.gis.geos.GEOSGeometry` objects may also be used to save geometric models:
.. code-block:: pycon
>>> from django.contrib.gis.geos import GEOSGeometry
>>> poly = GEOSGeometry('POLYGON(( 10 10, 10 20, 20 20, 20 15, 10 10))')
@ -53,7 +57,9 @@ model)::
Moreover, if the ``GEOSGeometry`` is in a different coordinate system (has a
different SRID value) than that of the field, then it will be implicitly
transformed into the SRID of the model's field, using the spatial database's
transform procedure::
transform procedure:
.. code-block:: pycon
>>> poly_3084 = GEOSGeometry('POLYGON(( 10 10, 10 20, 20 20, 20 15, 10 10))', srid=3084) # SRID 3084 is 'NAD83(HARN) / Texas Centric Lambert Conformal'
>>> z = Zipcode(code=78212, poly=poly_3084)
@ -82,14 +88,18 @@ The raster field will therefore accept any input that is accepted by the
:class:`~django.contrib.gis.gdal.GDALRaster` constructor.
Here is an example of how to create a raster object from a raster file
``volcano.tif`` (assuming the ``Elevation`` model)::
``volcano.tif`` (assuming the ``Elevation`` model):
.. code-block:: pycon
>>> from elevation.models import Elevation
>>> dem = Elevation(name='Volcano', rast='/path/to/raster/volcano.tif')
>>> dem.save()
:class:`~django.contrib.gis.gdal.GDALRaster` objects may also be used to save
raster models::
raster models:
.. code-block:: pycon
>>> from django.contrib.gis.gdal import GDALRaster
>>> rast = GDALRaster({'width': 10, 'height': 10, 'name': 'Canyon', 'srid': 4326,
@ -97,7 +107,9 @@ raster models::
>>> dem = Elevation(name='Canyon', rast=rast)
>>> dem.save()
Note that this equivalent to::
Note that this equivalent to:
.. code-block:: pycon
>>> dem = Elevation.objects.create(
... name='Canyon',
@ -125,12 +137,16 @@ Geometry Lookups
----------------
Geographic queries with geometries take the following general form (assuming
the ``Zipcode`` model used in the :doc:`model-api`)::
the ``Zipcode`` model used in the :doc:`model-api`):
.. code-block:: pycon
>>> qs = Zipcode.objects.filter(<field>__<lookup_type>=<parameter>)
>>> qs = Zipcode.objects.exclude(...)
For example::
For example:
.. code-block:: pycon
>>> qs = Zipcode.objects.filter(poly__contains=pnt)
>>> qs = Elevation.objects.filter(poly__contains=rst)
@ -157,13 +173,17 @@ used to pass a band index. On the right hand side, a tuple of the raster and
band index can be specified.
This results in the following general form for lookups involving rasters
(assuming the ``Elevation`` model used in the :doc:`model-api`)::
(assuming the ``Elevation`` model used in the :doc:`model-api`):
.. code-block:: pycon
>>> qs = Elevation.objects.filter(<field>__<lookup_type>=<parameter>)
>>> qs = Elevation.objects.filter(<field>__<band_index>__<lookup_type>=<parameter>)
>>> qs = Elevation.objects.filter(<field>__<lookup_type>=(<raster_input, <band_index>)
For example::
For example:
.. code-block:: pycon
>>> qs = Elevation.objects.filter(rast__contains=geom)
>>> qs = Elevation.objects.filter(rast__contains=rst)
@ -256,7 +276,9 @@ For example, let's say we have a ``SouthTexasCity`` model (from the
# is used, units are in meters.
point = models.PointField(srid=32140)
Then distance queries may be performed as follows::
Then distance queries may be performed as follows:
.. code-block:: pycon
>>> from django.contrib.gis.geos import GEOSGeometry
>>> from django.contrib.gis.measure import D # ``D`` is a shortcut for ``Distance``
@ -273,7 +295,9 @@ Then distance queries may be performed as follows::
Raster queries work the same way by replacing the geometry field ``point`` with
a raster field, or the ``pnt`` object with a raster object, or both. To specify
the band index of a raster input on the right hand side, a 3-tuple can be
passed to the lookup as follows::
passed to the lookup as follows:
.. code-block:: pycon
>>> qs = SouthTexasCity.objects.filter(point__distance_gte=(rst, 2, D(km=7)))

View File

@ -8,7 +8,9 @@ Geographic Database Functions
The functions documented on this page allow users to access geographic database
functions to be used in annotations, aggregations, or filters in Django.
Example::
Example:
.. code-block:: pycon
>>> from django.contrib.gis.db.models.functions import Length
>>> Track.objects.annotate(length=Length('line')).filter(length__gt=100)
@ -61,7 +63,9 @@ Accepts a single geographic field or expression and returns a `GeoJSON
is not a complete GeoJSON structure but only the ``geometry`` key content of a
GeoJSON structure. See also :doc:`/ref/contrib/gis/serializers`.
Example::
Example:
.. code-block:: pycon
>>> City.objects.annotate(json=AsGeoJSON('point')).get(name='Chicago').json
{"type":"Point","coordinates":[-87.65018,41.85039]}
@ -94,7 +98,9 @@ SpatiaLite
Accepts a single geographic field or expression and returns a `Geographic Markup
Language (GML)`__ representation of the geometry.
Example::
Example:
.. code-block:: pycon
>>> qs = Zipcode.objects.annotate(gml=AsGML('poly'))
>>> print(qs[0].gml)
@ -123,7 +129,9 @@ __ https://en.wikipedia.org/wiki/Geography_Markup_Language
Accepts a single geographic field or expression and returns a `Keyhole Markup
Language (KML)`__ representation of the geometry.
Example::
Example:
.. code-block:: pycon
>>> qs = Zipcode.objects.annotate(kml=AsKML('poly'))
>>> print(qs[0].kml)
@ -176,7 +184,9 @@ Oracle, `PostGIS <https://postgis.net/docs/ST_AsBinary.html>`__, SpatiaLite
Accepts a single geographic field or expression and returns a `Well-known
binary (WKB)`_ representation of the geometry.
Example::
Example:
.. code-block:: pycon
>>> bytes(City.objects.annotate(wkb=AsWKB('point')).get(name='Chelyabinsk').wkb)
b'\x01\x01\x00\x00\x00]3\xf9f\x9b\x91K@\x00X\x1d9\xd2\xb9N@'
@ -193,7 +203,9 @@ Oracle, `PostGIS <https://postgis.net/docs/ST_AsText.html>`__, SpatiaLite
Accepts a single geographic field or expression and returns a `Well-known text
(WKT)`_ representation of the geometry.
Example::
Example:
.. code-block:: pycon
>>> City.objects.annotate(wkt=AsWKT('point')).get(name='Chelyabinsk').wkt
'POINT (55.137555 61.451728)'
@ -289,7 +301,9 @@ resource-intensive).
In the following example, the distance from the city of Hobart to every other
:class:`~django.contrib.gis.db.models.PointField` in the ``AustraliaCity``
queryset is calculated::
queryset is calculated:
.. code-block:: pycon
>>> from django.contrib.gis.db.models.functions import Distance
>>> pnt = AustraliaCity.objects.get(name='Hobart').point

View File

@ -36,7 +36,9 @@ The GDAL/OGR tools described here are designed to help you read in
your geospatial data, in order for most of them to be useful you have
to have some data to work with. If you're starting out and don't yet
have any data of your own to use, GeoDjango tests contain a number of
data sets that you can use for testing. You can download them here::
data sets that you can use for testing. You can download them here:
.. code-block:: shell
$ wget https://raw.githubusercontent.com/django/django/main/tests/gis_tests/data/cities/cities.{shp,prj,shx,dbf}
$ wget https://raw.githubusercontent.com/django/django/main/tests/gis_tests/data/rasters/raster.tif
@ -75,7 +77,9 @@ each feature in that layer.
Once you've created your ``DataSource``, you can find out how many layers
of data it contains by accessing the :attr:`layer_count` property, or
(equivalently) by using the ``len()`` function. For information on
accessing the layers of data themselves, see the next section::
accessing the layers of data themselves, see the next section:
.. code-block:: pycon
>>> from django.contrib.gis.gdal import DataSource
>>> ds = DataSource('/path/to/your/cities.shp')
@ -110,7 +114,9 @@ __ https://gdal.org/drivers/vector/
Typically, all the features in a given layer have the same geometry type.
The :attr:`geom_type` property of a layer is an :class:`OGRGeomType` that
identifies the feature type. We can use it to print out some basic
information about each layer in a :class:`DataSource`::
information about each layer in a :class:`DataSource`:
.. code-block:: pycon
>>> for layer in ds:
... print('Layer "%s": %i %ss' % (layer.name, len(layer), layer.geom_type.name))
@ -120,7 +126,9 @@ __ https://gdal.org/drivers/vector/
The example output is from the cities data source, loaded above, which
evidently contains one layer, called ``"cities"``, which contains three
point features. For simplicity, the examples below assume that you've
stored that layer in the variable ``layer``::
stored that layer in the variable ``layer``:
.. code-block:: pycon
>>> layer = ds[0]
@ -128,19 +136,25 @@ __ https://gdal.org/drivers/vector/
Returns the name of this layer in the data source.
.. code-block:: pycon
>>> layer.name
'cities'
.. attribute:: num_feat
Returns the number of features in the layer. Same as ``len(layer)``::
Returns the number of features in the layer. Same as ``len(layer)``:
.. code-block:: pycon
>>> layer.num_feat
3
.. attribute:: geom_type
Returns the geometry type of the layer, as an :class:`OGRGeomType` object::
Returns the geometry type of the layer, as an :class:`OGRGeomType` object:
.. code-block:: pycon
>>> layer.geom_type.name
'Point'
@ -148,14 +162,18 @@ __ https://gdal.org/drivers/vector/
.. attribute:: num_fields
Returns the number of fields in the layer, i.e the number of fields of
data associated with each feature in the layer::
data associated with each feature in the layer:
.. code-block:: pycon
>>> layer.num_fields
4
.. attribute:: fields
Returns a list of the names of each of the fields in this layer::
Returns a list of the names of each of the fields in this layer:
.. code-block:: pycon
>>> layer.fields
['Name', 'Population', 'Density', 'Created']
@ -163,7 +181,9 @@ __ https://gdal.org/drivers/vector/
.. attribute field_types
Returns a list of the data types of each of the fields in this layer. These
are subclasses of ``Field``, discussed below::
are subclasses of ``Field``, discussed below:
.. code-block:: pycon
>>> [ft.__name__ for ft in layer.field_types]
['OFTString', 'OFTReal', 'OFTReal', 'OFTDate']
@ -171,7 +191,9 @@ __ https://gdal.org/drivers/vector/
.. attribute:: field_widths
Returns a list of the maximum field widths for each of the fields in this
layer::
layer:
.. code-block:: pycon
>>> layer.field_widths
[80, 11, 24, 10]
@ -179,14 +201,18 @@ __ https://gdal.org/drivers/vector/
.. attribute:: field_precisions
Returns a list of the numeric precisions for each of the fields in this
layer. This is meaningless (and set to zero) for non-numeric fields::
layer. This is meaningless (and set to zero) for non-numeric fields:
.. code-block:: pycon
>>> layer.field_precisions
[0, 0, 15, 0]
.. attribute:: extent
Returns the spatial extent of this layer, as an :class:`Envelope` object::
Returns the spatial extent of this layer, as an :class:`Envelope` object:
.. code-block:: pycon
>>> layer.extent.tuple
(-104.609252, 29.763374, -95.23506, 38.971823)
@ -194,7 +220,9 @@ __ https://gdal.org/drivers/vector/
.. attribute:: srs
Property that returns the :class:`SpatialReference` associated with this
layer::
layer:
.. code-block:: pycon
>>> print(layer.srs)
GEOGCS["GCS_WGS_1984",
@ -212,7 +240,9 @@ __ https://gdal.org/drivers/vector/
layer. A spatial filter can only be set with an :class:`OGRGeometry`
instance, a 4-tuple extent, or ``None``. When set with something other than
``None``, only features that intersect the filter will be returned when
iterating over the layer::
iterating over the layer:
.. code-block:: pycon
>>> print(layer.spatial_filter)
None
@ -233,7 +263,9 @@ __ https://gdal.org/drivers/vector/
.. method:: get_fields()
A method that returns a list of the values of a given field for each
feature in the layer::
feature in the layer:
.. code-block:: pycon
>>> layer.get_fields('Name')
['Pueblo', 'Lawrence', 'Houston']
@ -243,7 +275,9 @@ __ https://gdal.org/drivers/vector/
A method that returns a list containing the geometry of each feature in the
layer. If the optional argument ``geos`` is set to ``True`` then the
geometries are converted to :class:`~django.contrib.gis.geos.GEOSGeometry`
objects. Otherwise, they are returned as :class:`OGRGeometry` objects::
objects. Otherwise, they are returned as :class:`OGRGeometry` objects:
.. code-block:: pycon
>>> [pt.tuple for pt in layer.get_geoms()]
[(-104.609252, 38.255001), (-95.23506, 38.971823), (-95.363151, 29.763374)]
@ -273,7 +307,9 @@ __ https://gdal.org/drivers/vector/
.. attribute:: geom
Returns the geometry for this feature, as an ``OGRGeometry`` object::
Returns the geometry for this feature, as an ``OGRGeometry`` object:
.. code-block:: pycon
>>> city.geom.tuple
(-104.609252, 38.255001)
@ -281,7 +317,9 @@ __ https://gdal.org/drivers/vector/
.. attribute:: get
A method that returns the value of the given field (specified by name)
for this feature, **not** a ``Field`` wrapper object::
for this feature, **not** a ``Field`` wrapper object:
.. code-block:: pycon
>>> city.get('Population')
102121
@ -309,7 +347,9 @@ __ https://gdal.org/drivers/vector/
.. attribute:: fid
Returns the feature identifier within the layer::
Returns the feature identifier within the layer:
.. code-block:: pycon
>>> city.fid
0
@ -317,7 +357,9 @@ __ https://gdal.org/drivers/vector/
.. attribute:: layer_name
Returns the name of the :class:`Layer` that the feature came from. This
will be the same for all features in a given layer::
will be the same for all features in a given layer:
.. code-block:: pycon
>>> city.layer_name
'cities'
@ -325,7 +367,9 @@ __ https://gdal.org/drivers/vector/
.. attribute:: index
A method that returns the index of the given field name. This will be the
same for all features in a given layer::
same for all features in a given layer:
.. code-block:: pycon
>>> city.index('Population')
1
@ -337,7 +381,9 @@ __ https://gdal.org/drivers/vector/
.. attribute:: name
Returns the name of this field::
Returns the name of this field:
.. code-block:: pycon
>>> city['Name'].name
'Name'
@ -345,14 +391,18 @@ __ https://gdal.org/drivers/vector/
.. attribute:: type
Returns the OGR type of this field, as an integer. The ``FIELD_CLASSES``
dictionary maps these values onto subclasses of ``Field``::
dictionary maps these values onto subclasses of ``Field``:
.. code-block:: pycon
>>> city['Density'].type
2
.. attribute:: type_name
Returns a string with the name of the data type of this field::
Returns a string with the name of the data type of this field:
.. code-block:: pycon
>>> city['Name'].type_name
'String'
@ -361,14 +411,18 @@ __ https://gdal.org/drivers/vector/
Returns the value of this field. The ``Field`` class itself returns the
value as a string, but each subclass returns the value in the most
appropriate form::
appropriate form:
.. code-block:: pycon
>>> city['Population'].value
102121
.. attribute:: width
Returns the width of this field::
Returns the width of this field:
.. code-block:: pycon
>>> city['Name'].width
80
@ -376,35 +430,45 @@ __ https://gdal.org/drivers/vector/
.. attribute:: precision
Returns the numeric precision of this field. This is meaningless (and set
to zero) for non-numeric fields::
to zero) for non-numeric fields:
.. code-block:: pycon
>>> city['Density'].precision
15
.. method:: as_double()
Returns the value of the field as a double (float)::
Returns the value of the field as a double (float):
.. code-block:: pycon
>>> city['Density'].as_double()
874.7
.. method:: as_int()
Returns the value of the field as an integer::
Returns the value of the field as an integer:
.. code-block:: pycon
>>> city['Population'].as_int()
102121
.. method:: as_string()
Returns the value of the field as a string::
Returns the value of the field as a string:
.. code-block:: pycon
>>> city['Name'].as_string()
'Pueblo'
.. method:: as_datetime()
Returns the value of the field as a tuple of date and time components::
Returns the value of the field as a tuple of date and time components:
.. code-block:: pycon
>>> city['Created'].as_datetime()
(c_long(1999), c_long(5), c_long(23), c_long(0), c_long(0), c_long(0), c_long(0))
@ -432,7 +496,9 @@ OGR Geometries
around OGR's internal geometry representation. Thus, they allow for more
efficient access to data when using :class:`DataSource`. Unlike its GEOS
counterpart, :class:`OGRGeometry` supports spatial reference systems and
coordinate transformation::
coordinate transformation:
.. code-block:: pycon
>>> from django.contrib.gis.gdal import OGRGeometry
>>> polygon = OGRGeometry('POLYGON((0 0, 5 0, 5 5, 0 5))')
@ -478,7 +544,9 @@ coordinate transformation::
.. attribute:: dimension
Returns the number of coordinated dimensions of the geometry, i.e. 0
for points, 1 for lines, and so forth::
for points, 1 for lines, and so forth:
.. code-block:: pycon
>> polygon.dimension
2
@ -490,14 +558,18 @@ coordinate transformation::
.. attribute:: geom_count
Returns the number of elements in this geometry::
Returns the number of elements in this geometry:
.. code-block:: pycon
>>> polygon.geom_count
1
.. attribute:: point_count
Returns the number of points used to describe this geometry::
Returns the number of points used to describe this geometry:
.. code-block:: pycon
>>> polygon.point_count
4
@ -516,7 +588,9 @@ coordinate transformation::
.. attribute:: geom_name
Returns the name of the type of this geometry::
Returns the name of the type of this geometry:
.. code-block:: pycon
>>> polygon.geom_name
'POLYGON'
@ -524,7 +598,9 @@ coordinate transformation::
.. attribute:: area
Returns the area of this geometry, or 0 for geometries that do not contain
an area::
an area:
.. code-block:: pycon
>>> polygon.area
25.0
@ -536,7 +612,9 @@ coordinate transformation::
.. attribute:: extent
Returns the envelope of this geometry as a 4-tuple, instead of as an
:class:`Envelope` object::
:class:`Envelope` object:
.. code-block:: pycon
>>> point.extent
(0.0, 0.0, 5.0, 5.0)
@ -547,7 +625,9 @@ coordinate transformation::
``None`` if no spatial reference system has been assigned to it.
If assigned, accessing this property returns a :class:`SpatialReference`
object. It may be set with another :class:`SpatialReference` object,
or any input that :class:`SpatialReference` accepts. Example::
or any input that :class:`SpatialReference` accepts. Example:
.. code-block:: pycon
>>> city.geom.srs.name
'GCS_WGS_1984'
@ -566,21 +646,27 @@ coordinate transformation::
.. attribute:: gml
Returns a string representation of this geometry in GML format::
Returns a string representation of this geometry in GML format:
.. code-block:: pycon
>>> OGRGeometry('POINT(1 2)').gml
'<gml:Point><gml:coordinates>1,2</gml:coordinates></gml:Point>'
.. attribute:: hex
Returns a string representation of this geometry in HEX WKB format::
Returns a string representation of this geometry in HEX WKB format:
.. code-block:: pycon
>>> OGRGeometry('POINT(1 2)').hex
'0101000000000000000000F03F0000000000000040'
.. attribute:: json
Returns a string representation of this geometry in JSON format::
Returns a string representation of this geometry in JSON format:
.. code-block:: pycon
>>> OGRGeometry('POINT(1 2)').json
'{ "type": "Point", "coordinates": [ 1.000000, 2.000000 ] }'
@ -592,7 +678,9 @@ coordinate transformation::
.. attribute:: wkb_size
Returns the size of the WKB buffer needed to hold a WKB representation
of this geometry::
of this geometry:
.. code-block:: pycon
>>> OGRGeometry('POINT(1 2)').wkb_size
21
@ -616,7 +704,9 @@ coordinate transformation::
.. method:: close_rings()
If there are any rings within this geometry that have not been closed,
this routine will do so by adding the starting point to the end::
this routine will do so by adding the starting point to the end:
.. code-block:: pycon
>>> triangle = OGRGeometry('LINEARRING (0 0,0 1,1 0)')
>>> triangle.close_rings()
@ -706,7 +796,9 @@ coordinate transformation::
.. attribute:: tuple
Returns the coordinates of a point geometry as a tuple, the
coordinates of a line geometry as a tuple of tuples, and so forth::
coordinates of a line geometry as a tuple of tuples, and so forth:
.. code-block:: pycon
>>> OGRGeometry('POINT (1 2)').tuple
(1.0, 2.0)
@ -721,14 +813,18 @@ coordinate transformation::
.. attribute:: x
Returns the X coordinate of this point::
Returns the X coordinate of this point:
.. code-block:: pycon
>>> OGRGeometry('POINT (1 2)').x
1.0
.. attribute:: y
Returns the Y coordinate of this point::
Returns the Y coordinate of this point:
.. code-block:: pycon
>>> OGRGeometry('POINT (1 2)').y
2.0
@ -736,7 +832,9 @@ coordinate transformation::
.. attribute:: z
Returns the Z coordinate of this point, or ``None`` if the point does not
have a Z coordinate::
have a Z coordinate:
.. code-block:: pycon
>>> OGRGeometry('POINT (1 2 3)').z
3.0
@ -745,14 +843,18 @@ coordinate transformation::
.. attribute:: x
Returns a list of X coordinates in this line::
Returns a list of X coordinates in this line:
.. code-block:: pycon
>>> OGRGeometry('LINESTRING (1 2,3 4)').x
[1.0, 3.0]
.. attribute:: y
Returns a list of Y coordinates in this line::
Returns a list of Y coordinates in this line:
.. code-block:: pycon
>>> OGRGeometry('LINESTRING (1 2,3 4)').y
[2.0, 4.0]
@ -760,7 +862,9 @@ coordinate transformation::
.. attribute:: z
Returns a list of Z coordinates in this line, or ``None`` if the line does
not have Z coordinates::
not have Z coordinates:
.. code-block:: pycon
>>> OGRGeometry('LINESTRING (1 2 3,4 5 6)').z
[3.0, 6.0]
@ -794,7 +898,9 @@ coordinate transformation::
.. class:: OGRGeomType(type_input)
This class allows for the representation of an OGR geometry type
in any of several ways::
in any of several ways:
.. code-block:: pycon
>>> from django.contrib.gis.gdal import OGRGeomType
>>> gt1 = OGRGeomType(3) # Using an integer for the type
@ -805,14 +911,18 @@ coordinate transformation::
.. attribute:: name
Returns a short-hand string form of the OGR Geometry type::
Returns a short-hand string form of the OGR Geometry type:
.. code-block:: pycon
>>> gt1.name
'Polygon'
.. attribute:: num
Returns the number corresponding to the OGR geometry type::
Returns the number corresponding to the OGR geometry type:
.. code-block:: pycon
>>> gt1.num
3
@ -820,7 +930,9 @@ coordinate transformation::
.. attribute:: django
Returns the Django field type (a subclass of GeometryField) to use for
storing this OGR type, or ``None`` if there is no appropriate Django type::
storing this OGR type, or ``None`` if there is no appropriate Django type:
.. code-block:: pycon
>>> gt1.django
'PolygonField'
@ -885,7 +997,9 @@ Coordinate System Objects
* A shorthand string for well-known standards (``'WGS84'``, ``'WGS72'``,
``'NAD27'``, ``'NAD83'``)
Example::
Example:
.. code-block:: pycon
>>> wgs84 = SpatialReference('WGS84') # shorthand string
>>> wgs84 = SpatialReference(4326) # EPSG code
@ -907,7 +1021,9 @@ Coordinate System Objects
Returns the value of the given string attribute node, ``None`` if the node
doesn't exist. Can also take a tuple as a parameter, (target, child), where
child is the index of the attribute in the WKT. For example::
child is the index of the attribute in the WKT. For example:
.. code-block:: pycon
>>> wkt = 'GEOGCS["WGS 84", DATUM["WGS_1984, ... AUTHORITY["EPSG","4326"]]')
>>> srs = SpatialReference(wkt) # could also use 'WGS84', or 4326
@ -1068,7 +1184,9 @@ Coordinate System Objects
Represents a coordinate system transform. It is initialized with two
:class:`SpatialReference`, representing the source and target coordinate
systems, respectively. These objects should be used when performing the same
coordinate transformation repeatedly on different geometries::
coordinate transformation repeatedly on different geometries:
.. code-block:: pycon
>>> ct = CoordTransform(SpatialReference('WGS84'), SpatialReference('NAD83'))
>>> for feat in layer:
@ -1721,7 +1839,9 @@ Key Default Usage
The following example uses some of the options available for the
`GTiff driver`__. The result is a compressed signed byte raster with an
internal tiling scheme. The internal tiles have a block size of 23 by 23::
internal tiling scheme. The internal tiles have a block size of 23 by 23:
.. code-block:: pycon
>>> GDALRaster({
... 'driver': 'GTiff',
@ -1787,7 +1907,9 @@ from a remote storage or returned from a view without being written to disk.
``/vsimem/``.
Input provided as ``bytes`` has to be a full binary representation of a file.
For instance::
For instance:
.. code-block:: pycon
# Read a raster as a file object from a remote source.
>>> from urllib.request import urlopen
@ -1807,7 +1929,9 @@ dictionary representation and provide a ``name`` argument that starts with
of the raster.
Here's how to create a raster and return it as a file in an
:class:`~django.http.HttpResponse`::
:class:`~django.http.HttpResponse`:
.. code-block:: pycon
>>> from django.http import HttpResponse
>>> rst = GDALRaster({
@ -1838,7 +1962,9 @@ Compressed rasters
Instead decompressing the file and instantiating the resulting raster, GDAL can
directly access compressed files using the ``/vsizip/``, ``/vsigzip/``, or
``/vsitar/`` virtual filesystems::
``/vsitar/`` virtual filesystems:
.. code-block:: pycon
>>> from django.contrib.gis.gdal import GDALRaster
>>> rst = GDALRaster('/vsizip/path/to/your/file.zip/path/to/raster.tif')
@ -1852,7 +1978,9 @@ GDAL can support online resources and storage providers transparently. As long
as it's built with such capabilities.
To access a public raster file with no authentication, you can use
``/vsicurl/``::
``/vsicurl/``:
.. code-block:: pycon
>>> from django.contrib.gis.gdal import GDALRaster
>>> rst = GDALRaster('/vsicurl/https://example.com/raster.tif')

View File

@ -31,7 +31,9 @@ __ https://github.com/maxmind/libmaxminddb/
Example
=======
Here is an example of its usage::
Here is an example of its usage:
.. code-block:: pycon
>>> from django.contrib.gis.geoip2 import GeoIP2
>>> g = GeoIP2()

View File

@ -856,7 +856,9 @@ Keyword Argument Description
__ https://docs.oracle.com/en/database/oracle/oracle-database/21/spatl/
spatial-concepts.html#GUID-CE10AB14-D5EA-43BA-A647-DAC9EEF41EE6
Example::
Example:
.. code-block:: pycon
>>> from django.contrib.gis.db.models import Extent, Union
>>> WorldBorder.objects.aggregate(Extent('mpoly'), Union('mpoly'))
@ -886,7 +888,9 @@ Oracle, SpatiaLite
Returns the extent of all ``geo_field`` in the ``QuerySet`` as a four-tuple,
comprising the lower left coordinate and the upper right coordinate.
Example::
Example:
.. code-block:: pycon
>>> qs = City.objects.filter(name__in=('Houston', 'Dallas')).aggregate(Extent('poly'))
>>> print(qs['poly__extent'])
@ -903,7 +907,9 @@ Returns the 3D extent of all ``geo_field`` in the ``QuerySet`` as a six-tuple,
comprising the lower left coordinate and upper right coordinate (each with x, y,
and z coordinates).
Example::
Example:
.. code-block:: pycon
>>> qs = City.objects.filter(name__in=('Houston', 'Dallas')).aggregate(Extent3D('poly'))
>>> print(qs['poly__extent3d'])
@ -920,7 +926,9 @@ SpatiaLite
Returns a ``LineString`` constructed from the point field geometries in the
``QuerySet``. Currently, ordering the queryset has no effect.
Example::
Example:
.. code-block:: pycon
>>> qs = City.objects.filter(name__in=('Houston', 'Dallas')).aggregate(MakeLine('poly'))
>>> print(qs['poly__makeline'])
@ -944,7 +952,9 @@ large querysets.
If the computation time for using this method is too expensive, consider
using :class:`Collect` instead.
Example::
Example:
.. code-block:: pycon
>>> u = Zipcode.objects.aggregate(Union(poly)) # This may take a long time.
>>> u = Zipcode.objects.filter(poly__within=bbox).aggregate(Union(poly)) # A more sensible approach.

View File

@ -50,7 +50,9 @@ Creating a Geometry
:class:`GEOSGeometry` objects may be created in a few ways. The first is
to simply instantiate the object on some spatial input -- the following
are examples of creating the same geometry from WKT, HEX, WKB, and GeoJSON::
are examples of creating the same geometry from WKT, HEX, WKB, and GeoJSON:
.. code-block:: pycon
>>> from django.contrib.gis.geos import GEOSGeometry
>>> pnt = GEOSGeometry('POINT(5 23)') # WKT
@ -60,12 +62,16 @@ are examples of creating the same geometry from WKT, HEX, WKB, and GeoJSON::
Another option is to use the constructor for the specific geometry type
that you wish to create. For example, a :class:`Point` object may be
created by passing in the X and Y coordinates into its constructor::
created by passing in the X and Y coordinates into its constructor:
.. code-block:: pycon
>>> from django.contrib.gis.geos import Point
>>> pnt = Point(5, 23)
All these constructors take the keyword argument ``srid``. For example::
All these constructors take the keyword argument ``srid``. For example:
.. code-block:: pycon
>>> from django.contrib.gis.geos import GEOSGeometry, LineString, Point
>>> print(GEOSGeometry('POINT (0 0)', srid=4326))
@ -76,7 +82,9 @@ All these constructors take the keyword argument ``srid``. For example::
SRID=32140;POINT (0 0)
Finally, there is the :func:`fromfile` factory method which returns a
:class:`GEOSGeometry` object from a file::
:class:`GEOSGeometry` object from a file:
.. code-block:: pycon
>>> from django.contrib.gis.geos import fromfile
>>> pnt = fromfile('/path/to/pnt.wkt')
@ -97,14 +105,18 @@ Geometries are Pythonic
-----------------------
:class:`GEOSGeometry` objects are 'Pythonic', in other words components may
be accessed, modified, and iterated over using standard Python conventions.
For example, you can iterate over the coordinates in a :class:`Point`::
For example, you can iterate over the coordinates in a :class:`Point`:
.. code-block:: pycon
>>> pnt = Point(5, 23)
>>> [coord for coord in pnt]
[5.0, 23.0]
With any geometry object, the :attr:`GEOSGeometry.coords` property
may be used to get the geometry coordinates as a Python tuple::
may be used to get the geometry coordinates as a Python tuple:
.. code-block:: pycon
>>> pnt.coords
(5.0, 23.0)
@ -112,7 +124,9 @@ may be used to get the geometry coordinates as a Python tuple::
You can get/set geometry components using standard Python indexing
techniques. However, what is returned depends on the geometry type
of the object. For example, indexing on a :class:`LineString`
returns a coordinate tuple::
returns a coordinate tuple:
.. code-block:: pycon
>>> from django.contrib.gis.geos import LineString
>>> line = LineString((0, 0), (0, 50), (50, 50), (50, 0), (0, 0))
@ -122,7 +136,9 @@ returns a coordinate tuple::
(50.0, 0.0)
Whereas indexing on a :class:`Polygon` will return the ring
(a :class:`LinearRing` object) corresponding to the index::
(a :class:`LinearRing` object) corresponding to the index:
.. code-block:: pycon
>>> from django.contrib.gis.geos import Polygon
>>> poly = Polygon( ((0.0, 0.0), (0.0, 50.0), (50.0, 50.0), (50.0, 0.0), (0.0, 0.0)) )
@ -132,7 +148,9 @@ Whereas indexing on a :class:`Polygon` will return the ring
(50.0, 0.0)
In addition, coordinates/components of the geometry may added or modified,
just like a Python list::
just like a Python list:
.. code-block:: pycon
>>> line[0] = (1.0, 1.0)
>>> line.pop()
@ -141,7 +159,9 @@ just like a Python list::
>>> line.coords
((1.0, 1.0), (0.0, 50.0), (50.0, 50.0), (50.0, 0.0), (1.0, 1.0))
Geometries support set-like operators::
Geometries support set-like operators:
.. code-block:: pycon
>>> from django.contrib.gis.geos import LineString
>>> ls1 = LineString((0, 0), (2, 2))
@ -160,7 +180,9 @@ Geometries support set-like operators::
The :class:`~GEOSGeometry` equality operator uses
:meth:`~GEOSGeometry.equals_exact`, not :meth:`~GEOSGeometry.equals`, i.e.
it requires the compared geometries to have the same coordinates in the
same positions with the same SRIDs::
same positions with the same SRIDs:
.. code-block:: pycon
>>> from django.contrib.gis.geos import LineString
>>> ls1 = LineString((0, 0), (1, 1))
@ -191,7 +213,9 @@ given ``geo_input`` argument, and then assumes the proper geometry subclass
The ``srid`` parameter, if given, is set as the SRID of the created geometry if
``geo_input`` doesn't have an SRID. If different SRIDs are provided through the
``geo_input`` and ``srid`` parameters, ``ValueError`` is raised::
``geo_input`` and ``srid`` parameters, ``ValueError`` is raised:
.. code-block:: pycon
>>> from django.contrib.gis.geos import GEOSGeometry
>>> GEOSGeometry('POINT EMPTY', srid=4326).ewkt
@ -246,7 +270,9 @@ Properties
.. attribute:: GEOSGeometry.geom_type
Returns a string corresponding to the type of geometry. For example::
Returns a string corresponding to the type of geometry. For example:
.. code-block:: pycon
>>> pnt = GEOSGeometry('POINT(5 23)')
>>> pnt.geom_type
@ -307,7 +333,9 @@ Properties
.. attribute:: GEOSGeometry.srid
Property that may be used to retrieve or set the SRID associated with the
geometry. For example::
geometry. For example:
.. code-block:: pycon
>>> pnt = Point(5, 23)
>>> print(pnt.srid)
@ -669,7 +697,9 @@ Other Properties & Methods
Converts this geometry to canonical form. If the ``clone`` keyword is set,
then the geometry is not modified and a normalized clone of the geometry is
returned instead::
returned instead:
.. code-block:: pycon
>>> g = MultiPoint(Point(0, 0), Point(2, 2), Point(1, 1))
>>> print(g)
@ -685,13 +715,17 @@ Other Properties & Methods
``Point`` objects are instantiated using arguments that represent the
component coordinates of the point or with a single sequence coordinates.
For example, the following are equivalent::
For example, the following are equivalent:
.. code-block:: pycon
>>> pnt = Point(5, 23)
>>> pnt = Point([5, 23])
Empty ``Point`` objects may be instantiated by passing no arguments or an
empty sequence. The following are equivalent::
empty sequence. The following are equivalent:
.. code-block:: pycon
>>> pnt = Point()
>>> pnt = Point([])
@ -703,19 +737,25 @@ Other Properties & Methods
``LineString`` objects are instantiated using arguments that are either a
sequence of coordinates or :class:`Point` objects. For example, the
following are equivalent::
following are equivalent:
.. code-block:: pycon
>>> ls = LineString((0, 0), (1, 1))
>>> ls = LineString(Point(0, 0), Point(1, 1))
In addition, ``LineString`` objects may also be created by passing in a
single sequence of coordinate or :class:`Point` objects::
single sequence of coordinate or :class:`Point` objects:
.. code-block:: pycon
>>> ls = LineString( ((0, 0), (1, 1)) )
>>> ls = LineString( [Point(0, 0), Point(1, 1)] )
Empty ``LineString`` objects may be instantiated by passing no arguments
or an empty sequence. The following are equivalent::
or an empty sequence. The following are equivalent:
.. code-block:: pycon
>>> ls = LineString()
>>> ls = LineString([])
@ -732,7 +772,9 @@ Other Properties & Methods
``LinearRing`` objects are constructed in the exact same way as
:class:`LineString` objects, however the coordinates must be *closed*, in
other words, the first coordinates must be the same as the last
coordinates. For example::
coordinates. For example:
.. code-block:: pycon
>>> ls = LinearRing((0, 0), (0, 1), (1, 1), (0, 0))
@ -751,7 +793,9 @@ Other Properties & Methods
``Polygon`` objects may be instantiated by passing in parameters that
represent the rings of the polygon. The parameters must either be
:class:`LinearRing` instances, or a sequence that may be used to construct a
:class:`LinearRing`::
:class:`LinearRing`:
.. code-block:: pycon
>>> ext_coords = ((0, 0), (0, 1), (1, 1), (1, 0), (0, 0))
>>> int_coords = ((0.4, 0.4), (0.4, 0.6), (0.6, 0.6), (0.6, 0.4), (0.4, 0.4))
@ -773,7 +817,9 @@ Other Properties & Methods
or ``>``, but as the comparison is made through Polygon's
:class:`LineString`, it does not mean much (but is consistent and quick).
You can always force the comparison with the :attr:`~GEOSGeometry.area`
property::
property:
.. code-block:: pycon
>>> if poly_1.area > poly_2.area:
>>> pass
@ -789,7 +835,9 @@ Geometry Collections
.. class:: MultiPoint(*args, **kwargs)
``MultiPoint`` objects may be instantiated by passing in :class:`Point`
objects as arguments, or a single sequence of :class:`Point` objects::
objects as arguments, or a single sequence of :class:`Point` objects:
.. code-block:: pycon
>>> mp = MultiPoint(Point(0, 0), Point(1, 1))
>>> mp = MultiPoint( (Point(0, 0), Point(1, 1)) )
@ -801,7 +849,9 @@ Geometry Collections
``MultiLineString`` objects may be instantiated by passing in
:class:`LineString` objects as arguments, or a single sequence of
:class:`LineString` objects::
:class:`LineString` objects:
.. code-block:: pycon
>>> ls1 = LineString((0, 0), (1, 1))
>>> ls2 = LineString((2, 2), (3, 3))
@ -823,7 +873,9 @@ Geometry Collections
.. class:: MultiPolygon(*args, **kwargs)
``MultiPolygon`` objects may be instantiated by passing :class:`Polygon`
objects as arguments, or a single sequence of :class:`Polygon` objects::
objects as arguments, or a single sequence of :class:`Polygon` objects:
.. code-block:: pycon
>>> p1 = Polygon( ((0, 0), (0, 1), (1, 1), (0, 0)) )
>>> p2 = Polygon( ((1, 1), (1, 2), (2, 2), (1, 1)) )
@ -837,7 +889,9 @@ Geometry Collections
``GeometryCollection`` objects may be instantiated by passing in other
:class:`GEOSGeometry` as arguments, or a single sequence of
:class:`GEOSGeometry` objects::
:class:`GEOSGeometry` objects:
.. code-block:: pycon
>>> poly = Polygon( ((0, 0), (0, 1), (1, 1), (0, 0)) )
>>> gc = GeometryCollection(Point(0, 0), MultiPoint(Point(0, 0), Point(1, 1)), poly)
@ -856,7 +910,9 @@ geometry can be orders of magnitude faster -- the more complex the geometry
that is prepared, the larger the speedup in the operation. For more information,
please consult the `GEOS wiki page on prepared geometries <https://trac.osgeo.org/geos/wiki/PreparedGeometry>`_.
For example::
For example:
.. code-block:: pycon
>>> from django.contrib.gis.geos import Point, Polygon
>>> poly = Polygon.from_bbox((0, 0, 5, 5))
@ -899,7 +955,9 @@ Geometry Factories
:type file_h: a Python ``file`` object or a string path to the file
:rtype: a :class:`GEOSGeometry` corresponding to the spatial data in the file
Example::
Example:
.. code-block:: pycon
>>> from django.contrib.gis.geos import fromfile
>>> g = fromfile('/home/bob/geom.wkt')
@ -915,7 +973,9 @@ Geometry Factories
``fromstr(string, srid)`` is equivalent to
:class:`GEOSGeometry(string, srid) <GEOSGeometry>`.
Example::
Example:
.. code-block:: pycon
>>> from django.contrib.gis.geos import fromstr
>>> pnt = fromstr('POINT(-90.5 29.5)', srid=4326)
@ -931,7 +991,9 @@ and/or WKT input given to their ``read(geom)`` method.
.. class:: WKBReader
Example::
Example:
.. code-block:: pycon
>>> from django.contrib.gis.geos import WKBReader
>>> wkb_r = WKBReader()
@ -940,7 +1002,9 @@ and/or WKT input given to their ``read(geom)`` method.
.. class:: WKTReader
Example::
Example:
.. code-block:: pycon
>>> from django.contrib.gis.geos import WKTReader
>>> wkt_r = WKTReader()
@ -967,7 +1031,9 @@ include the SRID value (in other words, EWKB).
.. method:: WKBWriter.write(geom)
Returns the WKB of the given geometry as a Python ``buffer`` object.
Example::
Example:
.. code-block:: pycon
>>> from django.contrib.gis.geos import Point, WKBWriter
>>> pnt = Point(1, 1)
@ -977,7 +1043,9 @@ include the SRID value (in other words, EWKB).
.. method:: WKBWriter.write_hex(geom)
Returns WKB of the geometry in hexadecimal. Example::
Returns WKB of the geometry in hexadecimal. Example:
.. code-block:: pycon
>>> from django.contrib.gis.geos import Point, WKBWriter
>>> pnt = Point(1, 1)
@ -997,7 +1065,9 @@ include the SRID value (in other words, EWKB).
1 Little Endian (e.g., compatible with x86 systems)
=============== =================================================
Example::
Example:
.. code-block:: pycon
>>> from django.contrib.gis.geos import Point, WKBWriter
>>> wkb_w = WKBWriter()
@ -1020,7 +1090,9 @@ include the SRID value (in other words, EWKB).
3 Output 3D WKB.
============ ===========================
Example::
Example:
.. code-block:: pycon
>>> from django.contrib.gis.geos import Point, WKBWriter
>>> wkb_w = WKBWriter()
@ -1036,7 +1108,9 @@ include the SRID value (in other words, EWKB).
.. attribute:: WKBWriter.srid
Set this property with a boolean to indicate whether the SRID of the
geometry should be included with the WKB representation. Example::
geometry should be included with the WKB representation. Example:
.. code-block:: pycon
>>> from django.contrib.gis.geos import Point, WKBWriter
>>> wkb_w = WKBWriter()
@ -1055,7 +1129,9 @@ include the SRID value (in other words, EWKB).
.. method:: WKTWriter.write(geom)
Returns the WKT of the given geometry. Example::
Returns the WKT of the given geometry. Example:
.. code-block:: pycon
>>> from django.contrib.gis.geos import Point, WKTWriter
>>> pnt = Point(1, 1)
@ -1072,6 +1148,8 @@ include the SRID value (in other words, EWKB).
This property is used to enable or disable trimming of
unnecessary decimals.
.. code-block:: pycon
>>> from django.contrib.gis.geos import Point, WKTWriter
>>> pnt = Point(1, 1)
>>> wkt_w = WKTWriter()

View File

@ -85,7 +85,9 @@ is required.
.. note::
On Linux platforms, it may be necessary to run the ``ldconfig`` command
after installing each library. For example::
after installing each library. For example:
.. code-block:: shell
$ sudo make install
$ sudo ldconfig
@ -106,19 +108,25 @@ internal geometry representation used by GeoDjango (it's behind the "lazy"
geometries). Specifically, the C API library is called (e.g., ``libgeos_c.so``)
directly from Python using ctypes.
First, download GEOS from the GEOS website and untar the source archive::
First, download GEOS from the GEOS website and untar the source archive:
.. code-block:: shell
$ wget https://download.osgeo.org/geos/geos-X.Y.Z.tar.bz2
$ tar xjf geos-X.Y.Z.tar.bz2
Then step into the GEOS directory, create a ``build`` folder, and step into
it::
it:
.. code-block:: shell
$ cd geos-X.Y.Z
$ mkdir build
$ cd build
Then build and install the package::
Then build and install the package:
.. code-block:: shell
$ cmake -DCMAKE_BUILD_TYPE=Release ..
$ cmake --build .
@ -149,7 +157,9 @@ If using a binary package of GEOS (e.g., on Ubuntu), you may need to :ref:`binut
If your GEOS library is in a non-standard location, or you don't want to
modify the system's library path then the :setting:`GEOS_LIBRARY_PATH`
setting may be added to your Django settings file with the full path to the
GEOS C library. For example::
GEOS C library. For example:
.. code-block:: shell
GEOS_LIBRARY_PATH = '/home/bob/local/lib/libgeos_c.so'
@ -168,18 +178,24 @@ PROJ
`PROJ`_ is a library for converting geospatial data to different coordinate
reference systems.
First, download the PROJ source code::
First, download the PROJ source code:
.. code-block:: shell
$ wget https://download.osgeo.org/proj/proj-X.Y.Z.tar.gz
... and datum shifting files (download ``proj-datumgrid-X.Y.tar.gz`` for
PROJ < 7.x) [#]_::
PROJ < 7.x) [#]_:
.. code-block:: shell
$ wget https://download.osgeo.org/proj/proj-data-X.Y.tar.gz
Next, untar the source code archive, and extract the datum shifting files in the
``data`` subdirectory (use ``nad`` subdirectory for PROJ < 6.x). This must be
done *prior* to configuration::
done *prior* to configuration:
.. code-block:: shell
$ tar xzf proj-X.Y.Z.tar.gz
$ cd proj-X.Y.Z/data
@ -190,13 +206,17 @@ For PROJ 9.x and greater, releases only support builds using ``CMake`` (see
`PROJ RFC-7`_).
To build with ``CMake`` ensure your system meets the `build requirements`_.
Then create a ``build`` folder in the PROJ directory, and step into it::
Then create a ``build`` folder in the PROJ directory, and step into it:
.. code-block:: shell
$ cd proj-X.Y.Z
$ mkdir build
$ cd build
Finally, configure, make and install PROJ::
Finally, configure, make and install PROJ:
.. code-block:: shell
$ cmake ..
$ cmake --build .
@ -215,20 +235,26 @@ reading most vector and raster spatial data formats. Currently, GeoDjango only
supports :doc:`GDAL's vector data <../gdal>` capabilities [#]_.
:ref:`geosbuild` and :ref:`proj4` should be installed prior to building GDAL.
First download the latest GDAL release version and untar the archive::
First download the latest GDAL release version and untar the archive:
.. code-block:: shell
$ wget https://download.osgeo.org/gdal/X.Y.Z/gdal-X.Y.Z.tar.gz
$ tar xzf gdal-X.Y.Z.tar.gz
For GDAL 3.6.x and greater, releases only support builds using ``CMake``. To
build with ``CMake`` create a ``build`` folder in the GDAL directory, and step
into it::
into it:
.. code-block:: shell
$ cd gdal-X.Y.Z
$ mkdir build
$ cd build
Finally, configure, make and install GDAL::
Finally, configure, make and install GDAL:
.. code-block:: shell
$ cmake ..
$ cmake --build .
@ -258,7 +284,9 @@ When GeoDjango can't find the GDAL library, configure your :ref:`libsettings`
If your GDAL library is in a non-standard location, or you don't want to
modify the system's library path then the :setting:`GDAL_LIBRARY_PATH`
setting may be added to your Django settings file with the full path to
the GDAL library. For example::
the GDAL library. For example:
.. code-block:: shell
GDAL_LIBRARY_PATH = '/home/sue/local/lib/libgdal.so'

View File

@ -2,8 +2,6 @@
GeoDjango Installation
======================
.. highlight:: console
Overview
========
In general, GeoDjango installation requires:
@ -141,7 +139,9 @@ A user may set this environment variable to customize the library paths
they want to use. The typical library directory for software
built from source is ``/usr/local/lib``. Thus, ``/usr/local/lib`` needs
to be included in the ``LD_LIBRARY_PATH`` variable. For example, the user
could place the following in their bash profile::
could place the following in their bash profile:
.. code-block:: shell
export LD_LIBRARY_PATH=/usr/local/lib
@ -151,7 +151,9 @@ Setting system library path
On GNU/Linux systems, there is typically a file in ``/etc/ld.so.conf``, which may include
additional paths from files in another directory, such as ``/etc/ld.so.conf.d``.
As the root user, add the custom library path (like ``/usr/local/lib``) on a
new line in ``ld.so.conf``. This is *one* example of how to do so::
new line in ``ld.so.conf``. This is *one* example of how to do so:
.. code-block:: shell
$ sudo echo /usr/local/lib >> /etc/ld.so.conf
$ sudo ldconfig
@ -159,7 +161,9 @@ new line in ``ld.so.conf``. This is *one* example of how to do so::
For OpenSolaris users, the system library path may be modified using the
``crle`` utility. Run ``crle`` with no options to see the current configuration
and use ``crle -l`` to set with the new library path. Be *very* careful when
modifying the system library path::
modifying the system library path:
.. code-block:: shell
# crle -l $OLD_PATH:/usr/local/lib
@ -176,11 +180,15 @@ Linux system then Python's ctypes may not be able to find your library even if
your library path is set correctly and geospatial libraries were built perfectly.
The ``binutils`` package may be installed on Debian and Ubuntu systems using the
following command::
following command:
.. code-block:: shell
$ sudo apt-get install binutils
Similarly, on Red Hat and CentOS systems::
Similarly, on Red Hat and CentOS systems:
.. code-block:: shell
$ sudo yum install binutils
@ -221,7 +229,9 @@ __ https://www.python.org/ftp/python/
You will need to modify the ``PATH`` environment variable in your
``.profile`` file so that the new version of Python is used when
``python`` is entered at the command-line::
``python`` is entered at the command-line:
.. code-block:: shell
export PATH=/Library/Frameworks/Python.framework/Versions/Current/bin:$PATH
@ -255,7 +265,9 @@ It provides recipes for the GeoDjango prerequisites on Macintosh computers
running macOS. Because Homebrew still builds the software from source, `Xcode`_
is required.
Summary::
Summary:
.. code-block:: shell
$ brew install postgresql
$ brew install postgis
@ -287,7 +299,9 @@ MacPorts
running macOS. Because MacPorts still builds the software from source,
`Xcode`_ is required.
Summary::
Summary:
.. code-block:: shell
$ sudo port install postgresql13-server
$ sudo port install geos
@ -299,12 +313,16 @@ Summary::
.. note::
You will also have to modify the ``PATH`` in your ``.profile`` so
that the MacPorts programs are accessible from the command-line::
that the MacPorts programs are accessible from the command-line:
.. code-block:: shell
export PATH=/opt/local/bin:/opt/local/lib/postgresql13/bin
In addition, add the ``DYLD_FALLBACK_LIBRARY_PATH`` setting so that
the libraries can be found by Python::
the libraries can be found by Python:
.. code-block:: shell
export DYLD_FALLBACK_LIBRARY_PATH=/opt/local/lib:/opt/local/lib/postgresql13
@ -434,7 +452,9 @@ psycopg
The ``psycopg`` Python module provides the interface between Python and the
PostgreSQL database. ``psycopg`` can be installed via pip within your Python
virtual environment::
virtual environment:
.. code-block:: doscon
...\> py -m pip install psycopg

View File

@ -35,7 +35,9 @@ Creating a spatial database
---------------------------
PostGIS 2 includes an extension for PostgreSQL that's used to enable spatial
functionality::
functionality:
.. code-block:: shell
$ createdb <db name>
$ psql <db name>
@ -74,7 +76,9 @@ To administer the database, you can either use the pgAdmin III program
(:menuselection:`Start --> PostgreSQL X --> pgAdmin III`) or the SQL Shell
(:menuselection:`Start --> PostgreSQL X --> SQL Shell`). For example, to create
a ``geodjango`` spatial database and user, the following may be executed from
the SQL Shell as the ``postgres`` user::
the SQL Shell as the ``postgres`` user:
.. code-block:: psql
postgres# CREATE USER geodjango PASSWORD 'my_passwd';
postgres# CREATE DATABASE geodjango OWNER geodjango;

View File

@ -33,7 +33,9 @@ SQLite
------
Check first if SQLite is compiled with the `R*Tree module`__. Run the sqlite3
command line interface and enter the following query::
command line interface and enter the following query:
.. code-block:: sqlite3
sqlite> CREATE VIRTUAL TABLE testrtree USING rtree(id,minX,maxX,minY,maxY);
@ -41,14 +43,18 @@ If you obtain an error, you will have to recompile SQLite from source. Otherwise
skip this section.
To install from sources, download the latest amalgamation source archive from
the `SQLite download page`__, and extract::
the `SQLite download page`__, and extract:
.. code-block:: shell
$ wget https://www.sqlite.org/YYYY/sqlite-amalgamation-XXX0000.zip
$ unzip sqlite-amalgamation-XXX0000.zip
$ cd sqlite-amalgamation-XXX0000
Next, run the ``configure`` script -- however the ``CFLAGS`` environment variable
needs to be customized so that SQLite knows to build the R*Tree module::
needs to be customized so that SQLite knows to build the R*Tree module:
.. code-block:: shell
$ CFLAGS="-DSQLITE_ENABLE_RTREE=1" ./configure
$ make
@ -64,7 +70,9 @@ SpatiaLite library (``libspatialite``)
--------------------------------------
Get the latest SpatiaLite library source bundle from the
`download page`__::
`download page`__:
.. code-block:: shell
$ wget https://www.gaia-gis.it/gaia-sins/libspatialite-sources/libspatialite-X.Y.Z.tar.gz
$ tar xaf libspatialite-X.Y.Z.tar.gz
@ -76,7 +84,9 @@ Get the latest SpatiaLite library source bundle from the
.. note::
For macOS users building from source, the SpatiaLite library *and* tools
need to have their ``target`` configured::
need to have their ``target`` configured:
.. code-block:: shell
$ ./configure --target=macosx
@ -93,7 +103,9 @@ Homebrew
--------
`Homebrew`_ handles all the SpatiaLite related packages on your behalf,
including SQLite, SpatiaLite, PROJ, and GEOS. Install them like this::
including SQLite, SpatiaLite, PROJ, and GEOS. Install them like this:
.. code-block:: shell
$ brew update
$ brew install spatialite-tools

View File

@ -32,7 +32,9 @@ Example
=======
#. You need a GDAL-supported data source, like a shapefile (here we're using
a simple polygon shapefile, ``test_poly.shp``, with three features)::
a simple polygon shapefile, ``test_poly.shp``, with three features):
.. code-block:: pycon
>>> from django.contrib.gis.gdal import DataSource
>>> ds = DataSource('test_poly.shp')
@ -62,7 +64,9 @@ Example
return 'Name: %s' % self.name
#. Use :class:`LayerMapping` to extract all the features and place them in the
database::
database:
.. code-block:: pycon
>>> from django.contrib.gis.utils import LayerMapping
>>> from geoapp.models import TestGeo
@ -206,13 +210,17 @@ should stop excessive memory use when running ``LayerMapping`` scripts.
MySQL: ``max_allowed_packet`` error
-----------------------------------
If you encounter the following error when using ``LayerMapping`` and MySQL::
If you encounter the following error when using ``LayerMapping`` and MySQL:
.. code-block:: pytb
OperationalError: (1153, "Got a packet bigger than 'max_allowed_packet' bytes")
Then the solution is to increase the value of the ``max_allowed_packet``
setting in your MySQL configuration. For example, the default value may
be something low like one megabyte -- the setting may be modified in MySQL's
configuration file (``my.cnf``) in the ``[mysqld]`` section::
configuration file (``my.cnf``) in the ``[mysqld]`` section:
.. code-block:: ini
max_allowed_packet = 10M

View File

@ -16,7 +16,9 @@ Example
:class:`Distance` objects may be instantiated using a keyword argument indicating the
context of the units. In the example below, two different distance objects are
instantiated in units of kilometers (``km``) and miles (``mi``)::
instantiated in units of kilometers (``km``) and miles (``mi``):
.. code-block:: pycon
>>> from django.contrib.gis.measure import D, Distance
>>> d1 = Distance(km=5)
@ -27,7 +29,9 @@ instantiated in units of kilometers (``km``) and miles (``mi``)::
5.0 mi
For conversions, access the preferred unit attribute to get a converted
distance quantity::
distance quantity:
.. code-block:: pycon
>>> print(d1.mi) # Converting 5 kilometers to miles
3.10685596119
@ -35,7 +39,9 @@ distance quantity::
8.04672
Moreover, arithmetic operations may be performed between the distance
objects::
objects:
.. code-block:: pycon
>>> print(d1 + d2) # Adding 5 miles to 5 kilometers
13.04672 km
@ -43,14 +49,18 @@ objects::
1.89314403881 mi
Two :class:`Distance` objects multiplied together will yield an :class:`Area`
object, which uses squared units of measure::
object, which uses squared units of measure:
.. code-block:: pycon
>>> a = d1 * d2 # Returns an Area object.
>>> print(a)
40.2336 sq_km
To determine what the attribute abbreviation of a unit is, the ``unit_attname``
class method may be used::
class method may be used:
.. code-block:: pycon
>>> print(Distance.unit_attname('US Survey Foot'))
survey_ft
@ -117,14 +127,18 @@ Measurement API
To initialize a distance object, pass in a keyword corresponding to the
desired :ref:`unit attribute name <supported_units>` set with desired
value. For example, the following creates a distance object representing 5
miles::
miles:
.. code-block:: pycon
>>> dist = Distance(mi=5)
.. method:: __getattr__(unit_att)
Returns the distance value in units corresponding to the given unit
attribute. For example::
attribute. For example:
.. code-block:: pycon
>>> print(dist.km)
8.04672
@ -132,7 +146,9 @@ Measurement API
.. classmethod:: unit_attname(unit_name)
Returns the distance unit attribute name for the given full unit name. For
example::
example:
.. code-block:: pycon
>>> Distance.unit_attname('Mile')
'mi'
@ -149,14 +165,18 @@ Measurement API
To initialize an area object, pass in a keyword corresponding to the
desired :ref:`unit attribute name <supported_units>` set with desired
value. For example, the following creates an area object representing 5
square miles::
square miles:
.. code-block:: pycon
>>> a = Area(sq_mi=5)
.. method:: __getattr__(unit_att)
Returns the area value in units corresponding to the given unit attribute.
For example::
For example:
.. code-block:: pycon
>>> print(a.sq_km)
12.949940551680001
@ -164,7 +184,9 @@ Measurement API
.. classmethod:: unit_attname(unit_name)
Returns the area unit attribute name for the given full unit name. For
example::
example:
.. code-block:: pycon
>>> Area.unit_attname('Kilometer')
'sq_km'

View File

@ -46,7 +46,9 @@ Create database user
~~~~~~~~~~~~~~~~~~~~
To make a database user with the ability to create databases, use the
following command::
following command:
.. code-block:: shell
$ createuser --createdb -R -S <user_name>
@ -54,19 +56,25 @@ The ``-R -S`` flags indicate that we do not want the user to have the ability
to create additional users (roles) or to be a superuser, respectively.
Alternatively, you may alter an existing user's role from the SQL shell
(assuming this is done from an existing superuser account)::
(assuming this is done from an existing superuser account):
.. code-block:: psql
postgres# ALTER ROLE <user_name> CREATEDB NOSUPERUSER NOCREATEROLE;
Create database superuser
~~~~~~~~~~~~~~~~~~~~~~~~~
This may be done at the time the user is created, for example::
This may be done at the time the user is created, for example:
.. code-block:: shell
$ createuser --superuser <user_name>
Or you may alter the user's role from the SQL shell (assuming this
is done from an existing superuser account)::
is done from an existing superuser account):
.. code-block:: psql
postgres# ALTER ROLE <user_name> SUPERUSER;
@ -114,10 +122,14 @@ in :mod:`django.contrib.gis`::
Assuming the settings above were in a ``postgis.py`` file in the same
directory as ``runtests.py``, then all Django and GeoDjango tests would
be performed when executing the command::
be performed when executing the command:
.. code-block:: shell
$ ./runtests.py --settings=postgis
To run only the GeoDjango test suite, specify ``gis_tests``::
To run only the GeoDjango test suite, specify ``gis_tests``:
.. code-block:: shell
$ ./runtests.py --settings=postgis gis_tests

View File

@ -321,14 +321,18 @@ First, invoke the Django shell:
$ python manage.py shell
If you downloaded the :ref:`worldborders` data earlier in the tutorial, then
you can determine its path using Python's :class:`pathlib.Path`::
you can determine its path using Python's :class:`pathlib.Path`:
.. code-block:: pycon
>>> from pathlib import Path
>>> import world
>>> world_shp = Path(world.__file__).resolve().parent / 'data' / 'TM_WORLD_BORDERS-0.3.shp'
Now, open the world borders shapefile using GeoDjango's
:class:`~django.contrib.gis.gdal.DataSource` interface::
:class:`~django.contrib.gis.gdal.DataSource` interface:
.. code-block:: pycon
>>> from django.contrib.gis.gdal import DataSource
>>> ds = DataSource(world_shp)
@ -336,7 +340,9 @@ Now, open the world borders shapefile using GeoDjango's
/ ... /geodjango/world/data/TM_WORLD_BORDERS-0.3.shp (ESRI Shapefile)
Data source objects can have different layers of geospatial features; however,
shapefiles are only allowed to have one layer::
shapefiles are only allowed to have one layer:
.. code-block:: pycon
>>> print(len(ds))
1
@ -344,7 +350,9 @@ shapefiles are only allowed to have one layer::
>>> print(lyr)
TM_WORLD_BORDERS-0.3
You can see the layer's geometry type and how many features it contains::
You can see the layer's geometry type and how many features it contains:
.. code-block:: pycon
>>> print(lyr.geom_type)
Polygon
@ -363,7 +371,9 @@ You can see the layer's geometry type and how many features it contains::
The :class:`~django.contrib.gis.gdal.Layer` may also have a spatial reference
system associated with it. If it does, the ``srs`` attribute will return a
:class:`~django.contrib.gis.gdal.SpatialReference` object::
:class:`~django.contrib.gis.gdal.SpatialReference` object:
.. code-block:: pycon
>>> srs = lyr.srs
>>> print(srs)
@ -401,7 +411,9 @@ string) associated with each of the fields:
You can iterate over each feature in the layer and extract information from both
the feature's geometry (accessed via the ``geom`` attribute) as well as the
feature's attribute fields (whose **values** are accessed via ``get()``
method)::
method):
.. code-block:: pycon
>>> for feat in lyr:
... print(feat.get('NAME'), feat.geom.num_points)
@ -411,18 +423,24 @@ method)::
South Georgia South Sandwich Islands 338
Taiwan 363
:class:`~django.contrib.gis.gdal.Layer` objects may be sliced::
:class:`~django.contrib.gis.gdal.Layer` objects may be sliced:
.. code-block:: pycon
>>> lyr[0:2]
[<django.contrib.gis.gdal.feature.Feature object at 0x2f47690>, <django.contrib.gis.gdal.feature.Feature object at 0x2f47650>]
And individual features may be retrieved by their feature ID::
And individual features may be retrieved by their feature ID:
.. code-block:: pycon
>>> feat = lyr[234]
>>> print(feat.get('NAME'))
San Marino
Boundary geometries may be exported as WKT and GeoJSON::
Boundary geometries may be exported as WKT and GeoJSON:
.. code-block:: pycon
>>> geom = feat.geom
>>> print(geom.wkt)
@ -484,7 +502,9 @@ Afterward, invoke the Django shell from the ``geodjango`` project directory:
$ python manage.py shell
Next, import the ``load`` module, call the ``run`` routine, and watch
``LayerMapping`` do the work::
``LayerMapping`` do the work:
.. code-block:: pycon
>>> from world import load
>>> load.run()
@ -576,7 +596,9 @@ a particular point. First, fire up the management shell:
$ python manage.py shell
Now, define a point of interest [#]_::
Now, define a point of interest [#]_:
.. code-block:: pycon
>>> pnt_wkt = 'POINT(-95.3385 29.7245)'
@ -584,7 +606,9 @@ The ``pnt_wkt`` string represents the point at -95.3385 degrees longitude,
29.7245 degrees latitude. The geometry is in a format known as
Well Known Text (WKT), a standard issued by the Open Geospatial
Consortium (OGC). [#]_ Import the ``WorldBorder`` model, and perform
a ``contains`` lookup using the ``pnt_wkt`` as the parameter::
a ``contains`` lookup using the ``pnt_wkt`` as the parameter:
.. code-block:: pycon
>>> from world.models import WorldBorder
>>> WorldBorder.objects.filter(mpoly__contains=pnt_wkt)
@ -596,7 +620,9 @@ United States (exactly what you would expect).
Similarly, you may also use a :doc:`GEOS geometry object <geos>`.
Here, you can combine the ``intersects`` spatial lookup with the ``get``
method to retrieve only the ``WorldBorder`` instance for San Marino instead
of a queryset::
of a queryset:
.. code-block:: pycon
>>> from django.contrib.gis.geos import Point
>>> pnt = Point(12.4604, 43.9420)
@ -614,19 +640,25 @@ When doing spatial queries, GeoDjango automatically transforms
geometries if they're in a different coordinate system. In the following
example, coordinates will be expressed in `EPSG SRID 32140`__,
a coordinate system specific to south Texas **only** and in units of
**meters**, not degrees::
**meters**, not degrees:
.. code-block:: pycon
>>> from django.contrib.gis.geos import GEOSGeometry, Point
>>> pnt = Point(954158.1, 4215137.1, srid=32140)
Note that ``pnt`` may also be constructed with EWKT, an "extended" form of
WKT that includes the SRID::
WKT that includes the SRID:
.. code-block:: pycon
>>> pnt = GEOSGeometry('SRID=32140;POINT(954158.1 4215137.1)')
GeoDjango's ORM will automatically wrap geometry values
in transformation SQL, allowing the developer to work at a higher level
of abstraction::
of abstraction:
.. code-block:: pycon
>>> qs = WorldBorder.objects.filter(mpoly__intersects=pnt)
>>> print(qs.query) # Generating the SQL
@ -646,7 +678,9 @@ __ https://spatialreference.org/ref/epsg/32140/
.. admonition:: Raw queries
When using :doc:`raw queries </topics/db/sql>`, you must wrap your geometry
fields so that the field value can be recognized by GEOS::
fields so that the field value can be recognized by GEOS:
.. code-block:: pycon
from django.db import connection
# or if you're querying a non-default database:
@ -663,7 +697,9 @@ GeoDjango loads geometries in a standardized textual representation. When the
geometry field is first accessed, GeoDjango creates a
:class:`~django.contrib.gis.geos.GEOSGeometry` object, exposing powerful
functionality, such as serialization properties for popular geospatial
formats::
formats:
.. code-block:: pycon
>>> sm = WorldBorder.objects.get(name='San Marino')
>>> sm.mpoly
@ -676,7 +712,9 @@ formats::
'{ "type": "MultiPolygon", "coordinates": [ [ [ [ 12.415798, 43.957954 ], [ 12.450554, 43.979721 ], ...
This includes access to all of the advanced geometric operations provided by
the GEOS library::
the GEOS library:
.. code-block:: pycon
>>> pnt = Point(12.4604, 43.9420)
>>> sm.mpoly.contains(pnt)

View File

@ -180,7 +180,9 @@ Displaying messages
-------------------
.. function:: get_messages(request)
**In your template**, use something like::
**In your template**, use something like:
.. code-block:: html+django
{% if messages %}
<ul class="messages">
@ -199,7 +201,9 @@ Even if you know there is only one message, you should still iterate over the
cleared for the next request.
The context processor also provides a ``DEFAULT_MESSAGE_LEVELS`` variable which
is a mapping of the message level names to their numeric value::
is a mapping of the message level names to their numeric value:
.. code-block:: html+django
{% if messages %}
<ul class="messages">

View File

@ -12,7 +12,9 @@ module. They are described in more detail in the `PostgreSQL docs
.. note::
All functions come without default aliases, so you must explicitly provide
one. For example::
one. For example:
.. code-block:: pycon
>>> SomeModel.objects.aggregate(arr=ArrayAgg('somefield'))
{'arr': [0, 1, 2]}
@ -97,6 +99,8 @@ General-purpose aggregation functions
published = models.BooleanField()
rank = models.IntegerField()
.. code-block:: pycon
>>> from django.db.models import Q
>>> from django.contrib.postgres.aggregates import BoolAnd
>>> Comment.objects.aggregate(booland=BoolAnd('published'))
@ -119,6 +123,8 @@ General-purpose aggregation functions
published = models.BooleanField()
rank = models.IntegerField()
.. code-block:: pycon
>>> from django.db.models import Q
>>> from django.contrib.postgres.aggregates import BoolOr
>>> Comment.objects.aggregate(boolor=BoolOr('published'))
@ -160,6 +166,8 @@ General-purpose aggregation functions
end = models.DateTimeField()
requirements = models.JSONField(blank=True, null=True)
.. code-block:: pycon
>>> from django.contrib.postgres.aggregates import JSONBAgg
>>> Room.objects.annotate(
... requirements=JSONBAgg(
@ -213,6 +221,8 @@ General-purpose aggregation functions
headline = models.CharField(max_length=100)
publications = models.ManyToManyField(Publication)
.. code-block:: pycon
>>> article = Article.objects.create(headline="NASA uses Python")
>>> article.publications.create(title="The Python Journal")
<Publication: Publication object (1)>
@ -349,7 +359,9 @@ field or an expression returning a numeric data. Both are required.
Usage examples
==============
We will use this example table::
We will use this example table:
.. code-block:: text
| FIELD1 | FIELD2 | FIELD3 |
|--------|--------|--------|
@ -357,8 +369,9 @@ We will use this example table::
| bar | 2 | (null) |
| test | 3 | 13 |
Here's some examples of some of the general-purpose aggregation functions:
Here's some examples of some of the general-purpose aggregation functions::
.. code-block:: pycon
>>> TestModel.objects.aggregate(result=StringAgg('field1', delimiter=';'))
{'result': 'foo;bar;test'}
@ -369,7 +382,9 @@ Here's some examples of some of the general-purpose aggregation functions::
The next example shows the usage of statistical aggregate functions. The
underlying math will be not described (you can read about this, for example, at
`wikipedia <https://en.wikipedia.org/wiki/Regression_analysis>`_)::
`wikipedia <https://en.wikipedia.org/wiki/Regression_analysis>`_):
.. code-block:: pycon
>>> TestModel.objects.aggregate(count=RegrCount(y='field3', x='field2'))
{'count': 2}

View File

@ -22,7 +22,9 @@ in the way that it does not act as an aggregate function and does not require
an SQL ``GROUP BY`` clause to build the list of values.
For example, if you want to annotate all related books to an author as JSON
objects::
objects:
.. code-block:: pycon
>>> from django.db.models import OuterRef
>>> from django.db.models.functions import JSONObject

View File

@ -127,7 +127,9 @@ We will use the following example model::
The :lookup:`contains` lookup is overridden on :class:`ArrayField`. The
returned objects will be those where the values passed are a subset of the
data. It uses the SQL operator ``@>``. For example::
data. It uses the SQL operator ``@>``. For example:
.. code-block:: pycon
>>> Post.objects.create(name='First post', tags=['thoughts', 'django'])
>>> Post.objects.create(name='Second post', tags=['thoughts'])
@ -149,7 +151,9 @@ data. It uses the SQL operator ``@>``. For example::
This is the inverse of the :lookup:`contains <arrayfield.contains>` lookup -
the objects returned will be those where the data is a subset of the values
passed. It uses the SQL operator ``<@``. For example::
passed. It uses the SQL operator ``<@``. For example:
.. code-block:: pycon
>>> Post.objects.create(name='First post', tags=['thoughts', 'django'])
>>> Post.objects.create(name='Second post', tags=['thoughts'])
@ -167,7 +171,9 @@ passed. It uses the SQL operator ``<@``. For example::
~~~~~~~~~~~
Returns objects where the data shares any results with the values passed. Uses
the SQL operator ``&&``. For example::
the SQL operator ``&&``. For example:
.. code-block:: pycon
>>> Post.objects.create(name='First post', tags=['thoughts', 'django'])
>>> Post.objects.create(name='Second post', tags=['thoughts', 'tutorial'])
@ -193,7 +199,9 @@ the SQL operator ``&&``. For example::
~~~~~~~
Returns the length of the array. The lookups available afterward are those
available for :class:`~django.db.models.IntegerField`. For example::
available for :class:`~django.db.models.IntegerField`. For example:
.. code-block:: pycon
>>> Post.objects.create(name='First post', tags=['thoughts', 'django'])
>>> Post.objects.create(name='Second post', tags=['thoughts'])
@ -209,7 +217,9 @@ Index transforms
Index transforms index into the array. Any non-negative integer can be used.
There are no errors if it exceeds the :attr:`size <ArrayField.size>` of the
array. The lookups available after the transform are those from the
:attr:`base_field <ArrayField.base_field>`. For example::
:attr:`base_field <ArrayField.base_field>`. For example:
.. code-block:: pycon
>>> Post.objects.create(name='First post', tags=['thoughts', 'django'])
>>> Post.objects.create(name='Second post', tags=['thoughts'])
@ -236,7 +246,9 @@ Slice transforms
Slice transforms take a slice of the array. Any two non-negative integers can
be used, separated by a single underscore. The lookups available after the
transform do not change. For example::
transform do not change. For example:
.. code-block:: pycon
>>> Post.objects.create(name='First post', tags=['thoughts', 'django'])
>>> Post.objects.create(name='Second post', tags=['thoughts'])
@ -374,7 +386,9 @@ We will use the following example model::
Key lookups
~~~~~~~~~~~
To query based on a given key, you can use that key as the lookup name::
To query based on a given key, you can use that key as the lookup name:
.. code-block:: pycon
>>> Dog.objects.create(name='Rufus', data={'breed': 'labrador'})
>>> Dog.objects.create(name='Meg', data={'breed': 'collie'})
@ -382,12 +396,16 @@ To query based on a given key, you can use that key as the lookup name::
>>> Dog.objects.filter(data__breed='collie')
<QuerySet [<Dog: Meg>]>
You can chain other lookups after key lookups::
You can chain other lookups after key lookups:
.. code-block:: pycon
>>> Dog.objects.filter(data__breed__contains='l')
<QuerySet [<Dog: Rufus>, <Dog: Meg>]>
or use ``F()`` expressions to annotate a key value. For example::
or use ``F()`` expressions to annotate a key value. For example:
.. code-block:: pycon
>>> from django.db.models import F
>>> rufus = Dog.objects.annotate(breed=F("data__breed"))[0]
@ -419,7 +437,9 @@ need to use the :lookup:`hstorefield.contains` lookup instead.
The :lookup:`contains` lookup is overridden on
:class:`~django.contrib.postgres.fields.HStoreField`. The returned objects are
those where the given ``dict`` of key-value pairs are all contained in the
field. It uses the SQL operator ``@>``. For example::
field. It uses the SQL operator ``@>``. For example:
.. code-block:: pycon
>>> Dog.objects.create(name='Rufus', data={'breed': 'labrador', 'owner': 'Bob'})
>>> Dog.objects.create(name='Meg', data={'breed': 'collie', 'owner': 'Bob'})
@ -439,7 +459,9 @@ field. It uses the SQL operator ``@>``. For example::
This is the inverse of the :lookup:`contains <hstorefield.contains>` lookup -
the objects returned will be those where the key-value pairs on the object are
a subset of those in the value passed. It uses the SQL operator ``<@``. For
example::
example:
.. code-block:: pycon
>>> Dog.objects.create(name='Rufus', data={'breed': 'labrador', 'owner': 'Bob'})
>>> Dog.objects.create(name='Meg', data={'breed': 'collie', 'owner': 'Bob'})
@ -457,7 +479,9 @@ example::
~~~~~~~~~~~
Returns objects where the given key is in the data. Uses the SQL operator
``?``. For example::
``?``. For example:
.. code-block:: pycon
>>> Dog.objects.create(name='Rufus', data={'breed': 'labrador'})
>>> Dog.objects.create(name='Meg', data={'breed': 'collie', 'owner': 'Bob'})
@ -471,7 +495,9 @@ Returns objects where the given key is in the data. Uses the SQL operator
~~~~~~~~~~~~~~~~
Returns objects where any of the given keys are in the data. Uses the SQL
operator ``?|``. For example::
operator ``?|``. For example:
.. code-block:: pycon
>>> Dog.objects.create(name='Rufus', data={'breed': 'labrador'})
>>> Dog.objects.create(name='Meg', data={'owner': 'Bob'})
@ -486,7 +512,9 @@ operator ``?|``. For example::
~~~~~~~~~~~~
Returns objects where all of the given keys are in the data. Uses the SQL operator
``?&``. For example::
``?&``. For example:
.. code-block:: pycon
>>> Dog.objects.create(name='Rufus', data={})
>>> Dog.objects.create(name='Meg', data={'breed': 'collie', 'owner': 'Bob'})
@ -503,7 +531,9 @@ Returns objects where the array of keys is the given value. Note that the order
is not guaranteed to be reliable, so this transform is mainly useful for using
in conjunction with lookups on
:class:`~django.contrib.postgres.fields.ArrayField`. Uses the SQL function
``akeys()``. For example::
``akeys()``. For example:
.. code-block:: pycon
>>> Dog.objects.create(name='Rufus', data={'toy': 'bone'})
>>> Dog.objects.create(name='Meg', data={'breed': 'collie', 'owner': 'Bob'})
@ -520,7 +550,9 @@ Returns objects where the array of values is the given value. Note that the
order is not guaranteed to be reliable, so this transform is mainly useful for
using in conjunction with lookups on
:class:`~django.contrib.postgres.fields.ArrayField`. Uses the SQL function
``avals()``. For example::
``avals()``. For example:
.. code-block:: pycon
>>> Dog.objects.create(name='Rufus', data={'breed': 'labrador'})
>>> Dog.objects.create(name='Meg', data={'breed': 'collie', 'owner': 'Bob'})
@ -642,7 +674,9 @@ model::
def __str__(self):
return self.name
We will also use the following example objects::
We will also use the following example objects:
.. code-block:: pycon
>>> import datetime
>>> from django.utils import timezone
@ -685,7 +719,9 @@ The ``contained_by`` lookup is also available on the non-range field types:
:class:`~django.db.models.BigIntegerField`,
:class:`~django.db.models.DecimalField`, :class:`~django.db.models.FloatField`,
:class:`~django.db.models.DateField`, and
:class:`~django.db.models.DateTimeField`. For example::
:class:`~django.db.models.DateTimeField`. For example:
.. code-block:: pycon
>>> from django.db.backends.postgresql.psycopg_any import DateTimeTZRange
>>> Event.objects.filter(

View File

@ -23,7 +23,9 @@ Fields
It specifies the underlying form field for the array. This is not used
to render any HTML, but it is used to process the submitted data and
validate it. For example::
validate it. For example:
.. code-block:: pycon
>>> from django import forms
>>> from django.contrib.postgres.forms import SimpleArrayField
@ -45,7 +47,9 @@ Fields
This is an optional argument which defaults to a comma: ``,``. This
value is used to split the submitted data. It allows you to chain
``SimpleArrayField`` for multidimensional data::
``SimpleArrayField`` for multidimensional data:
.. code-block:: pycon
>>> from django import forms
>>> from django.contrib.postgres.forms import SimpleArrayField

View File

@ -20,7 +20,9 @@ operation to install it.
.. _pgcrypto extension: https://www.postgresql.org/docs/current/pgcrypto.html
Usage example::
Usage example:
.. code-block:: pycon
>>> from django.contrib.postgres.functions import RandomUUID
>>> Article.objects.update(uuid=RandomUUID())
@ -41,7 +43,9 @@ sets up a transaction and thus sets the time that ``TransactionNow()`` will
return; nested calls create savepoints which do not affect the transaction
time.
Usage example::
Usage example:
.. code-block:: pycon
>>> from django.contrib.postgres.functions import TransactionNow
>>> Article.objects.filter(published__lte=TransactionNow())

View File

@ -23,7 +23,9 @@ extension using the
operation.
The ``trigram_similar`` lookup can be used on
:class:`~django.db.models.CharField` and :class:`~django.db.models.TextField`::
:class:`~django.db.models.CharField` and :class:`~django.db.models.TextField`:
.. code-block:: pycon
>>> City.objects.filter(name__trigram_similar="Middlesborough")
['<City: Middlesbrough>']
@ -47,7 +49,9 @@ extension using the
operation.
The ``trigram_word_similar`` lookup can be used on
:class:`~django.db.models.CharField` and :class:`~django.db.models.TextField`::
:class:`~django.db.models.CharField` and :class:`~django.db.models.TextField`:
.. code-block:: pycon
>>> Sentence.objects.filter(name__trigram_word_similar='Middlesborough')
['<Sentence: Gumby rides on the path of Middlesbrough>']
@ -91,7 +95,9 @@ operation is available if you want to perform this activation using migrations).
.. _unaccent extension on PostgreSQL: https://www.postgresql.org/docs/current/unaccent.html
The ``unaccent`` lookup can be used on
:class:`~django.db.models.CharField` and :class:`~django.db.models.TextField`::
:class:`~django.db.models.CharField` and :class:`~django.db.models.TextField`:
.. code-block:: pycon
>>> City.objects.filter(name__unaccent="México")
['<City: Mexico>']

View File

@ -22,7 +22,9 @@ The ``search`` lookup
.. fieldlookup:: search
A common way to use full text search is to search a single term against a
single column in the database. For example::
single column in the database. For example:
.. code-block:: pycon
>>> Entry.objects.filter(body_text__search='Cheese')
[<Entry: Cheese on Toast recipes>, <Entry: Pizza Recipes>]
@ -42,7 +44,9 @@ To use the ``search`` lookup, ``'django.contrib.postgres'`` must be in your
Searching against a single field is great but rather limiting. The ``Entry``
instances we're searching belong to a ``Blog``, which has a ``tagline`` field.
To query against both fields, use a ``SearchVector``::
To query against both fields, use a ``SearchVector``:
.. code-block:: pycon
>>> from django.contrib.postgres.search import SearchVector
>>> Entry.objects.annotate(
@ -56,7 +60,9 @@ arguments will be concatenated together using a space so that the search
document includes them all.
``SearchVector`` objects can be combined together, allowing you to reuse them.
For example::
For example:
.. code-block:: pycon
>>> Entry.objects.annotate(
... search=SearchVector('body_text') + SearchVector('blog__tagline'),
@ -96,7 +102,9 @@ Examples:
>>> SearchQuery("'tomato' & ('red' | 'green')", search_type='raw') # boolean operators
>>> SearchQuery("'tomato' ('red' OR 'green')", search_type='websearch') # websearch operators
``SearchQuery`` terms can be combined logically to provide more flexibility::
``SearchQuery`` terms can be combined logically to provide more flexibility:
.. code-block:: pycon
>>> from django.contrib.postgres.search import SearchQuery
>>> SearchQuery('meat') & SearchQuery('cheese') # AND
@ -117,7 +125,9 @@ sort of relevancy. PostgreSQL provides a ranking function which takes into
account how often the query terms appear in the document, how close together
the terms are in the document, and how important the part of the document is
where they occur. The better the match, the higher the value of the rank. To
order by relevancy::
order by relevancy:
.. code-block:: pycon
>>> from django.contrib.postgres.search import SearchQuery, SearchRank, SearchVector
>>> vector = SearchVector('body_text')
@ -134,7 +144,9 @@ account.
Provide an integer to the ``normalization`` parameter to control rank
normalization. This integer is a bit mask, so you can combine multiple
behaviors::
behaviors:
.. code-block:: pycon
>>> from django.db.models import Value
>>> Entry.objects.annotate(
@ -182,7 +194,9 @@ between fragments. PostgreSQL's default is ``" ... "``.
The PostgreSQL documentation has more details on `highlighting search
results`_.
Usage example::
Usage example:
.. code-block:: pycon
>>> from django.contrib.postgres.search import SearchHeadline, SearchQuery
>>> query = SearchQuery('red tomato')
@ -209,7 +223,9 @@ Changing the search configuration
You can specify the ``config`` attribute to a :class:`SearchVector` and
:class:`SearchQuery` to use a different search configuration. This allows using
different language parsers and dictionaries as defined by the database::
different language parsers and dictionaries as defined by the database:
.. code-block:: pycon
>>> from django.contrib.postgres.search import SearchQuery, SearchVector
>>> Entry.objects.annotate(
@ -217,7 +233,9 @@ different language parsers and dictionaries as defined by the database::
... ).filter(search=SearchQuery('œuf', config='french'))
[<Entry: Pain perdu>]
The value of ``config`` could also be stored in another column::
The value of ``config`` could also be stored in another column:
.. code-block:: pycon
>>> from django.db.models import F
>>> Entry.objects.annotate(
@ -231,7 +249,9 @@ Weighting queries
=================
Every field may not have the same relevance in a query, so you can set weights
of various vectors before you combine them::
of various vectors before you combine them:
.. code-block:: pycon
>>> from django.contrib.postgres.search import SearchQuery, SearchRank, SearchVector
>>> vector = SearchVector('body_text', weight='A') + SearchVector('blog__tagline', weight='B')
@ -241,7 +261,9 @@ of various vectors before you combine them::
The weight should be one of the following letters: D, C, B, A. By default,
these weights refer to the numbers ``0.1``, ``0.2``, ``0.4``, and ``1.0``,
respectively. If you wish to weight them differently, pass a list of four
floats to :class:`SearchRank` as ``weights`` in the same order above::
floats to :class:`SearchRank` as ``weights`` in the same order above:
.. code-block:: pycon
>>> rank = SearchRank(vector, query, weights=[0.2, 0.4, 0.6, 0.8])
>>> Entry.objects.annotate(rank=rank).filter(rank__gte=0.3).order_by('-rank')
@ -277,7 +299,9 @@ The PostgreSQL documentation has details on
If this approach becomes too slow, you can add a ``SearchVectorField`` to your
model. You'll need to keep it populated with triggers, for example, as
described in the `PostgreSQL documentation`_. You can then query the field as
if it were an annotated ``SearchVector``::
if it were an annotated ``SearchVector``:
.. code-block:: pycon
>>> Entry.objects.update(search_vector=SearchVector('body_text'))
>>> Entry.objects.filter(search_vector='cheese')
@ -307,7 +331,9 @@ operation.
Accepts a field name or expression, and a string or expression. Returns the
trigram similarity between the two arguments.
Usage example::
Usage example:
.. code-block:: pycon
>>> from django.contrib.postgres.search import TrigramSimilarity
>>> Author.objects.create(name='Katy Stevens')
@ -326,7 +352,9 @@ Usage example::
Accepts a string or expression, and a field name or expression. Returns the
trigram word similarity between the two arguments.
Usage example::
Usage example:
.. code-block:: pycon
>>> from django.contrib.postgres.search import TrigramWordSimilarity
>>> Author.objects.create(name='Katy Stevens')
@ -357,7 +385,9 @@ extent boundaries to match word boundaries.
Accepts a field name or expression, and a string or expression. Returns the
trigram distance between the two arguments.
Usage example::
Usage example:
.. code-block:: pycon
>>> from django.contrib.postgres.search import TrigramDistance
>>> Author.objects.create(name='Katy Stevens')
@ -376,7 +406,9 @@ Usage example::
Accepts a string or expression, and a field name or expression. Returns the
trigram word distance between the two arguments.
Usage example::
Usage example:
.. code-block:: pycon
>>> from django.contrib.postgres.search import TrigramWordDistance
>>> Author.objects.create(name='Katy Stevens')

View File

@ -74,7 +74,9 @@ Via the Python API
Redirects are represented by a standard :doc:`Django model </topics/db/models>`,
which lives in :source:`django/contrib/redirects/models.py`. You can access
redirect objects via the :doc:`Django database API </topics/db/queries>`.
For example::
For example:
.. code-block:: pycon
>>> from django.conf import settings
>>> from django.contrib.redirects.models import Redirect

View File

@ -623,7 +623,9 @@ Pinging Google via ``manage.py``
.. django-admin:: ping_google [sitemap_url]
Once the sitemaps application is added to your project, you may also
ping Google using the ``ping_google`` management command::
ping Google using the ``ping_google`` management command:
.. code-block:: shell
python manage.py ping_google [/sitemap.xml]

View File

@ -241,7 +241,9 @@ Getting the current domain for full URLs
Django's ``get_absolute_url()`` convention is nice for getting your objects'
URL without the domain name, but in some cases you might want to display the
full URL -- with ``http://`` and the domain and everything -- for an object.
To do this, you can use the sites framework. An example::
To do this, you can use the sites framework. An example:
.. code-block:: pycon
>>> from django.contrib.sites.models import Site
>>> obj = MyModel.objects.get(id=3)

View File

@ -1004,7 +1004,9 @@ They share this interface:
:meth:`.SyndicationFeed.writeString`
Returns the feed as a string in the given encoding.
For example, to create an Atom 1.0 feed and print it to standard output::
For example, to create an Atom 1.0 feed and print it to standard output:
.. code-block:: pycon
>>> from django.utils import feedgenerator
>>> from datetime import datetime

View File

@ -348,7 +348,9 @@ Django uses PostgreSQL's identity columns to store auto-incrementing primary
keys. An identity column is populated with values from a `sequence`_ that keeps
track of the next available value. Manually assigning a value to an
auto-incrementing field doesn't update the field's sequence, which might later
cause a conflict. For example::
cause a conflict. For example:
.. code-block:: pycon
>>> from django.contrib.auth.models import User
>>> User.objects.create(username='alice', pk=1)
@ -491,7 +493,9 @@ This needs to be done just once for your MySQL server, not per database.
Creating your database
----------------------
You can `create your database`_ using the command-line tools and this SQL::
You can `create your database`_ using the command-line tools and this SQL:
.. code-block:: sql
CREATE DATABASE <dbname> CHARACTER SET utf8;
@ -572,6 +576,8 @@ Here's a sample configuration which uses a MySQL option file::
}
.. code-block:: ini
# my.cnf
[client]
database = NAME
@ -641,7 +647,9 @@ If you're using a hosting service and can't change your server's default
storage engine, you have a couple of options.
* After the tables are created, execute an ``ALTER TABLE`` statement to
convert a table to a new storage engine (such as InnoDB)::
convert a table to a new storage engine (such as InnoDB):
.. code-block:: sql
ALTER TABLE <tablename> ENGINE=INNODB;
@ -721,7 +729,9 @@ includes a fractional indication (e.g. ``DATETIME(6)``).
Django will not upgrade existing columns to include fractional seconds if the
database server supports it. If you want to enable them on an existing database,
it's up to you to either manually update the column on the target database, by
executing a command like::
executing a command like:
.. code-block:: sql
ALTER TABLE `your_table` MODIFY `your_datetime_column` DATETIME(6)
@ -1117,7 +1127,9 @@ database backends to modify its behavior, features, or configuration.
Consider, for example, that you need to change a single database feature.
First, you have to create a new directory with a ``base`` module in it. For
example::
example:
.. code-block:: text
mysite/
...

View File

@ -65,7 +65,9 @@ Determining the version
Run ``django-admin version`` to display the current Django version.
The output follows the schema described in :pep:`440`::
The output follows the schema described in :pep:`440`:
.. code-block:: text
1.4.dev17026
1.4a1
@ -91,7 +93,9 @@ Uses the :doc:`system check framework </ref/checks>` to inspect the entire
Django project for common problems.
By default, all apps will be checked. You can check a subset of apps by
providing a list of app labels as arguments::
providing a list of app labels as arguments:
.. console::
django-admin check auth admin myapp
@ -100,13 +104,17 @@ providing a list of app labels as arguments::
The system check framework performs many different types of checks that are
:ref:`categorized with tags <system-check-builtin-tags>`. You can use these
tags to restrict the checks performed to just those in a particular category.
For example, to perform only models and compatibility checks, run::
For example, to perform only models and compatibility checks, run:
.. console::
django-admin check --tag models --tag compatibility
.. django-admin-option:: --database DATABASE
Specifies the database to run checks requiring database access::
Specifies the database to run checks requiring database access:
.. console::
django-admin check --database default --database other
@ -124,7 +132,9 @@ You can use this option in your local development environment, but since your
local development settings module may not have many of your production settings,
you will probably want to point the ``check`` command at a different settings
module, either by setting the :envvar:`DJANGO_SETTINGS_MODULE` environment
variable, or by passing the ``--settings`` option::
variable, or by passing the ``--settings`` option:
.. console::
django-admin check --deploy --settings=production_settings
@ -158,7 +168,9 @@ are excluded.
Includes `fuzzy translations`_ into compiled files.
Example usage::
Example usage:
.. console::
django-admin compilemessages --locale=pt_BR
django-admin compilemessages --locale=pt_BR --locale=fr -f
@ -176,7 +188,9 @@ Example usage::
Ignores directories matching the given :mod:`glob`-style pattern. Use
multiple times to ignore more.
Example usage::
Example usage:
.. console::
django-admin compilemessages --ignore=cache --ignore=outdated/*/locale
@ -329,7 +343,9 @@ only that model will be excluded, rather than the entire application. You can
also mix application names and model names.
If you want to exclude multiple applications, pass ``--exclude`` more than
once::
once:
.. console::
django-admin dumpdata --exclude=auth --exclude=contenttypes
@ -370,7 +386,9 @@ Fixtures compression
The output file can be compressed with one of the ``bz2``, ``gz``, ``lzma``, or
``xz`` formats by ending the filename with the corresponding extension.
For example, to output the data as a compressed JSON file::
For example, to output the data as a compressed JSON file:
.. console::
django-admin dumpdata -o mydata.json.gz
@ -520,7 +538,9 @@ Loading fixtures from ``stdin``
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
You can use a dash as the fixture name to load input from ``sys.stdin``. For
example::
example:
.. console::
django-admin loaddata --format=json -
@ -529,7 +549,9 @@ is required to specify the :ref:`serialization format <serialization-formats>`
of the input (e.g., ``json`` or ``xml``).
Loading from ``stdin`` is useful with standard input and output redirections.
For example::
For example:
.. console::
django-admin dumpdata --format=json --database=test app_label.ModelName | django-admin loaddata --format=json --database=prod -
@ -564,12 +586,16 @@ Updates the message files for all available languages.
Specifies a list of file extensions to examine (default: ``html``, ``txt``,
``py`` or ``js`` if :option:`--domain` is ``js``).
Example usage::
Example usage:
.. console::
django-admin makemessages --locale=de --extension xhtml
Separate multiple extensions with commas or use ``-e`` or ``--extension``
multiple times::
multiple times:
.. console::
django-admin makemessages --locale=de --extension=html,txt --extension xml
@ -582,7 +608,9 @@ Specifies the locale(s) to process.
Specifies the locale(s) to exclude from processing. If not provided, no locales
are excluded.
Example usage::
Example usage:
.. console::
django-admin makemessages --locale=pt_BR
django-admin makemessages --locale=pt_BR --locale=fr
@ -604,7 +632,9 @@ Specifies the domain of the messages files. Supported options are:
Follows symlinks to directories when looking for new translation strings.
Example usage::
Example usage:
.. console::
django-admin makemessages --locale=de --symlinks
@ -615,7 +645,9 @@ multiple times to ignore more.
These patterns are used by default: ``'CVS'``, ``'.*'``, ``'*~'``, ``'*.pyc'``.
Example usage::
Example usage:
.. console::
django-admin makemessages --locale=en_US --ignore=apps/* --ignore=secret/*.html
@ -919,39 +951,57 @@ Uses IPv6 for the development server. This changes the default IP address from
Examples of using different ports and addresses
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Port 8000 on IP address ``127.0.0.1``::
Port 8000 on IP address ``127.0.0.1``:
.. console::
django-admin runserver
Port 8000 on IP address ``1.2.3.4``::
Port 8000 on IP address ``1.2.3.4``:
.. console::
django-admin runserver 1.2.3.4:8000
Port 7000 on IP address ``127.0.0.1``::
Port 7000 on IP address ``127.0.0.1``:
.. console::
django-admin runserver 7000
Port 7000 on IP address ``1.2.3.4``::
Port 7000 on IP address ``1.2.3.4``:
.. console::
django-admin runserver 1.2.3.4:7000
Port 8000 on IPv6 address ``::1``::
Port 8000 on IPv6 address ``::1``:
.. console::
django-admin runserver -6
Port 7000 on IPv6 address ``::1``::
Port 7000 on IPv6 address ``::1``:
.. console::
django-admin runserver -6 7000
Port 7000 on IPv6 address ``2001:0db8:1234:5678::9``::
Port 7000 on IPv6 address ``2001:0db8:1234:5678::9``:
.. console::
django-admin runserver [2001:0db8:1234:5678::9]:7000
Port 8000 on IPv4 address of host ``localhost``::
Port 8000 on IPv4 address of host ``localhost``:
.. console::
django-admin runserver localhost:8000
Port 8000 on IPv6 address of host ``localhost``::
Port 8000 on IPv6 address of host ``localhost``:
.. console::
django-admin runserver -6 localhost:8000
@ -969,7 +1019,9 @@ you want to configure Django to serve static media, read
.. django-admin:: sendtestemail [email [email ...]]
Sends a test email (to confirm email sending through Django is working) to the
recipient(s) specified. For example::
recipient(s) specified. For example:
.. console::
django-admin sendtestemail foo@example.com bar@example.com
@ -998,16 +1050,22 @@ Starts the Python interactive interpreter.
Specifies the shell to use. By default, Django will use IPython_ or bpython_ if
either is installed. If both are installed, specify which one you want like so:
IPython::
IPython:
.. console::
django-admin shell -i ipython
bpython::
bpython:
.. console::
django-admin shell -i bpython
If you have a "rich" shell installed but want to force use of the "plain"
Python interpreter, use ``python`` as the interface name, like so::
Python interpreter, use ``python`` as the interface name, like so:
.. console::
django-admin shell -i python
@ -1022,7 +1080,9 @@ variable or the ``~/.pythonrc.py`` script is read.
.. django-admin-option:: --command COMMAND, -c COMMAND
Lets you pass a command as a string to execute it as Django, like so::
Lets you pass a command as a string to execute it as Django, like so:
.. console::
django-admin shell --command="import django; print(django.__version__)"
@ -1171,7 +1231,9 @@ If the optional destination is provided, Django will use that existing
directory rather than creating a new one. You can use '.' to denote the current
working directory.
For example::
For example:
.. console::
django-admin startapp myapp /Users/jezdez/Code/myapp
@ -1185,7 +1247,9 @@ an uncompressed archive (``.tar``) or a compressed archive (``.tar.gz``,
``.tlz``, ``.zip``) containing the app template files.
For example, this would look for an app template in the given directory when
creating the ``myapp`` app::
creating the ``myapp`` app:
.. console::
django-admin startapp --template=/Users/jezdez/Code/my_app_template myapp
@ -1194,7 +1258,9 @@ archives with the app template files, downloading and extracting them on the
fly.
For example, taking advantage of GitHub's feature to expose repositories as
zip files, you can use a URL like::
zip files, you can use a URL like:
.. console::
django-admin startapp --template=https://github.com/githubuser/django-app-template/archive/main.zip myapp
@ -1277,7 +1343,9 @@ If the optional destination is provided, Django will use that existing
directory as the project directory, and create ``manage.py`` and the project
package within it. Use '.' to denote the current working directory.
For example::
For example:
.. console::
django-admin startproject myproject /Users/jezdez/Code/myproject_repo
@ -1486,7 +1554,9 @@ Outputs timings, including database setup and total run time.
Runs a Django development server (as in :djadmin:`runserver`) using data from
the given fixture(s).
For example, this command::
For example, this command:
.. console::
django-admin testserver mydata.json
@ -1524,7 +1594,9 @@ exactly the same function as the argument to the :djadmin:`runserver` command.
Examples:
To run the test server on port 7000 with ``fixture1`` and ``fixture2``::
To run the test server on port 7000 with ``fixture1`` and ``fixture2``:
.. console::
django-admin testserver --addrport 7000 fixture1 fixture2
django-admin testserver fixture1 fixture2 --addrport 7000
@ -1533,7 +1605,9 @@ To run the test server on port 7000 with ``fixture1`` and ``fixture2``::
that it doesn't matter whether the options come before or after the fixture
arguments.)
To run on 1.2.3.4:7000 with a ``test`` fixture::
To run on 1.2.3.4:7000 with a ``test`` fixture:
.. console::
django-admin testserver --addrport 1.2.3.4:7000 test
@ -1570,7 +1644,9 @@ the password whose username matches the current user.
Specifies the database to query for the user. Defaults to ``default``.
Example usage::
Example usage:
.. console::
django-admin changepassword ringo
@ -1724,7 +1800,9 @@ variable.
This option is unnecessary in ``manage.py``, because it takes care of setting
the Python path for you.
Example usage::
Example usage:
.. console::
django-admin migrate --pythonpath='/home/djangoprojects/myproject'
@ -1740,7 +1818,9 @@ variable.
This option is unnecessary in ``manage.py``, because it uses
``settings.py`` from the current project by default.
Example usage::
Example usage:
.. console::
django-admin migrate --settings=mysite.settings
@ -1752,7 +1832,9 @@ is raised. By default, ``django-admin`` will show an error message when a
This option is ignored by :djadmin:`runserver`.
Example usage::
Example usage:
.. console::
django-admin migrate --traceback
@ -1768,7 +1850,9 @@ should print to the console.
This option is ignored by :djadmin:`runserver`.
Example usage::
Example usage:
.. console::
django-admin migrate --verbosity 2
@ -1778,7 +1862,9 @@ Disables colorized command output. Some commands format their output to be
colorized. For example, errors will be printed to the console in red and SQL
statements will be syntax highlighted.
Example usage::
Example usage:
.. console::
django-admin runserver --no-color
@ -1795,7 +1881,9 @@ available if the
:attr:`~django.core.management.BaseCommand.requires_system_checks` command
attribute is not an empty list or tuple.
Example usage::
Example usage:
.. console::
django-admin migrate --skip-checks
@ -1828,7 +1916,9 @@ two third-party libraries are needed:
* Install colorama_, a Python package that translates ANSI color codes into
Windows API calls. Django commands will detect its presence and will make use
of its services to color output just like on Unix-based platforms.
``colorama`` can be installed via pip::
``colorama`` can be installed via pip:
.. code-block:: doscon
...\> py -m pip install colorama
@ -1863,7 +1953,9 @@ ships with three color palettes:
You select a palette by setting a :envvar:`DJANGO_COLORS` environment
variable to specify the palette you want to use. For example, to
specify the ``light`` palette under a Unix or OS/X BASH shell, you
would run the following at a command prompt::
would run the following at a command prompt:
.. code-block:: shell
export DJANGO_COLORS="light"
@ -1919,7 +2011,9 @@ A color specification follows one of the following patterns:
where ``role`` is the name of a valid color role, ``fg`` is the
foreground color, ``bg`` is the background color and each ``option``
is one of the color modifying options. Multiple color specifications
are then separated by a semicolon. For example::
are then separated by a semicolon. For example:
.. code-block:: shell
export DJANGO_COLORS="error=yellow/blue,blink;notice=magenta"
@ -1929,7 +2023,9 @@ left uncolored.
Colors can also be specified by extending a base palette. If you put
a palette name in a color specification, all the colors implied by that
palette will be loaded. So::
palette will be loaded. So:
.. code-block:: shell
export DJANGO_COLORS="light;error=yellow/blue,blink;notice=magenta"
@ -1961,11 +2057,15 @@ The Python files created by :djadmin:`startproject`, :djadmin:`startapp`,
present on your ``PATH``.
If you have ``black`` globally installed, but do not wish it used for the
current project, you can set the ``PATH`` explicitly::
current project, you can set the ``PATH`` explicitly:
.. code-block:: shell
PATH=path/to/venv/bin django-admin makemigrations
For commands using ``stdout`` you can pipe the output to ``black`` if needed::
For commands using ``stdout`` you can pipe the output to ``black`` if needed:
.. code-block:: shell
django-admin inspectdb | black -

View File

@ -137,10 +137,14 @@ below) will also have a couple of extra methods:
to point to it. If ``save`` is ``True``, the model's ``save()`` method will
be called once the file is saved. That is, these two lines::
.. code-block:: pycon
>>> car.photo.save('myphoto.jpg', content, save=False)
>>> car.save()
are equivalent to::
are equivalent to:
.. code-block:: pycon
>>> car.photo.save('myphoto.jpg', content, save=True)

View File

@ -25,12 +25,16 @@ A :class:`Form` instance is either **bound** to a set of data, or **unbound**.
.. class:: Form
To create an unbound :class:`Form` instance, instantiate the class::
To create an unbound :class:`Form` instance, instantiate the class:
.. code-block:: pycon
>>> f = ContactForm()
To bind data to a form, pass the data as a dictionary as the first parameter to
your :class:`Form` class constructor::
your :class:`Form` class constructor:
.. code-block:: pycon
>>> data = {'subject': 'hello',
... 'message': 'Hi there',
@ -47,7 +51,9 @@ in a moment.
.. attribute:: Form.is_bound
If you need to distinguish between bound and unbound form instances at runtime,
check the value of the form's :attr:`~Form.is_bound` attribute::
check the value of the form's :attr:`~Form.is_bound` attribute:
.. code-block:: pycon
>>> f = ContactForm()
>>> f.is_bound
@ -56,7 +62,9 @@ check the value of the form's :attr:`~Form.is_bound` attribute::
>>> f.is_bound
True
Note that passing an empty dictionary creates a *bound* form with empty data::
Note that passing an empty dictionary creates a *bound* form with empty data:
.. code-block:: pycon
>>> f = ContactForm({})
>>> f.is_bound
@ -81,7 +89,9 @@ validation for fields that are interdependent. See
The primary task of a :class:`Form` object is to validate data. With a bound
:class:`Form` instance, call the :meth:`~Form.is_valid` method to run validation
and return a boolean designating whether the data was valid::
and return a boolean designating whether the data was valid:
.. code-block:: pycon
>>> data = {'subject': 'hello',
... 'message': 'Hi there',
@ -93,7 +103,9 @@ and return a boolean designating whether the data was valid::
Let's try with some invalid data. In this case, ``subject`` is blank (an error,
because all fields are required by default) and ``sender`` is not a valid
email address::
email address:
.. code-block:: pycon
>>> data = {'subject': '',
... 'message': 'Hi there',
@ -106,7 +118,9 @@ email address::
.. attribute:: Form.errors
Access the :attr:`~Form.errors` attribute to get a dictionary of error
messages::
messages:
.. code-block:: pycon
>>> f.errors
{'sender': ['Enter a valid email address.'], 'subject': ['This field is required.']}
@ -214,7 +228,9 @@ Behavior of unbound forms
-------------------------
It's meaningless to validate a form with no data, but, for the record, here's
what happens with unbound forms::
what happens with unbound forms:
.. code-block:: pycon
>>> f = ContactForm()
>>> f.is_valid()
@ -236,7 +252,9 @@ username of the current session.
To accomplish this, use the :attr:`~Form.initial` argument to a :class:`Form`.
This argument, if given, should be a dictionary mapping field names to initial
values. Only include the fields for which you're specifying an initial value;
it's not necessary to include every field in your form. For example::
it's not necessary to include every field in your form. For example:
.. code-block:: pycon
>>> f = ContactForm(initial={'subject': 'Hi there!'})
@ -247,7 +265,9 @@ If a :class:`~django.forms.Field` defines :attr:`~Field.initial` *and* you
include :attr:`~Form.initial` when instantiating the ``Form``, then the latter
``initial`` will have precedence. In this example, ``initial`` is provided both
at the field level and at the form instance level, and the latter gets
precedence::
precedence:
.. code-block:: pycon
>>> from django import forms
>>> class CommentForm(forms.Form):
@ -271,7 +291,9 @@ It is recommended to use :attr:`BoundField.initial` over
simpler interface. Also, unlike :meth:`~Form.get_initial_for_field()`,
:attr:`BoundField.initial` caches its values. This is useful especially when
dealing with callables whose return values can change (e.g. ``datetime.now`` or
``uuid.uuid4``)::
``uuid.uuid4``):
.. code-block:: pycon
>>> import uuid
>>> class UUIDCommentForm(CommentForm):
@ -332,7 +354,9 @@ Accessing the fields from the form
.. attribute:: Form.fields
You can access the fields of :class:`Form` instance from its ``fields``
attribute::
attribute:
.. code-block:: pycon
>>> for row in f.fields.values(): print(row)
...
@ -343,7 +367,9 @@ attribute::
<django.forms.fields.CharField object at 0x7ffaac6324d0>
You can alter the field and :class:`.BoundField` of :class:`Form` instance to
change the way it is presented in the form::
change the way it is presented in the form:
.. code-block:: pycon
>>> f.as_div().split("</div>")[0]
'<div><label for="id_subject">Subject:</label><input type="text" name="subject" maxlength="100" required id="id_subject">'
@ -353,7 +379,9 @@ change the way it is presented in the form::
Beware not to alter the ``base_fields`` attribute because this modification
will influence all subsequent ``ContactForm`` instances within the same Python
process::
process:
.. code-block:: pycon
>>> f.base_fields["subject"].label_suffix = "?"
>>> another_f = CommentForm(auto_id=False)
@ -377,7 +405,9 @@ formats, ``DateField`` will always normalize it to a ``datetime.date`` object
as long as it's valid.
Once you've created a :class:`~Form` instance with a set of data and validated
it, you can access the clean data via its ``cleaned_data`` attribute::
it, you can access the clean data via its ``cleaned_data`` attribute:
.. code-block:: pycon
>>> data = {'subject': 'hello',
... 'message': 'Hi there',
@ -394,7 +424,9 @@ always cleans the input into a string. We'll cover the encoding implications
later in this document.
If your data does *not* validate, the ``cleaned_data`` dictionary contains
only the valid fields::
only the valid fields:
.. code-block:: pycon
>>> data = {'subject': '',
... 'message': 'Hi there',
@ -409,7 +441,9 @@ only the valid fields::
``cleaned_data`` will always *only* contain a key for fields defined in the
``Form``, even if you pass extra data when you define the ``Form``. In this
example, we pass a bunch of extra fields to the ``ContactForm`` constructor,
but ``cleaned_data`` contains only the form's fields::
but ``cleaned_data`` contains only the form's fields:
.. code-block:: pycon
>>> data = {'subject': 'hello',
... 'message': 'Hi there',
@ -427,7 +461,9 @@ but ``cleaned_data`` contains only the form's fields::
When the ``Form`` is valid, ``cleaned_data`` will include a key and value for
*all* its fields, even if the data didn't include a value for some optional
fields. In this example, the data dictionary doesn't include a value for the
``nick_name`` field, but ``cleaned_data`` includes it, with an empty value::
``nick_name`` field, but ``cleaned_data`` includes it, with an empty value:
.. code-block:: pycon
>>> from django import forms
>>> class OptionalPersonForm(forms.Form):
@ -458,7 +494,9 @@ Outputting forms as HTML
========================
The second task of a ``Form`` object is to render itself as HTML. To do so,
``print`` it::
``print`` it:
.. code-block:: pycon
>>> f = ContactForm()
>>> print(f)
@ -471,7 +509,9 @@ If the form is bound to data, the HTML output will include that data
appropriately. For example, if a field is represented by an
``<input type="text">``, the data will be in the ``value`` attribute. If a
field is represented by an ``<input type="checkbox">``, then that HTML will
include ``checked`` if appropriate::
include ``checked`` if appropriate:
.. code-block:: pycon
>>> data = {'subject': 'hello',
... 'message': 'Hi there',
@ -649,7 +689,9 @@ The template used by ``as_p()``. Default: ``'django/forms/p.html'``.
.. method:: Form.as_p()
``as_p()`` renders the form as a series of ``<p>`` tags, with each ``<p>``
containing one field::
containing one field:
.. code-block:: pycon
>>> f = ContactForm()
>>> f.as_p()
@ -671,7 +713,9 @@ The template used by ``as_ul()``. Default: ``'django/forms/ul.html'``.
``as_ul()`` renders the form as a series of ``<li>`` tags, with each ``<li>``
containing one field. It does *not* include the ``<ul>`` or ``</ul>``, so that
you can specify any HTML attributes on the ``<ul>`` for flexibility::
you can specify any HTML attributes on the ``<ul>`` for flexibility:
.. code-block:: pycon
>>> f = ContactForm()
>>> f.as_ul()
@ -691,7 +735,9 @@ The template used by ``as_table()``. Default: ``'django/forms/table.html'``.
.. method:: Form.as_table()
``as_table()`` renders the form as an HTML ``<table>``::
``as_table()`` renders the form as an HTML ``<table>``:
.. code-block:: pycon
>>> f = ContactForm()
>>> f.as_table()
@ -728,7 +774,9 @@ attributes::
# ... and the rest of your fields here
Once you've done that, rows will be given ``"error"`` and/or ``"required"``
classes, as needed. The HTML will look something like::
classes, as needed. The HTML will look something like:
.. code-block:: pycon
>>> f = ContactForm(data)
>>> print(f.as_table())
@ -770,7 +818,9 @@ Use the ``auto_id`` argument to the ``Form`` constructor to control the ``id``
and label behavior. This argument must be ``True``, ``False`` or a string.
If ``auto_id`` is ``False``, then the form output will not include ``<label>``
tags nor ``id`` attributes::
tags nor ``id`` attributes:
.. code-block:: pycon
>>> f = ContactForm(auto_id=False)
>>> print(f.as_div())
@ -781,7 +831,9 @@ tags nor ``id`` attributes::
If ``auto_id`` is set to ``True``, then the form output *will* include
``<label>`` tags and will use the field name as its ``id`` for each form
field::
field:
.. code-block:: pycon
>>> f = ContactForm(auto_id=True)
>>> print(f.as_div())
@ -794,7 +846,9 @@ If ``auto_id`` is set to a string containing the format character ``'%s'``,
then the form output will include ``<label>`` tags, and will generate ``id``
attributes based on the format string. For example, for a format string
``'field_%s'``, a field named ``subject`` will get the ``id`` value
``'field_subject'``. Continuing our example::
``'field_subject'``. Continuing our example:
.. code-block:: pycon
>>> f = ContactForm(auto_id='id_for_%s')
>>> print(f.as_div())
@ -814,7 +868,9 @@ A translatable string (defaults to a colon (``:``) in English) that will be
appended after any label name when a form is rendered.
It's possible to customize that character, or omit it entirely, using the
``label_suffix`` parameter::
``label_suffix`` parameter:
.. code-block:: pycon
>>> f = ContactForm(auto_id='id_for_%s', label_suffix='')
>>> print(f.as_div())
@ -907,7 +963,9 @@ If you render a bound ``Form`` object, the act of rendering will automatically
run the form's validation if it hasn't already happened, and the HTML output
will include the validation errors as a ``<ul class="errorlist">`` near the
field. The particular positioning of the error messages depends on the output
method you're using::
method you're using:
.. code-block:: pycon
>>> data = {'subject': '',
... 'message': 'Hi there',
@ -1029,13 +1087,17 @@ they're not the only way a form object can be displayed.
The ``__str__()`` method of this object displays the HTML for this field.
To retrieve a single ``BoundField``, use dictionary lookup syntax on your form
using the field's name as the key::
using the field's name as the key:
.. code-block:: pycon
>>> form = ContactForm()
>>> print(form['subject'])
<input id="id_subject" type="text" name="subject" maxlength="100" required>
To retrieve all ``BoundField`` objects, iterate the form::
To retrieve all ``BoundField`` objects, iterate the form:
.. code-block:: pycon
>>> form = ContactForm()
>>> for boundfield in form: print(boundfield)
@ -1044,7 +1106,9 @@ To retrieve all ``BoundField`` objects, iterate the form::
<input type="email" name="sender" id="id_sender" required>
<input type="checkbox" name="cc_myself" id="id_cc_myself">
The field-specific output honors the form object's ``auto_id`` setting::
The field-specific output honors the form object's ``auto_id`` setting:
.. code-block:: pycon
>>> f = ContactForm(auto_id=False)
>>> print(f['message'])
@ -1065,7 +1129,9 @@ Attributes of ``BoundField``
This property returns the data for this :class:`~django.forms.BoundField`
extracted by the widget's :meth:`~django.forms.Widget.value_from_datadict`
method, or ``None`` if it wasn't given::
method, or ``None`` if it wasn't given:
.. code-block:: pycon
>>> unbound_form = ContactForm()
>>> print(unbound_form['subject'].data)
@ -1077,7 +1143,9 @@ Attributes of ``BoundField``
.. attribute:: BoundField.errors
A :ref:`list-like object <ref-forms-error-list-format>` that is displayed
as an HTML ``<ul class="errorlist">`` when printed::
as an HTML ``<ul class="errorlist">`` when printed:
.. code-block:: pycon
>>> data = {'subject': 'hi', 'message': '', 'sender': '', 'cc_myself': ''}
>>> f = ContactForm(data, auto_id=False)
@ -1146,7 +1214,9 @@ Attributes of ``BoundField``
:attr:`BoundField.initial` caches its return value, which is useful
especially when dealing with callables whose return values can change (e.g.
``datetime.now`` or ``uuid.uuid4``)::
``datetime.now`` or ``uuid.uuid4``):
.. code-block:: pycon
>>> from datetime import datetime
>>> class DatedCommentForm(CommentForm):
@ -1172,7 +1242,9 @@ Attributes of ``BoundField``
.. attribute:: BoundField.name
The name of this field in the form::
The name of this field in the form:
.. code-block:: pycon
>>> f = ContactForm()
>>> print(f['subject'].name)
@ -1188,7 +1260,9 @@ Attributes of ``BoundField``
Returns the lowercased class name of the wrapped field's widget, with any
trailing ``input`` or ``widget`` removed. This may be used when building
forms where the layout is dependent upon the widget type. For example::
forms where the layout is dependent upon the widget type. For example:
.. code-block:: html+django
{% for field in form %}
{% if field.widget_type == 'checkbox' %}
@ -1224,7 +1298,9 @@ Methods of ``BoundField``
When you use Django's rendering shortcuts, CSS classes are used to
indicate required form fields or fields that contain errors. If you're
manually rendering a form, you can access these CSS classes using the
``css_classes`` method::
``css_classes`` method:
.. code-block:: pycon
>>> f = ContactForm(data={'message': ''})
>>> f['message'].css_classes()
@ -1232,7 +1308,9 @@ Methods of ``BoundField``
If you want to provide some additional classes in addition to the
error and required classes that may be required, you can provide
those classes as an argument::
those classes as an argument:
.. code-block:: pycon
>>> f = ContactForm(data={'message': ''})
>>> f['message'].css_classes('foo bar')
@ -1265,7 +1343,9 @@ Methods of ``BoundField``
the field you declare, e.g. ``forms.CharField``.
To separately render the label tag of a form field, you can call its
``label_tag()`` method::
``label_tag()`` method:
.. code-block:: pycon
>>> f = ContactForm(data={'message': ''})
>>> print(f['message'].label_tag())
@ -1286,7 +1366,9 @@ Methods of ``BoundField``
.. method:: BoundField.value()
Use this method to render the raw value of this field as it would be rendered
by a ``Widget``::
by a ``Widget``:
.. code-block:: pycon
>>> initial = {'subject': 'welcome'}
>>> unbound_form = ContactForm(initial=initial)
@ -1346,7 +1428,9 @@ is a little more complicated than a normal form.
Firstly, in order to upload files, you'll need to make sure that your
``<form>`` element correctly defines the ``enctype`` as
``"multipart/form-data"``::
``"multipart/form-data"``:
.. code-block:: html
<form enctype="multipart/form-data" method="post" action="/foo/">
@ -1355,7 +1439,9 @@ data is handled separately to normal form data, so when your form
contains a ``FileField`` and ``ImageField``, you will need to specify
a second argument when you bind your form. So if we extend our
ContactForm to include an ``ImageField`` called ``mugshot``, we
need to bind the file data containing the mugshot image::
need to bind the file data containing the mugshot image:
.. code-block:: pycon
# Bound form with an image field
>>> from django.core.files.uploadedfile import SimpleUploadedFile
@ -1368,13 +1454,17 @@ need to bind the file data containing the mugshot image::
In practice, you will usually specify ``request.FILES`` as the source
of file data (just like you use ``request.POST`` as the source of
form data)::
form data):
.. code-block:: pycon
# Bound form with an image field, data from the request
>>> f = ContactFormWithMugshot(request.POST, request.FILES)
Constructing an unbound form is the same as always -- omit both form data *and*
file data::
file data:
.. code-block:: pycon
# Unbound form with an image field
>>> f = ContactFormWithMugshot()
@ -1386,13 +1476,17 @@ Testing for multipart forms
If you're writing reusable views or templates, you may not know ahead of time
whether your form is a multipart form or not. The ``is_multipart()`` method
tells you whether the form requires multipart encoding for submission::
tells you whether the form requires multipart encoding for submission:
.. code-block:: pycon
>>> f = ContactFormWithMugshot()
>>> f.is_multipart()
True
Here's an example of how you might use this in a template::
Here's an example of how you might use this in a template:
.. code-block:: html+django
{% if form.is_multipart %}
<form enctype="multipart/form-data" method="post" action="/foo/">
@ -1414,7 +1508,9 @@ in the subclass.
In this example, ``ContactFormWithPriority`` contains all the fields from
``ContactForm``, plus an additional field, ``priority``. The ``ContactForm``
fields are ordered first::
fields are ordered first:
.. code-block:: pycon
>>> class ContactFormWithPriority(ContactForm):
... priority = forms.CharField()
@ -1429,7 +1525,9 @@ fields are ordered first::
It's possible to subclass multiple forms, treating forms as mixins. In this
example, ``BeatleForm`` subclasses both ``PersonForm`` and ``InstrumentForm``
(in that order), and its field list includes the fields from the parent
classes::
classes:
.. code-block:: pycon
>>> from django import forms
>>> class PersonForm(forms.Form):
@ -1447,7 +1545,9 @@ classes::
<div>Haircut type:<input type="text" name="haircut_type" required></div>
It's possible to declaratively remove a ``Field`` inherited from a parent class
by setting the name of the field to ``None`` on the subclass. For example::
by setting the name of the field to ``None`` on the subclass. For example:
.. code-block:: pycon
>>> from django import forms
@ -1469,7 +1569,9 @@ Prefixes for forms
.. attribute:: Form.prefix
You can put several Django forms inside one ``<form>`` tag. To give each
``Form`` its own namespace, use the ``prefix`` keyword argument::
``Form`` its own namespace, use the ``prefix`` keyword argument:
.. code-block:: pycon
>>> mother = PersonForm(prefix="mother")
>>> father = PersonForm(prefix="father")
@ -1480,7 +1582,9 @@ You can put several Django forms inside one ``<form>`` tag. To give each
<div><label for="id_father-first_name">First name:</label><input type="text" name="father-first_name" required id="id_father-first_name"></div>
<div><label for="id_father-last_name">Last name:</label><input type="text" name="father-last_name" required id="id_father-last_name"></div>
The prefix can also be specified on the form class::
The prefix can also be specified on the form class:
.. code-block:: pycon
>>> class PersonForm(forms.Form):
... ...

View File

@ -20,7 +20,9 @@ you can also instantiate them and use them directly to get a better idea of
how they work. Each ``Field`` instance has a ``clean()`` method, which takes
a single argument and either raises a
``django.core.exceptions.ValidationError`` exception or returns the clean
value::
value:
.. code-block:: pycon
>>> from django import forms
>>> f = forms.EmailField()
@ -47,7 +49,9 @@ should *always* be accepted:
By default, each ``Field`` class assumes the value is required, so if you pass
an empty value -- either ``None`` or the empty string (``""``) -- then
``clean()`` will raise a ``ValidationError`` exception::
``clean()`` will raise a ``ValidationError`` exception:
.. code-block:: pycon
>>> from django import forms
>>> f = forms.CharField()
@ -71,7 +75,9 @@ an empty value -- either ``None`` or the empty string (``""``) -- then
'False'
To specify that a field is *not* required, pass ``required=False`` to the
``Field`` constructor::
``Field`` constructor:
.. code-block:: pycon
>>> f = forms.CharField(required=False)
>>> f.clean('foo')
@ -112,7 +118,9 @@ spaces and upper-casing the first letter. Specify ``label`` if that default
behavior doesn't result in an adequate label.
Here's a full example ``Form`` that implements ``label`` for two of its fields.
We've specified ``auto_id=False`` to simplify the output::
We've specified ``auto_id=False`` to simplify the output:
.. code-block:: pycon
>>> from django import forms
>>> class CommentForm(forms.Form):
@ -131,7 +139,9 @@ We've specified ``auto_id=False`` to simplify the output::
.. attribute:: Field.label_suffix
The ``label_suffix`` argument lets you override the form's
:attr:`~django.forms.Form.label_suffix` on a per-field basis::
:attr:`~django.forms.Form.label_suffix` on a per-field basis:
.. code-block:: pycon
>>> class ContactForm(forms.Form):
... age = forms.IntegerField()
@ -154,7 +164,9 @@ rendering this ``Field`` in an unbound ``Form``.
To specify dynamic initial data, see the :attr:`Form.initial` parameter.
The use-case for this is when you want to display an "empty" form in which a
field is initialized to a particular value. For example::
field is initialized to a particular value. For example:
.. code-block:: pycon
>>> from django import forms
>>> class CommentForm(forms.Form):
@ -169,7 +181,9 @@ field is initialized to a particular value. For example::
You may be thinking, why not just pass a dictionary of the initial values as
data when displaying the form? Well, if you do that, you'll trigger validation,
and the HTML output will include any validation errors::
and the HTML output will include any validation errors:
.. code-block:: pycon
>>> class CommentForm(forms.Form):
... name = forms.CharField()
@ -187,7 +201,9 @@ forms, the HTML output will use the bound data.
Also note that ``initial`` values are *not* used as "fallback" data in
validation if a particular field's value is not given. ``initial`` values are
*only* intended for initial form display::
*only* intended for initial form display:
.. code-block:: pycon
>>> class CommentForm(forms.Form):
... name = forms.CharField(initial='Your name')
@ -201,7 +217,9 @@ validation if a particular field's value is not given. ``initial`` values are
>>> f.errors
{'url': ['This field is required.'], 'name': ['This field is required.']}
Instead of a constant, you can also pass any callable::
Instead of a constant, you can also pass any callable:
.. code-block:: pycon
>>> import datetime
>>> class DateForm(forms.Form):
@ -233,7 +251,9 @@ Like the model field's :attr:`~django.db.models.Field.help_text`, this value
isn't HTML-escaped in automatically-generated forms.
Here's a full example ``Form`` that implements ``help_text`` for two of its
fields. We've specified ``auto_id=False`` to simplify the output::
fields. We've specified ``auto_id=False`` to simplify the output:
.. code-block:: pycon
>>> from django import forms
>>> class HelpTextContactForm(forms.Form):
@ -265,7 +285,9 @@ fields. We've specified ``auto_id=False`` to simplify the output::
The ``error_messages`` argument lets you override the default messages that the
field will raise. Pass in a dictionary with keys matching the error messages you
want to override. For example, here is the default error message::
want to override. For example, here is the default error message:
.. code-block:: pycon
>>> from django import forms
>>> generic = forms.CharField()
@ -274,7 +296,9 @@ want to override. For example, here is the default error message::
...
ValidationError: ['This field is required.']
And here is a custom error message::
And here is a custom error message:
.. code-block:: pycon
>>> name = forms.CharField(error_messages={'required': 'Please enter your name'})
>>> name.clean('')
@ -463,15 +487,15 @@ For each field, we describe the default widget used if you don't specify
The field always accepts strings in ISO 8601 formatted dates or similar
recognized by :func:`~django.utils.dateparse.parse_datetime`. Some examples
are::
are:
* '2006-10-25 14:30:59'
* '2006-10-25T14:30:59'
* '2006-10-25 14:30'
* '2006-10-25T14:30'
* '2006-10-25T14:30Z'
* '2006-10-25T14:30+02:00'
* '2006-10-25'
* ``'2006-10-25 14:30:59'``
* ``'2006-10-25T14:30:59'``
* ``'2006-10-25 14:30'``
* ``'2006-10-25T14:30'``
* ``'2006-10-25T14:30Z'``
* ``'2006-10-25T14:30+02:00'``
* ``'2006-10-25'``
If no ``input_formats`` argument is provided, the default input formats are
taken from the active locale format ``DATETIME_INPUT_FORMATS`` and
@ -723,7 +747,9 @@ For each field, we describe the default widget used if you don't specify
non-image data attributes, such as ``format``, ``height``, and ``width``,
are available, methods that access the underlying image data, such as
``getdata()`` or ``getpixel()``, cannot be used without reopening the file.
For example::
For example:
.. code-block:: pycon
>>> from PIL import Image
>>> from django import forms

View File

@ -86,7 +86,9 @@ buttons.
:class:`Select` widgets are used by default on :class:`ChoiceField` fields. The
choices displayed on the widget are inherited from the :class:`ChoiceField` and
changing :attr:`ChoiceField.choices` will update :attr:`Select.choices`. For
example::
example:
.. code-block:: pycon
>>> from django import forms
>>> CHOICES = [('1', 'First'), ('2', 'Second')]
@ -137,7 +139,9 @@ For example, take the following form::
This form will include three default :class:`TextInput` widgets, with default
rendering -- no CSS class, no extra attributes. This means that the input boxes
provided for each widget will be rendered exactly the same::
provided for each widget will be rendered exactly the same:
.. code-block:: pycon
>>> f = CommentForm(auto_id=False)
>>> f.as_table()
@ -232,7 +236,9 @@ foundation for custom widgets.
'<input title="Your name" type="text" name="name" value="A name" size="10">'
If you assign a value of ``True`` or ``False`` to an attribute,
it will be rendered as an HTML5 boolean attribute::
it will be rendered as an HTML5 boolean attribute:
.. code-block:: pycon
>>> name = forms.TextInput(attrs={'required': True})
>>> name.render('name', 'A name')
@ -361,7 +367,9 @@ foundation for custom widgets.
.. attribute:: MultiWidget.widgets
An iterable containing the widgets needed. For example::
An iterable containing the widgets needed. For example:
.. code-block:: pycon
>>> from django.forms import MultiWidget, TextInput
>>> widget = MultiWidget(widgets=[TextInput, TextInput])
@ -373,7 +381,9 @@ foundation for custom widgets.
``(key, widget)`` pair, the key will be appended to the ``name`` of the
widget in order to generate the attribute value. You may provide the
empty string (``''``) for a single key, in order to suppress the suffix
for one widget. For example::
for one widget. For example:
.. code-block:: pycon
>>> widget = MultiWidget(widgets={'': TextInput, 'last': TextInput})
>>> widget.render('name', ['john', 'paul'])

View File

@ -48,7 +48,9 @@ objects that have an ``output_field`` that is a
:class:`~django.db.models.BooleanField`. The result is provided using the
``then`` keyword.
Some examples::
Some examples:
.. code-block:: pycon
>>> from django.db.models import F, Q, When
>>> # String arguments refer to fields; the following two examples are equivalent:
@ -83,7 +85,9 @@ Keep in mind that each of these values can be an expression.
Since the ``then`` keyword argument is reserved for the result of the
``When()``, there is a potential conflict if a
:class:`~django.db.models.Model` has a field named ``then``. This can be
resolved in two ways::
resolved in two ways:
.. code-block:: pycon
>>> When(then__exact=0, then=1)
>>> When(Q(then=0), then=1)
@ -99,7 +103,9 @@ A ``Case()`` expression is like the :keyword:`if` ... :keyword:`elif` ...
truthful value. The ``result`` expression from the matching ``When()`` object
is returned.
An example::
An example:
.. code-block:: pycon
>>>
>>> from datetime import date, timedelta
@ -133,7 +139,9 @@ argument is returned. If a ``default`` argument isn't provided, ``None`` is
used.
If we wanted to change our previous query to get the discount based on how long
the ``Client`` has been with us, we could do so using lookups::
the ``Client`` has been with us, we could do so using lookups:
.. code-block:: pycon
>>> a_month_ago = date.today() - timedelta(days=30)
>>> a_year_ago = date.today() - timedelta(days=365)
@ -156,7 +164,9 @@ the ``Client`` has been with us, we could do so using lookups::
``Case()`` also works in a ``filter()`` clause. For example, to find gold
clients that registered more than a month ago and platinum clients that
registered more than a year ago::
registered more than a year ago:
.. code-block:: pycon
>>> a_month_ago = date.today() - timedelta(days=30)
>>> a_year_ago = date.today() - timedelta(days=365)
@ -180,7 +190,9 @@ Conditional update
Let's say we want to change the ``account_type`` for our clients to match
their registration dates. We can do this using a conditional expression and the
:meth:`~django.db.models.query.QuerySet.update` method::
:meth:`~django.db.models.query.QuerySet.update` method:
.. code-block:: pycon
>>> a_month_ago = date.today() - timedelta(days=30)
>>> a_year_ago = date.today() - timedelta(days=365)
@ -204,7 +216,9 @@ Conditional aggregation
What if we want to find out how many clients there are for each
``account_type``? We can use the ``filter`` argument of :ref:`aggregate
functions <aggregation-functions>` to achieve this::
functions <aggregation-functions>` to achieve this:
.. code-block:: pycon
>>> # Create some more Clients first so we can have something to count
>>> Client.objects.create(
@ -255,7 +269,9 @@ Conditional filter
When a conditional expression returns a boolean value, it is possible to use it
directly in filters. This means that it will not be added to the ``SELECT``
columns, but you can still use it to filter results::
columns, but you can still use it to filter results:
.. code-block:: pycon
>>> non_unique_account_type = Client.objects.filter(
... account_type=OuterRef('account_type'),

View File

@ -35,7 +35,9 @@ Comparison and conversion functions
Forces the result type of ``expression`` to be the one from ``output_field``.
Usage example::
Usage example:
.. code-block:: pycon
>>> from django.db.models import FloatField
>>> from django.db.models.functions import Cast
@ -56,7 +58,9 @@ first non-null value (note that an empty string is not considered a null
value). Each argument must be of a similar type, so mixing text and numbers
will result in a database error.
Usage examples::
Usage examples:
.. code-block:: pycon
>>> # Get a screen name from least to most public
>>> from django.db.models import Sum
@ -99,12 +103,16 @@ Usage examples::
Takes an expression and a collation name to query against.
For example, to filter case-insensitively in SQLite::
For example, to filter case-insensitively in SQLite:
.. code-block:: pycon
>>> Author.objects.filter(name=Collate(Value('john'), 'nocase'))
<QuerySet [<Author: John>, <Author: john>]>
It can also be used when ordering, for example with PostgreSQL::
It can also be used when ordering, for example with PostgreSQL:
.. code-block:: pycon
>>> Author.objects.order_by(Collate('name', 'et-x-icu'))
<QuerySet [<Author: Ursula>, <Author: Veronika>, <Author: Ülle>]>
@ -129,6 +137,8 @@ Usage example::
modified = models.DateTimeField(auto_now=True)
blog = models.ForeignKey(Blog, on_delete=models.CASCADE)
.. code-block:: pycon
>>> from django.db.models.functions import Greatest
>>> blog = Blog.objects.create(body='Greatest is the best.')
>>> comment = Comment.objects.create(body='No, Least is better.', blog=blog)
@ -159,7 +169,9 @@ and ``comment.modified``.
Takes a list of key-value pairs and returns a JSON object containing those
pairs.
Usage example::
Usage example:
.. code-block:: pycon
>>> from django.db.models import F
>>> from django.db.models.functions import JSONObject, Lower
@ -272,7 +284,9 @@ returned when this timezone is active will be the same as above except for:
databases and from Python's standard functions. This function will return
``1`` for Sunday, ``2`` for Monday, through ``7`` for Saturday.
The equivalent calculation in Python is::
The equivalent calculation in Python is:
.. code-block:: pycon
>>> from datetime import datetime
>>> dt = datetime(2015, 6, 15)
@ -292,7 +306,9 @@ Each ``lookup_name`` above has a corresponding ``Extract`` subclass (listed
below) that should typically be used instead of the more verbose equivalent,
e.g. use ``ExtractYear(...)`` rather than ``Extract(..., lookup_name='year')``.
Usage example::
Usage example:
.. code-block:: pycon
>>> from datetime import datetime
>>> from django.db.models.functions import Extract
@ -356,7 +372,9 @@ class is also a ``Transform`` registered on ``DateField`` and ``DateTimeField``
as ``__(lookup_name)``, e.g. ``__year``.
Since ``DateField``\s don't have a time component, only ``Extract`` subclasses
that deal with date-parts can be used with ``DateField``::
that deal with date-parts can be used with ``DateField``:
.. code-block:: pycon
>>> from datetime import datetime, timezone
>>> from django.db.models.functions import (
@ -406,7 +424,9 @@ These are logically equivalent to ``Extract('datetime_field', lookup_name)``.
Each class is also a ``Transform`` registered on ``DateTimeField`` as
``__(lookup_name)``, e.g. ``__minute``.
``DateTimeField`` examples::
``DateTimeField`` examples:
.. code-block:: pycon
>>> from datetime import datetime, timezone
>>> from django.db.models.functions import (
@ -443,7 +463,9 @@ When :setting:`USE_TZ` is ``True`` then datetimes are stored in the database
in UTC. If a different timezone is active in Django, the datetime is converted
to that timezone before the value is extracted. The example below converts to
the Melbourne timezone (UTC +10:00), which changes the day, weekday, and hour
values that are returned::
values that are returned:
.. code-block:: pycon
>>> from django.utils import timezone
>>> import zoneinfo
@ -460,7 +482,9 @@ values that are returned::
{'day': 16, 'weekday': 3, 'isoweekday': 2, 'hour': 9}
Explicitly passing the timezone to the ``Extract`` function behaves in the same
way, and takes priority over an active timezone::
way, and takes priority over an active timezone:
.. code-block:: pycon
>>> import zoneinfo
>>> melb = zoneinfo.ZoneInfo('Australia/Melbourne')
@ -482,7 +506,9 @@ way, and takes priority over an active timezone::
Returns the database server's current date and time when the query is executed,
typically using the SQL ``CURRENT_TIMESTAMP``.
Usage example::
Usage example:
.. code-block:: pycon
>>> from django.db.models.functions import Now
>>> Article.objects.filter(published__lte=Now())
@ -558,7 +584,9 @@ The subclasses are all defined as transforms, but they aren't registered with
any fields, because the lookup names are already reserved by the ``Extract``
subclasses.
Usage example::
Usage example:
.. code-block:: pycon
>>> from datetime import datetime
>>> from django.db.models import Count, DateTimeField
@ -610,7 +638,9 @@ with less precision. ``expression`` can have an ``output_field`` of either
``DateField`` or ``DateTimeField``.
Since ``DateField``\s don't have a time component, only ``Trunc`` subclasses
that deal with date-parts can be used with ``DateField``::
that deal with date-parts can be used with ``DateField``:
.. code-block:: pycon
>>> from datetime import datetime, timezone
>>> from django.db.models import Count
@ -684,7 +714,9 @@ truncate all parts of the date up to ``kind`` and allow grouping or filtering
datetimes with less precision. ``expression`` must have an ``output_field`` of
``DateTimeField``.
Usage example::
Usage example:
.. code-block:: pycon
>>> from datetime import date, datetime, timezone
>>> from django.db.models import Count
@ -733,7 +765,9 @@ with less precision. ``expression`` can have an ``output_field`` of either
``TimeField`` or ``DateTimeField``.
Since ``TimeField``\s don't have a date component, only ``Trunc`` subclasses
that deal with time-parts can be used with ``TimeField``::
that deal with time-parts can be used with ``TimeField``:
.. code-block:: pycon
>>> from datetime import datetime, timezone
>>> from django.db.models import Count, TimeField
@ -782,7 +816,9 @@ We'll be using the following model in math function examples::
Returns the absolute value of a numeric field or expression.
Usage example::
Usage example:
.. code-block:: pycon
>>> from django.db.models.functions import Abs
>>> Vector.objects.create(x=-0.5, y=1.1)
@ -790,7 +826,9 @@ Usage example::
>>> vector.x_abs, vector.y_abs
(0.5, 1.1)
It can also be registered as a transform. For example::
It can also be registered as a transform. For example:
.. code-block:: pycon
>>> from django.db.models import FloatField
>>> from django.db.models.functions import Abs
@ -806,7 +844,9 @@ It can also be registered as a transform. For example::
Returns the arccosine of a numeric field or expression. The expression value
must be within the range -1 to 1.
Usage example::
Usage example:
.. code-block:: pycon
>>> from django.db.models.functions import ACos
>>> Vector.objects.create(x=0.5, y=-0.9)
@ -814,7 +854,9 @@ Usage example::
>>> vector.x_acos, vector.y_acos
(1.0471975511965979, 2.6905658417935308)
It can also be registered as a transform. For example::
It can also be registered as a transform. For example:
.. code-block:: pycon
>>> from django.db.models import FloatField
>>> from django.db.models.functions import ACos
@ -830,7 +872,9 @@ It can also be registered as a transform. For example::
Returns the arcsine of a numeric field or expression. The expression value must
be in the range -1 to 1.
Usage example::
Usage example:
.. code-block:: pycon
>>> from django.db.models.functions import ASin
>>> Vector.objects.create(x=0, y=1)
@ -838,7 +882,9 @@ Usage example::
>>> vector.x_asin, vector.y_asin
(0.0, 1.5707963267948966)
It can also be registered as a transform. For example::
It can also be registered as a transform. For example:
.. code-block:: pycon
>>> from django.db.models import FloatField
>>> from django.db.models.functions import ASin
@ -853,7 +899,9 @@ It can also be registered as a transform. For example::
Returns the arctangent of a numeric field or expression.
Usage example::
Usage example:
.. code-block:: pycon
>>> from django.db.models.functions import ATan
>>> Vector.objects.create(x=3.12, y=6.987)
@ -861,7 +909,9 @@ Usage example::
>>> vector.x_atan, vector.y_atan
(1.2606282660069106, 1.428638798133829)
It can also be registered as a transform. For example::
It can also be registered as a transform. For example:
.. code-block:: pycon
>>> from django.db.models import FloatField
>>> from django.db.models.functions import ATan
@ -876,7 +926,9 @@ It can also be registered as a transform. For example::
Returns the arctangent of ``expression1 / expression2``.
Usage example::
Usage example:
.. code-block:: pycon
>>> from django.db.models.functions import ATan2
>>> Vector.objects.create(x=2.5, y=1.9)
@ -892,7 +944,9 @@ Usage example::
Returns the smallest integer greater than or equal to a numeric field or
expression.
Usage example::
Usage example:
.. code-block:: pycon
>>> from django.db.models.functions import Ceil
>>> Vector.objects.create(x=3.12, y=7.0)
@ -900,7 +954,9 @@ Usage example::
>>> vector.x_ceil, vector.y_ceil
(4.0, 7.0)
It can also be registered as a transform. For example::
It can also be registered as a transform. For example:
.. code-block:: pycon
>>> from django.db.models import FloatField
>>> from django.db.models.functions import Ceil
@ -915,7 +971,9 @@ It can also be registered as a transform. For example::
Returns the cosine of a numeric field or expression.
Usage example::
Usage example:
.. code-block:: pycon
>>> from django.db.models.functions import Cos
>>> Vector.objects.create(x=-8.0, y=3.1415926)
@ -923,7 +981,9 @@ Usage example::
>>> vector.x_cos, vector.y_cos
(-0.14550003380861354, -0.9999999999999986)
It can also be registered as a transform. For example::
It can also be registered as a transform. For example:
.. code-block:: pycon
>>> from django.db.models import FloatField
>>> from django.db.models.functions import Cos
@ -938,7 +998,9 @@ It can also be registered as a transform. For example::
Returns the cotangent of a numeric field or expression.
Usage example::
Usage example:
.. code-block:: pycon
>>> from django.db.models.functions import Cot
>>> Vector.objects.create(x=12.0, y=1.0)
@ -946,7 +1008,9 @@ Usage example::
>>> vector.x_cot, vector.y_cot
(-1.5726734063976826, 0.642092615934331)
It can also be registered as a transform. For example::
It can also be registered as a transform. For example:
.. code-block:: pycon
>>> from django.db.models import FloatField
>>> from django.db.models.functions import Cot
@ -961,7 +1025,9 @@ It can also be registered as a transform. For example::
Converts a numeric field or expression from radians to degrees.
Usage example::
Usage example:
.. code-block:: pycon
>>> from django.db.models.functions import Degrees
>>> Vector.objects.create(x=-1.57, y=3.14)
@ -969,7 +1035,9 @@ Usage example::
>>> vector.x_d, vector.y_d
(-89.95437383553924, 179.9087476710785)
It can also be registered as a transform. For example::
It can also be registered as a transform. For example:
.. code-block:: pycon
>>> from django.db.models import FloatField
>>> from django.db.models.functions import Degrees
@ -985,7 +1053,9 @@ It can also be registered as a transform. For example::
Returns the value of ``e`` (the natural logarithm base) raised to the power of
a numeric field or expression.
Usage example::
Usage example:
.. code-block:: pycon
>>> from django.db.models.functions import Exp
>>> Vector.objects.create(x=5.4, y=-2.0)
@ -993,7 +1063,9 @@ Usage example::
>>> vector.x_exp, vector.y_exp
(221.40641620418717, 0.1353352832366127)
It can also be registered as a transform. For example::
It can also be registered as a transform. For example:
.. code-block:: pycon
>>> from django.db.models import FloatField
>>> from django.db.models.functions import Exp
@ -1009,7 +1081,9 @@ It can also be registered as a transform. For example::
Returns the largest integer value not greater than a numeric field or
expression.
Usage example::
Usage example:
.. code-block:: pycon
>>> from django.db.models.functions import Floor
>>> Vector.objects.create(x=5.4, y=-2.3)
@ -1017,7 +1091,9 @@ Usage example::
>>> vector.x_floor, vector.y_floor
(5.0, -3.0)
It can also be registered as a transform. For example::
It can also be registered as a transform. For example:
.. code-block:: pycon
>>> from django.db.models import FloatField
>>> from django.db.models.functions import Floor
@ -1032,7 +1108,9 @@ It can also be registered as a transform. For example::
Returns the natural logarithm a numeric field or expression.
Usage example::
Usage example:
.. code-block:: pycon
>>> from django.db.models.functions import Ln
>>> Vector.objects.create(x=5.4, y=233.0)
@ -1040,7 +1118,9 @@ Usage example::
>>> vector.x_ln, vector.y_ln
(1.6863989535702288, 5.4510384535657)
It can also be registered as a transform. For example::
It can also be registered as a transform. For example:
.. code-block:: pycon
>>> from django.db.models import FloatField
>>> from django.db.models.functions import Ln
@ -1056,7 +1136,9 @@ It can also be registered as a transform. For example::
Accepts two numeric fields or expressions and returns the logarithm of
the first to base of the second.
Usage example::
Usage example:
.. code-block:: pycon
>>> from django.db.models.functions import Log
>>> Vector.objects.create(x=2.0, y=4.0)
@ -1072,7 +1154,9 @@ Usage example::
Accepts two numeric fields or expressions and returns the remainder of
the first divided by the second (modulo operation).
Usage example::
Usage example:
.. code-block:: pycon
>>> from django.db.models.functions import Mod
>>> Vector.objects.create(x=5.4, y=2.3)
@ -1095,7 +1179,9 @@ Returns the value of the mathematical constant ``π``.
Accepts two numeric fields or expressions and returns the value of the first
raised to the power of the second.
Usage example::
Usage example:
.. code-block:: pycon
>>> from django.db.models.functions import Power
>>> Vector.objects.create(x=2, y=-2)
@ -1110,7 +1196,9 @@ Usage example::
Converts a numeric field or expression from degrees to radians.
Usage example::
Usage example:
.. code-block:: pycon
>>> from django.db.models.functions import Radians
>>> Vector.objects.create(x=-90, y=180)
@ -1118,7 +1206,9 @@ Usage example::
>>> vector.x_r, vector.y_r
(-1.5707963267948966, 3.141592653589793)
It can also be registered as a transform. For example::
It can also be registered as a transform. For example:
.. code-block:: pycon
>>> from django.db.models import FloatField
>>> from django.db.models.functions import Radians
@ -1142,7 +1232,9 @@ Rounds a numeric field or expression to ``precision`` (must be an integer)
decimal places. By default, it rounds to the nearest integer. Whether half
values are rounded up or down depends on the database.
Usage example::
Usage example:
.. code-block:: pycon
>>> from django.db.models.functions import Round
>>> Vector.objects.create(x=5.4, y=-2.37)
@ -1150,7 +1242,9 @@ Usage example::
>>> vector.x_r, vector.y_r
(5.0, -2.4)
It can also be registered as a transform. For example::
It can also be registered as a transform. For example:
.. code-block:: pycon
>>> from django.db.models import FloatField
>>> from django.db.models.functions import Round
@ -1165,7 +1259,9 @@ It can also be registered as a transform. For example::
Returns the sign (-1, 0, 1) of a numeric field or expression.
Usage example::
Usage example:
.. code-block:: pycon
>>> from django.db.models.functions import Sign
>>> Vector.objects.create(x=5.4, y=-2.3)
@ -1173,7 +1269,9 @@ Usage example::
>>> vector.x_sign, vector.y_sign
(1, -1)
It can also be registered as a transform. For example::
It can also be registered as a transform. For example:
.. code-block:: pycon
>>> from django.db.models import FloatField
>>> from django.db.models.functions import Sign
@ -1188,7 +1286,9 @@ It can also be registered as a transform. For example::
Returns the sine of a numeric field or expression.
Usage example::
Usage example:
.. code-block:: pycon
>>> from django.db.models.functions import Sin
>>> Vector.objects.create(x=5.4, y=-2.3)
@ -1196,7 +1296,9 @@ Usage example::
>>> vector.x_sin, vector.y_sin
(-0.7727644875559871, -0.7457052121767203)
It can also be registered as a transform. For example::
It can also be registered as a transform. For example:
.. code-block:: pycon
>>> from django.db.models import FloatField
>>> from django.db.models.functions import Sin
@ -1211,7 +1313,9 @@ It can also be registered as a transform. For example::
Returns the square root of a nonnegative numeric field or expression.
Usage example::
Usage example:
.. code-block:: pycon
>>> from django.db.models.functions import Sqrt
>>> Vector.objects.create(x=4.0, y=12.0)
@ -1219,7 +1323,9 @@ Usage example::
>>> vector.x_sqrt, vector.y_sqrt
(2.0, 3.46410)
It can also be registered as a transform. For example::
It can also be registered as a transform. For example:
.. code-block:: pycon
>>> from django.db.models import FloatField
>>> from django.db.models.functions import Sqrt
@ -1234,7 +1340,9 @@ It can also be registered as a transform. For example::
Returns the tangent of a numeric field or expression.
Usage example::
Usage example:
.. code-block:: pycon
>>> from django.db.models.functions import Tan
>>> Vector.objects.create(x=0, y=12)
@ -1242,7 +1350,9 @@ Usage example::
>>> vector.x_tan, vector.y_tan
(0.0, -0.6358599286615808)
It can also be registered as a transform. For example::
It can also be registered as a transform. For example:
.. code-block:: pycon
>>> from django.db.models import FloatField
>>> from django.db.models.functions import Tan
@ -1267,7 +1377,9 @@ function.
Like :class:`Length`, it can be registered as a transform on ``IntegerField``.
The default lookup name is ``chr``.
Usage example::
Usage example:
.. code-block:: pycon
>>> from django.db.models.functions import Chr
>>> Author.objects.create(name='Margaret Smith')
@ -1291,7 +1403,9 @@ This function will never have a null result. On backends where a null argument
results in the entire expression being null, Django will ensure that each null
part is converted to an empty string first.
Usage example::
Usage example:
.. code-block:: pycon
>>> # Get the display name as "name (goes_by)"
>>> from django.db.models import CharField, Value as V
@ -1313,7 +1427,9 @@ Usage example::
Returns the first ``length`` characters of the given text field or expression.
Usage example::
Usage example:
.. code-block:: pycon
>>> from django.db.models.functions import Left
>>> Author.objects.create(name='Margaret Smith')
@ -1329,7 +1445,9 @@ Usage example::
Accepts a single text field or expression and returns the number of characters
the value has. If the expression is null, then the length will also be null.
Usage example::
Usage example:
.. code-block:: pycon
>>> # Get the length of the name and goes_by fields
>>> from django.db.models.functions import Length
@ -1340,7 +1458,9 @@ Usage example::
>>> print(author.name_length, author.goes_by_length)
(14, None)
It can also be registered as a transform. For example::
It can also be registered as a transform. For example:
.. code-block:: pycon
>>> from django.db.models import CharField
>>> from django.db.models.functions import Length
@ -1358,7 +1478,9 @@ representation.
It can also be registered as a transform as described in :class:`Length`.
Usage example::
Usage example:
.. code-block:: pycon
>>> from django.db.models.functions import Lower
>>> Author.objects.create(name='Margaret Smith')
@ -1375,7 +1497,9 @@ Returns the value of the given text field or expression padded on the left side
with ``fill_text`` so that the resulting value is ``length`` characters long.
The default ``fill_text`` is a space.
Usage example::
Usage example:
.. code-block:: pycon
>>> from django.db.models import Value
>>> from django.db.models.functions import LPad
@ -1403,7 +1527,9 @@ string.
It can also be registered as a transform as described in :class:`Length`.
Usage example::
Usage example:
.. code-block:: pycon
>>> from django.db.models.functions import MD5
>>> Author.objects.create(name='Margaret Smith')
@ -1424,7 +1550,9 @@ than one character long.
It can also be registered as a transform as described in :class:`Length`.
The default lookup name is ``ord``.
Usage example::
Usage example:
.. code-block:: pycon
>>> from django.db.models.functions import Ord
>>> Author.objects.create(name='Margaret Smith')
@ -1440,7 +1568,9 @@ Usage example::
Returns the value of the given text field or expression repeated ``number``
times.
Usage example::
Usage example:
.. code-block:: pycon
>>> from django.db.models.functions import Repeat
>>> Author.objects.create(name='John', alias='j')
@ -1458,7 +1588,9 @@ Replaces all occurrences of ``text`` with ``replacement`` in ``expression``.
The default replacement text is the empty string. The arguments to the function
are case-sensitive.
Usage example::
Usage example:
.. code-block:: pycon
>>> from django.db.models import Value
>>> from django.db.models.functions import Replace
@ -1480,7 +1612,9 @@ expression in reverse order.
It can also be registered as a transform as described in :class:`Length`. The
default lookup name is ``reverse``.
Usage example::
Usage example:
.. code-block:: pycon
>>> from django.db.models.functions import Reverse
>>> Author.objects.create(name='Margaret Smith')
@ -1495,7 +1629,9 @@ Usage example::
Returns the last ``length`` characters of the given text field or expression.
Usage example::
Usage example:
.. code-block:: pycon
>>> from django.db.models.functions import Right
>>> Author.objects.create(name='Margaret Smith')
@ -1533,7 +1669,9 @@ the string.
They can also be registered as transforms as described in :class:`Length`.
Usage example::
Usage example:
.. code-block:: pycon
>>> from django.db.models.functions import SHA1
>>> Author.objects.create(name='Margaret Smith')
@ -1561,7 +1699,9 @@ Returns a positive integer corresponding to the 1-indexed position of the first
occurrence of ``substring`` inside ``string``, or 0 if ``substring`` is not
found.
Usage example::
Usage example:
.. code-block:: pycon
>>> from django.db.models import Value as V
>>> from django.db.models.functions import StrIndex
@ -1593,7 +1733,9 @@ Returns a substring of length ``length`` from the field or expression starting
at position ``pos``. The position is 1-indexed, so the position must be greater
than 0. If ``length`` is ``None``, then the rest of the string will be returned.
Usage example::
Usage example:
.. code-block:: pycon
>>> # Set the alias to the first 5 characters of the name as lowercase
>>> from django.db.models.functions import Lower, Substr
@ -1611,7 +1753,9 @@ Usage example::
Returns the value of the given text field or expression with leading and
trailing spaces removed.
Usage example::
Usage example:
.. code-block:: pycon
>>> from django.db.models.functions import Trim
>>> Author.objects.create(name=' John ', alias='j')
@ -1630,7 +1774,9 @@ representation.
It can also be registered as a transform as described in :class:`Length`.
Usage example::
Usage example:
.. code-block:: pycon
>>> from django.db.models.functions import Upper
>>> Author.objects.create(name='Margaret Smith')

View File

@ -232,7 +232,9 @@ directly support ``output_field`` you will need to wrap the expression with
F('active_at') + F('duration'), output_field=DateTimeField()))
When referencing relational fields such as ``ForeignKey``, ``F()`` returns the
primary key value rather than a model instance::
primary key value rather than a model instance:
.. code-block:: pycon
>> car = Company.objects.annotate(built_by=F('manufacturer'))[0]
>> car.manufacturer
@ -547,7 +549,9 @@ You can add an explicit subquery to a ``QuerySet`` using the ``Subquery``
expression.
For example, to annotate each post with the email address of the author of the
newest comment on that post::
newest comment on that post:
.. code-block:: pycon
>>> from django.db.models import OuterRef, Subquery
>>> newest = Comment.objects.filter(post=OuterRef('pk')).order_by('-created_at')
@ -584,7 +588,9 @@ outer queryset is resolved.
Instances of ``OuterRef`` may be used in conjunction with nested instances
of ``Subquery`` to refer to a containing queryset that isn't the immediate
parent. For example, this queryset would need to be within a nested pair of
``Subquery`` instances to resolve correctly::
``Subquery`` instances to resolve correctly:
.. code-block:: pycon
>>> Book.objects.filter(author=OuterRef(OuterRef('pk')))
@ -593,7 +599,9 @@ Limiting a subquery to a single column
There are times when a single column must be returned from a ``Subquery``, for
instance, to use a ``Subquery`` as the target of an ``__in`` lookup. To return
all comments for posts published within the last day::
all comments for posts published within the last day:
.. code-block:: pycon
>>> from datetime import timedelta
>>> from django.utils import timezone
@ -608,7 +616,9 @@ Limiting the subquery to a single row
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
To prevent a subquery from returning multiple rows, a slice (``[:1]``) of the
queryset is used::
queryset is used:
.. code-block:: pycon
>>> subquery = Subquery(newest.values('email')[:1])
>>> Post.objects.annotate(newest_commenter_email=subquery)
@ -630,7 +640,9 @@ many cases it will perform better than a subquery since the database is able to
stop evaluation of the subquery when a first matching row is found.
For example, to annotate each post with whether or not it has a comment from
within the last day::
within the last day:
.. code-block:: pycon
>>> from django.db.models import Exists, OuterRef
>>> from datetime import timedelta
@ -668,7 +680,9 @@ Filtering on a ``Subquery()`` or ``Exists()`` expressions
``Subquery()`` that returns a boolean value and ``Exists()`` may be used as a
``condition`` in :class:`~django.db.models.expressions.When` expressions, or to
directly filter a queryset::
directly filter a queryset:
.. code-block:: pycon
>>> recent_comments = Comment.objects.filter(...) # From above
>>> Post.objects.filter(Exists(recent_comments))
@ -684,7 +698,9 @@ combination of :meth:`~.QuerySet.filter`, :meth:`~.QuerySet.values`, and
:meth:`~.QuerySet.annotate` to get the subquery grouping correct.
Assuming both models have a ``length`` field, to find posts where the post
length is greater than the total length of all combined comments::
length is greater than the total length of all combined comments:
.. code-block:: pycon
>>> from django.db.models import OuterRef, Subquery, Sum
>>> comments = Comment.objects.filter(post=OuterRef('pk')).order_by().values('post')
@ -710,7 +726,9 @@ Raw SQL expressions
.. class:: RawSQL(sql, params, output_field=None)
Sometimes database expressions can't easily express a complex ``WHERE`` clause.
In these edge cases, use the ``RawSQL`` expression. For example::
In these edge cases, use the ``RawSQL`` expression. For example:
.. code-block:: pycon
>>> from django.db.models.expressions import RawSQL
>>> queryset.annotate(val=RawSQL("select col from sometable where othercol = %s", (param,)))
@ -719,7 +737,9 @@ These extra lookups may not be portable to different database engines (because
you're explicitly writing SQL code) and violate the DRY principle, so you
should avoid them if possible.
``RawSQL`` expressions can also be used as the target of ``__in`` filters::
``RawSQL`` expressions can also be used as the target of ``__in`` filters:
.. code-block:: pycon
>>> queryset.filter(id__in=RawSQL("select id from sometable where col = %s", (param,)))
@ -732,7 +752,9 @@ should avoid them if possible.
your SQL with user-provided data.
You also must not quote placeholders in the SQL string. This example is
vulnerable to SQL injection because of the quotes around ``%s``::
vulnerable to SQL injection because of the quotes around ``%s``:
.. code-block:: pycon
RawSQL("select col from sometable where othercol = '%s'") # unsafe!
@ -785,7 +807,9 @@ The ``frame`` parameter specifies which other rows that should be used in the
computation. See :ref:`window-frames` for details.
For example, to annotate each movie with the average rating for the movies by
the same studio in the same genre and release year::
the same studio in the same genre and release year:
.. code-block:: pycon
>>> from django.db.models import Avg, F, Window
>>> Movie.objects.annotate(
@ -803,7 +827,9 @@ same partition and frame. For example, you could modify the previous example
to also include the best and worst rating in each movie's group (same studio,
genre, and release year) by using three window functions in the same query. The
partition and ordering from the previous example is extracted into a dictionary
to reduce repetition::
to reduce repetition:
.. code-block:: pycon
>>> from django.db.models import Avg, F, Max, Min, Window
>>> window = {
@ -829,7 +855,9 @@ performing aggregation.
For example, a query that relies on aggregation and has an ``OR``-ed filter
against a window function and a field is not supported. Applying combined
predicates post-aggregation could cause rows that would normally be excluded
from groups to be included::
from groups to be included:
.. code-block:: pycon
>>> qs = Movie.objects.annotate(
>>> category_rank=Window(
@ -878,7 +906,9 @@ ordinary sequence of rows.
This attribute is set to ``'ROWS'``.
Both classes return SQL with the template::
Both classes return SQL with the template:
.. code-block:: sql
%(frame_type)s BETWEEN %(start)s AND %(end)s
@ -909,7 +939,9 @@ includes both the ``start`` and ``end`` points, this may be expressed with::
If a movie's "peers" are described as movies released by the same studio in the
same genre in the same year, this ``RowRange`` example annotates each movie
with the average rating of a movie's two prior and two following peers::
with the average rating of a movie's two prior and two following peers:
.. code-block:: pycon
>>> from django.db.models import Avg, F, RowRange, Window
>>> Movie.objects.annotate(
@ -925,7 +957,9 @@ If the database supports it, you can specify the start and end points based on
values of an expression in the partition. If the ``released`` field of the
``Movie`` model stores the release month of each movies, this ``ValueRange``
example annotates each movie with the average rating of a movie's peers
released between twelve months before and twelve months after the each movie::
released between twelve months before and twelve months after the each movie:
.. code-block:: pycon
>>> from django.db.models import Avg, F, ValueRange, Window
>>> Movie.objects.annotate(
@ -1012,7 +1046,9 @@ calling the appropriate methods on the wrapped expression.
.. method:: get_source_expressions()
Returns an ordered list of inner expressions. For example::
Returns an ordered list of inner expressions. For example:
.. code-block:: pycon
>>> Sum(F('foo')).get_source_expressions()
[F('foo')]
@ -1170,7 +1206,9 @@ to play nice with other query expressions::
def set_source_expressions(self, expressions):
self.expressions = expressions
Let's see how it works::
Let's see how it works:
.. code-block:: pycon
>>> from django.db.models import F, Value, CharField
>>> qs = Company.objects.annotate(

View File

@ -249,7 +249,9 @@ the ``.name`` and ``.value`` properties on the members.
If you don't need to have the human-readable names translated, you can have
them inferred from the member name (replacing underscores with spaces and using
title-case)::
title-case):
.. code-block:: pycon
>>> class Vehicle(models.TextChoices):
... CAR = 'C'
@ -274,7 +276,9 @@ Django provides an ``IntegerChoices`` class. For example::
It is also possible to make use of the `Enum Functional API
<https://docs.python.org/3/library/enum.html#functional-api>`_ with the caveat
that labels are automatically generated as highlighted above::
that labels are automatically generated as highlighted above:
.. code-block:: pycon
>>> MedalType = models.TextChoices('MedalType', 'GOLD SILVER BRONZE')
>>> MedalType.choices
@ -1597,7 +1601,9 @@ The possible values for :attr:`~ForeignKey.on_delete` are found in
``Artist`` can be deleted even if that implies deleting an ``Album``
which is referenced by a ``Song``, because ``Song`` also references
``Artist`` itself through a cascading relationship. For example::
``Artist`` itself through a cascading relationship. For example:
.. code-block:: pycon
>>> artist_one = Artist.objects.create(name='artist one')
>>> artist_two = Artist.objects.create(name='artist two')
@ -2025,7 +2031,9 @@ With the following example::
related_name='supervisor_of',
)
your resulting ``User`` model will have the following attributes::
your resulting ``User`` model will have the following attributes:
.. code-block:: pycon
>>> user = User.objects.get(pk=1)
>>> hasattr(user, 'myspecialuser')

View File

@ -125,7 +125,9 @@ Refreshing objects from database
================================
If you delete a field from a model instance, accessing it again reloads the
value from the database::
value from the database:
.. code-block:: pycon
>>> obj = MyModel.objects.first()
>>> del obj.field
@ -415,7 +417,9 @@ Auto-incrementing primary keys
If a model has an :class:`~django.db.models.AutoField` — an auto-incrementing
primary key — then that auto-incremented value will be calculated and saved as
an attribute on your object the first time you call ``save()``::
an attribute on your object the first time you call ``save()``:
.. code-block:: pycon
>>> b2 = Blog(name='Cheddar Talk', tagline='Thoughts on cheese.')
>>> b2.id # Returns None, because b2 doesn't have an ID yet.
@ -447,7 +451,9 @@ Explicitly specifying auto-primary-key values
If a model has an :class:`~django.db.models.AutoField` but you want to define a
new object's ID explicitly when saving, define it explicitly before saving,
rather than relying on the auto-assignment of the ID::
rather than relying on the auto-assignment of the ID:
.. code-block:: pycon
>>> b3 = Blog(id=3, name='Cheddar Talk', tagline='Thoughts on cheese.')
>>> b3.id # Returns 3.
@ -573,7 +579,9 @@ Updating attributes based on existing fields
Sometimes you'll need to perform a simple arithmetic task on a field, such
as incrementing or decrementing the current value. One way of achieving this is
doing the arithmetic in Python like::
doing the arithmetic in Python like:
.. code-block:: pycon
>>> product = Product.objects.get(name='Venezuelan Beaver Cheese')
>>> product.number_sold += 1
@ -588,7 +596,9 @@ the update relative to the original field value, rather than as an explicit
assignment of a new value. Django provides :class:`F expressions
<django.db.models.F>` for performing this kind of relative update. Using
:class:`F expressions <django.db.models.F>`, the previous example is expressed
as::
as:
.. code-block:: pycon
>>> from django.db.models import F
>>> product = Product.objects.get(name='Venezuelan Beaver Cheese')
@ -862,7 +872,7 @@ For example::
name = models.CharField(max_length=60)
shirt_size = models.CharField(max_length=2, choices=SHIRT_SIZES)
::
.. code-block:: pycon
>>> p = Person(name="Fred Flintstone", shirt_size="L")
>>> p.save()

View File

@ -234,20 +234,26 @@ not be looking at your Django code. For example::
and ``set_RELATED_order()``, where ``RELATED`` is the lowercased model name. For
example, assuming that a ``Question`` object has multiple related ``Answer``
objects, the list returned contains the primary keys of the related ``Answer``
objects::
objects:
.. code-block:: pycon
>>> question = Question.objects.get(id=1)
>>> question.get_answer_order()
[1, 2, 3]
The order of a ``Question`` object's related ``Answer`` objects can be set by
passing in a list of ``Answer`` primary keys::
passing in a list of ``Answer`` primary keys:
.. code-block:: pycon
>>> question.set_answer_order([3, 1, 2])
The related objects also get two methods, ``get_next_in_order()`` and
``get_previous_in_order()``, which can be used to access those objects in their
proper order. Assuming the ``Answer`` objects are ordered by ``id``::
proper order. Assuming the ``Answer`` objects are ordered by ``id``:
.. code-block:: pycon
>>> answer = Answer.objects.get(id=2)
>>> answer.get_next_in_order()

View File

@ -103,7 +103,9 @@ than the results that are currently in the database.
If you only want to pickle the necessary information to recreate the
``QuerySet`` from the database at a later time, pickle the ``query`` attribute
of the ``QuerySet``. You can then recreate the original ``QuerySet`` (without
any results loaded) using some code like this::
any results loaded) using some code like this:
.. code-block:: pycon
>>> import pickle
>>> query = pickle.loads(s) # Assuming 's' is the pickled string.
@ -118,7 +120,9 @@ described here.
.. admonition:: Restrictions on ``QuerySet.values_list()``
If you recreate :meth:`QuerySet.values_list` using the pickled ``query``
attribute, it will be converted to :meth:`QuerySet.values`::
attribute, it will be converted to :meth:`QuerySet.values`:
.. code-block:: pycon
>>> import pickle
>>> qs = Blog.objects.values_list('id', 'name')
@ -273,7 +277,9 @@ that reference a single field can be anonymous arguments. Everything
else must be a keyword argument.
For example, if you were manipulating a list of blogs, you may want
to determine how many entries have been made in each blog::
to determine how many entries have been made in each blog:
.. code-block:: pycon
>>> from django.db.models import Count
>>> q = Blog.objects.annotate(Count('entry'))
@ -286,7 +292,9 @@ to determine how many entries have been made in each blog::
The ``Blog`` model doesn't define an ``entry__count`` attribute by itself,
but by using a keyword argument to specify the aggregate function, you can
control the name of the annotation::
control the name of the annotation:
.. code-block:: pycon
>>> q = Blog.objects.annotate(number_of_entries=Count('entry'))
# The number of entries on the first blog, using the name provided
@ -309,7 +317,9 @@ Not selecting the unused value removes redundant work from the database which
should result in better performance.
For example, if you want to find blogs with more than 5 entries, but are not
interested in the exact number of entries, you could do this::
interested in the exact number of entries, you could do this:
.. code-block:: pycon
>>> from django.db.models import Count
>>> blogs = Blog.objects.alias(entries=Count('entry')).filter(entries__gt=5)
@ -528,7 +538,9 @@ field names, the database will only compare the specified field names.
value in column ``a``. If you don't specify an order, you'll get some
arbitrary row.
Examples (those after the first will only work on PostgreSQL)::
Examples (those after the first will only work on PostgreSQL):
.. code-block:: pycon
>>> Author.objects.distinct()
[...]
@ -575,7 +587,9 @@ Each of those dictionaries represents an object, with the keys corresponding to
the attribute names of model objects.
This example compares the dictionaries of ``values()`` with the normal model
objects::
objects:
.. code-block:: pycon
# This list contains a Blog object.
>>> Blog.objects.filter(name__startswith='Beatles')
@ -591,7 +605,9 @@ the fields, each dictionary will contain only the field keys/values for the
fields you specify. If you don't specify the fields, each dictionary will
contain a key and value for every field in the database table.
Example::
Example:
.. code-block:: pycon
>>> Blog.objects.values()
<QuerySet [{'id': 1, 'name': 'Beatles Blog', 'tagline': 'All the latest Beatles news.'}]>
@ -599,14 +615,18 @@ Example::
<QuerySet [{'id': 1, 'name': 'Beatles Blog'}]>
The ``values()`` method also takes optional keyword arguments,
``**expressions``, which are passed through to :meth:`annotate`::
``**expressions``, which are passed through to :meth:`annotate`:
.. code-block:: pycon
>>> from django.db.models.functions import Lower
>>> Blog.objects.values(lower_name=Lower('name'))
<QuerySet [{'lower_name': 'beatles blog'}]>
You can use built-in and :doc:`custom lookups </howto/custom-lookups>` in
ordering. For example::
ordering. For example:
.. code-block:: pycon
>>> from django.db.models import CharField
>>> from django.db.models.functions import Lower
@ -616,7 +636,9 @@ ordering. For example::
An aggregate within a ``values()`` clause is applied before other arguments
within the same ``values()`` clause. If you need to group by another value,
add it to an earlier ``values()`` clause instead. For example::
add it to an earlier ``values()`` clause instead. For example:
.. code-block:: pycon
>>> from django.db.models import Count
>>> Blog.objects.values('entry__authors', entries=Count('entry'))
@ -635,7 +657,9 @@ A few subtleties that are worth mentioning:
or ``foo_id`` and you will get back the same thing (the dictionary key
will match the field name you passed in).
For example::
For example:
.. code-block:: pycon
>>> Entry.objects.values()
<QuerySet [{'blog_id': 1, 'headline': 'First Entry', ...}, ...]>
@ -662,7 +686,9 @@ A few subtleties that are worth mentioning:
* Combining transforms and aggregates requires the use of two :meth:`annotate`
calls, either explicitly or as keyword arguments to :meth:`values`. As above,
if the transform has been registered on the relevant field type the first
:meth:`annotate` can be omitted, thus the following examples are equivalent::
:meth:`annotate` can be omitted, thus the following examples are equivalent:
.. code-block:: pycon
>>> from django.db.models import CharField, Count
>>> from django.db.models.functions import Lower
@ -694,7 +720,9 @@ but it doesn't really matter. This is your chance to really flaunt your
individualism.
You can also refer to fields on related models with reverse relations through
``OneToOneField``, ``ForeignKey`` and ``ManyToManyField`` attributes::
``OneToOneField``, ``ForeignKey`` and ``ManyToManyField`` attributes:
.. code-block:: pycon
>>> Blog.objects.values('name', 'entry__headline')
<QuerySet [{'name': 'My blog', 'entry__headline': 'An entry'},
@ -724,7 +752,9 @@ You can also refer to fields on related models with reverse relations through
This is similar to ``values()`` except that instead of returning dictionaries,
it returns tuples when iterated over. Each tuple contains the value from the
respective field or expression passed into the ``values_list()`` call — so the
first item is the first field, etc. For example::
first item is the first field, etc. For example:
.. code-block:: pycon
>>> Entry.objects.values_list('id', 'headline')
<QuerySet [(1, 'First entry'), ...]>
@ -734,7 +764,9 @@ first item is the first field, etc. For example::
If you only pass in a single field, you can also pass in the ``flat``
parameter. If ``True``, this will mean the returned results are single values,
rather than one-tuples. An example should make the difference clearer::
rather than one-tuples. An example should make the difference clearer:
.. code-block:: pycon
>>> Entry.objects.values_list('id').order_by('id')
<QuerySet[(1,), (2,), (3,), ...]>
@ -745,7 +777,9 @@ rather than one-tuples. An example should make the difference clearer::
It is an error to pass in ``flat`` when there is more than one field.
You can pass ``named=True`` to get results as a
:func:`~python:collections.namedtuple`::
:func:`~python:collections.namedtuple`:
.. code-block:: pycon
>>> Entry.objects.values_list('id', 'headline', named=True)
<QuerySet [Row(id=1, headline='First entry'), ...]>
@ -757,7 +791,9 @@ If you don't pass any values to ``values_list()``, it will return all the
fields in the model, in the order they were declared.
A common need is to get a specific field value of a certain model instance. To
achieve that, use ``values_list()`` followed by a ``get()`` call::
achieve that, use ``values_list()`` followed by a ``get()`` call:
.. code-block:: pycon
>>> Entry.objects.values_list('headline', flat=True).get(pk=1)
'First entry'
@ -769,7 +805,9 @@ other multivalued relations (such as the one-to-many relation of a reverse
foreign key) because the "one row, one object" assumption doesn't hold.
For example, notice the behavior when querying across a
:class:`~django.db.models.ManyToManyField`::
:class:`~django.db.models.ManyToManyField`:
.. code-block:: pycon
>>> Author.objects.values_list('name', 'entry__headline')
<QuerySet [('Noam Chomsky', 'Impressions of Gaza'),
@ -781,7 +819,9 @@ Authors with multiple entries appear multiple times and authors without any
entries have ``None`` for the entry headline.
Similarly, when querying a reverse foreign key, ``None`` appears for entries
not having any author::
not having any author:
.. code-block:: pycon
>>> Entry.objects.values_list('authors')
<QuerySet [('Noam Chomsky',), ('George Orwell',), (None,)]>
@ -819,7 +859,9 @@ given ``type``.
``order``, which defaults to ``'ASC'``, should be either ``'ASC'`` or
``'DESC'``. This specifies how to order the results.
Examples::
Examples:
.. code-block:: pycon
>>> Entry.objects.dates('pub_date', 'year')
[datetime.date(2005, 1, 1)]
@ -887,7 +929,9 @@ Calling ``none()`` will create a queryset that never returns any objects and no
query will be executed when accessing the results. A ``qs.none()`` queryset
is an instance of ``EmptyQuerySet``.
Examples::
Examples:
.. code-block:: pycon
>>> Entry.objects.none()
<QuerySet []>
@ -929,7 +973,9 @@ of other models. Passing different models works as long as the ``SELECT`` list
is the same in all ``QuerySet``\s (at least the types, the names don't matter
as long as the types are in the same order). In such cases, you must use the
column names from the first ``QuerySet`` in ``QuerySet`` methods applied to the
resulting ``QuerySet``. For example::
resulting ``QuerySet``. For example:
.. code-block:: pycon
>>> qs1 = Author.objects.values_list('name')
>>> qs2 = Entry.objects.values_list('headline')
@ -960,7 +1006,9 @@ See :meth:`union` for some restrictions.
.. method:: difference(*other_qs)
Uses SQL's ``EXCEPT`` operator to keep only elements present in the
``QuerySet`` but not in some other ``QuerySet``\s. For example::
``QuerySet`` but not in some other ``QuerySet``\s. For example:
.. code-block:: pycon
>>> qs1.difference(qs2, qs3)
@ -1066,7 +1114,9 @@ specified. This is not recommended in most cases as it is likely to make the
underlying query more complex, and return more data, than is actually needed.
If you need to clear the list of related fields added by past calls of
``select_related`` on a ``QuerySet``, you can pass ``None`` as a parameter::
``select_related`` on a ``QuerySet``, you can pass ``None`` as a parameter:
.. code-block:: pycon
>>> without_relations = queryset.select_related(None)
@ -1121,7 +1171,9 @@ For example, suppose you have these models::
", ".join(topping.name for topping in self.toppings.all()),
)
and run::
and run:
.. code-block:: pycon
>>> Pizza.objects.all()
["Hawaiian (ham, pineapple)", "Seafood (prawns, smoked salmon)"...
@ -1191,12 +1243,16 @@ fields. Suppose we have an additional model to the example above::
The following are all legal:
.. code-block:: pycon
>>> Restaurant.objects.prefetch_related('pizzas__toppings')
This will prefetch all pizzas belonging to restaurants, and all toppings
belonging to those pizzas. This will result in a total of 3 database queries -
one for the restaurants, one for the pizzas, and one for the toppings.
.. code-block:: pycon
>>> Restaurant.objects.prefetch_related('best_pizza__toppings')
This will fetch the best pizza and all the toppings for the best pizza for each
@ -1204,7 +1260,9 @@ restaurant. This will be done in 3 database queries - one for the restaurants,
one for the 'best pizzas', and one for the toppings.
The ``best_pizza`` relationship could also be fetched using ``select_related``
to reduce the query count to 2::
to reduce the query count to 2:
.. code-block:: pycon
>>> Restaurant.objects.select_related('best_pizza').prefetch_related('best_pizza__toppings')
@ -1316,7 +1374,9 @@ where prefetching with a custom ``QuerySet`` is useful:
When using multiple databases, ``Prefetch`` will respect your choice of
database. If the inner query does not specify a database, it will use the
database selected by the outer query. All of the following are valid::
database selected by the outer query. All of the following are valid:
.. code-block:: pycon
>>> # Both inner and outer queries will use the 'replica' database
>>> Restaurant.objects.prefetch_related('pizzas__toppings').using('replica')
@ -1384,14 +1444,18 @@ generated by a ``QuerySet``.
that we can enhance the QuerySet API to allow removing ``extra()``. We are
no longer improving or fixing bugs for this method.
For example, this use of ``extra()``::
For example, this use of ``extra()``:
.. code-block:: pycon
>>> qs.extra(
... select={'val': "select col from sometable where othercol = %s"},
... select_params=(someparam,),
... )
is equivalent to::
is equivalent to:
.. code-block:: pycon
>>> qs.annotate(val=RawSQL("select col from sometable where othercol = %s", (someparam,)))
@ -1758,7 +1822,9 @@ evaluated against if you are using more than one database. The only argument
this method takes is the alias of a database, as defined in
:setting:`DATABASES`.
For example::
For example:
.. code-block:: pycon
# queries the database with the 'default' alias.
>>> Entry.objects.all()
@ -1826,7 +1892,9 @@ lock, that still allows creating rows that merely reference locked rows
PostgreSQL documentation has more details about `row-level lock modes
<https://www.postgresql.org/docs/current/explicit-locking.html#LOCKING-ROWS>`_.
You can't use ``select_for_update()`` on nullable relations::
You can't use ``select_for_update()`` on nullable relations:
.. code-block:: pycon
>>> Person.objects.select_related('hometown').select_for_update()
Traceback (most recent call last):
@ -1834,7 +1902,9 @@ You can't use ``select_for_update()`` on nullable relations::
django.db.utils.NotSupportedError: FOR UPDATE cannot be applied to the nullable side of an outer join
To avoid that restriction, you can exclude null objects if you don't care about
them::
them:
.. code-block:: pycon
>>> Person.objects.select_related('hometown').select_for_update().exclude(hometown=None)
<QuerySet [<Person: ...)>, ...]>
@ -2171,7 +2241,9 @@ whenever a request to a page has a side effect on your data. For more, see
chapters = models.ManyToManyField(Chapter)
You can use ``get_or_create()`` through Book's chapters field, but it only
fetches inside the context of that book::
fetches inside the context of that book:
.. code-block:: pycon
>>> book = Book.objects.create(title="Ulysses")
>>> book.chapters.get_or_create(title="Telemachus")
@ -2256,7 +2328,9 @@ exists in the database, an :exc:`~django.db.IntegrityError` is raised.
This method inserts the provided list of objects into the database in an
efficient manner (generally only 1 query, no matter how many objects there
are), and returns created objects as a list, in the same order as provided::
are), and returns created objects as a list, in the same order as provided:
.. code-block:: pycon
>>> objs = Entry.objects.bulk_create([
... Entry(headline='This is a test'),
@ -2328,7 +2402,9 @@ support it).
This method efficiently updates the given fields on the provided model
instances, generally with one query, and returns the number of objects
updated::
updated:
.. code-block:: pycon
>>> objs = [
... Entry.objects.create(headline='Entry 1'),
@ -2413,7 +2489,9 @@ in the queryset are returned. ``field_name`` must be a unique field or a
distinct field (if there's only one field specified in :meth:`distinct`).
``field_name`` defaults to the primary key.
Example::
Example:
.. code-block:: pycon
>>> Blog.objects.in_bulk([1])
{1: <Blog: Beatles Blog>}
@ -2642,14 +2720,18 @@ aggregated. Complex aggregates cannot use anonymous arguments and must specify
a keyword argument as an alias.
For example, when you are working with blog entries, you may want to know the
number of authors that have contributed blog entries::
number of authors that have contributed blog entries:
.. code-block:: pycon
>>> from django.db.models import Count
>>> q = Blog.objects.aggregate(Count('entry'))
{'entry__count': 16}
By using a keyword argument to specify the aggregate function, you can
control the name of the aggregation value that is returned::
control the name of the aggregation value that is returned:
.. code-block:: pycon
>>> q = Blog.objects.aggregate(number_of_entries=Count('entry'))
{'number_of_entries': 16}
@ -2736,31 +2818,41 @@ the number of rows matched (which may not be equal to the number of rows
updated if some rows already have the new value).
For example, to turn comments off for all blog entries published in 2010,
you could do this::
you could do this:
.. code-block:: pycon
>>> Entry.objects.filter(pub_date__year=2010).update(comments_on=False)
(This assumes your ``Entry`` model has fields ``pub_date`` and ``comments_on``.)
You can update multiple fields — there's no limit on how many. For example,
here we update the ``comments_on`` and ``headline`` fields::
here we update the ``comments_on`` and ``headline`` fields:
.. code-block:: pycon
>>> Entry.objects.filter(pub_date__year=2010).update(comments_on=False, headline='This is old')
The ``update()`` method is applied instantly, and the only restriction on the
:class:`.QuerySet` that is updated is that it can only update columns in the
model's main table, not on related models. You can't do this, for example::
model's main table, not on related models. You can't do this, for example:
.. code-block:: pycon
>>> Entry.objects.update(blog__name='foo') # Won't work!
Filtering based on related fields is still possible, though::
Filtering based on related fields is still possible, though:
.. code-block:: pycon
>>> Entry.objects.filter(blog__id=1).update(comments_on=True)
You cannot call ``update()`` on a :class:`.QuerySet` that has had a slice taken
or can otherwise no longer be filtered.
The ``update()`` method returns the number of affected rows::
The ``update()`` method returns the number of affected rows:
.. code-block:: pycon
>>> Entry.objects.filter(id=64).update(comments_on=True)
1
@ -2830,7 +2922,9 @@ The ``delete()`` is applied instantly. You cannot call ``delete()`` on a
:class:`.QuerySet` that has had a slice taken or can otherwise no longer be
filtered.
For example, to delete all the entries in a particular blog::
For example, to delete all the entries in a particular blog:
.. code-block:: pycon
>>> b = Blog.objects.get(pk=1)
@ -2841,7 +2935,9 @@ For example, to delete all the entries in a particular blog::
By default, Django's :class:`~django.db.models.ForeignKey` emulates the SQL
constraint ``ON DELETE CASCADE`` — in other words, any objects with foreign
keys pointing at the objects to be deleted will be deleted along with them.
For example::
For example:
.. code-block:: pycon
>>> blogs = Blog.objects.all()
@ -2896,7 +2992,9 @@ database would execute the query, including any indexes or joins that would be
used. Knowing these details may help you improve the performance of slow
queries.
For example, when using PostgreSQL::
For example, when using PostgreSQL:
.. code-block:: pycon
>>> print(Blog.objects.filter(title='My Blog').explain())
Seq Scan on blog (cost=0.00..35.50 rows=10 width=12)
@ -2915,7 +3013,9 @@ default, which is usually text-based. PostgreSQL supports ``'TEXT'``,
PostgreSQL's ``'TEXT'`` output and is used by default, if supported.
Some databases accept flags that can return more information about the query.
Pass these flags as keyword arguments. For example, when using PostgreSQL::
Pass these flags as keyword arguments. For example, when using PostgreSQL:
.. code-block:: pycon
>>> print(Blog.objects.filter(title='My Blog').explain(verbose=True, analyze=True))
Seq Scan on public.blog (cost=0.00..35.50 rows=10 width=12) (actual time=0.004..0.004 rows=10 loops=1)
@ -3932,7 +4032,9 @@ in code that receives a list of model instances as opposed to a ``QuerySet``;
for example, when fetching models from a cache or instantiating them manually.
Pass an iterable of model instances (must all be of the same class) and the
lookups or :class:`Prefetch` objects you want to prefetch for. For example::
lookups or :class:`Prefetch` objects you want to prefetch for. For example:
.. code-block:: pycon
>>> from django.db.models import prefetch_related_objects
>>> restaurants = fetch_top_restaurants_from_cache() # A list of Restaurants
@ -3961,7 +4063,9 @@ relationship but on the annotation name (``pizzas_vegetarian`` in example
below).
For example, to find restaurants that have vegetarian pizzas with
``'mozzarella'`` in the name::
``'mozzarella'`` in the name:
.. code-block:: pycon
>>> from django.db.models import FilteredRelation, Q
>>> Restaurant.objects.annotate(
@ -3970,7 +4074,9 @@ For example, to find restaurants that have vegetarian pizzas with
... ),
... ).filter(pizzas_vegetarian__name__icontains='mozzarella')
If there are a large number of pizzas, this queryset performs better than::
If there are a large number of pizzas, this queryset performs better than:
.. code-block:: pycon
>>> Restaurant.objects.filter(
... pizzas__vegetarian=True,

View File

@ -43,7 +43,9 @@ Related objects reference
Adds the specified model objects to the related object set.
Example::
Example:
.. code-block:: pycon
>>> b = Blog.objects.get(id=1)
>>> e = Entry.objects.get(id=234)
@ -88,7 +90,9 @@ Related objects reference
*Asynchronous version*: ``acreate``
Creates a new object, saves it and puts it in the related object set.
Returns the newly created object::
Returns the newly created object:
.. code-block:: pycon
>>> b = Blog.objects.get(id=1)
>>> e = b.entry_set.create(
@ -99,7 +103,9 @@ Related objects reference
# No need to call e.save() at this point -- it's already been saved.
This is equivalent to (but simpler than)::
This is equivalent to (but simpler than):
.. code-block:: pycon
>>> b = Blog.objects.get(id=1)
>>> e = Entry(
@ -125,7 +131,9 @@ Related objects reference
*Asynchronous version*: ``aremove``
Removes the specified model objects from the related object set::
Removes the specified model objects from the related object set:
.. code-block:: pycon
>>> b = Blog.objects.get(id=1)
>>> e = Entry.objects.get(id=234)
@ -172,7 +180,9 @@ Related objects reference
*Asynchronous version*: ``aclear``
Removes all objects from the related object set::
Removes all objects from the related object set:
.. code-block:: pycon
>>> b = Blog.objects.get(id=1)
>>> b.entry_set.clear()
@ -196,7 +206,9 @@ Related objects reference
*Asynchronous version*: ``aset``
Replace the set of related objects::
Replace the set of related objects:
.. code-block:: pycon
>>> new_list = [obj1, obj2, obj3]
>>> e.related_set.set(new_list)

View File

@ -179,7 +179,9 @@ All attributes should be considered read-only, unless stated otherwise.
the request.
The name of each header is stylized with title-casing (e.g. ``User-Agent``)
when it's displayed. You can access headers case-insensitively::
when it's displayed. You can access headers case-insensitively:
.. code-block:: pycon
>>> request.headers
{'User-Agent': 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_6', ...}
@ -200,7 +202,9 @@ All attributes should be considered read-only, unless stated otherwise.
Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_6)
For use in, for example, Django templates, headers can also be looked up
using underscores in place of hyphens::
using underscores in place of hyphens:
.. code-block:: html+django
{{ request.headers.user_agent }}
@ -381,7 +385,9 @@ Methods
attached to the cookie value to ensure the cookie is not older than
``max_age`` seconds.
For example::
For example:
.. code-block:: pycon
>>> request.get_signed_cookie('name')
'Tony'
@ -411,7 +417,9 @@ Methods
.. method:: HttpRequest.accepts(mime_type)
Returns ``True`` if the request ``Accept`` header matches the ``mime_type``
argument::
argument:
.. code-block:: pycon
>>> request.accepts('text/html')
True
@ -492,7 +500,9 @@ a subclass of dictionary. Exceptions are outlined here:
.. classmethod:: QueryDict.fromkeys(iterable, value='', mutable=False, encoding=None)
Creates a new ``QueryDict`` with keys from ``iterable`` and each value
equal to ``value``. For example::
equal to ``value``. For example:
.. code-block:: pycon
>>> QueryDict.fromkeys(['a', 'a', 'b'], value='val')
<QueryDict: {'a': ['val', 'val'], 'b': ['val']}>
@ -530,7 +540,9 @@ a subclass of dictionary. Exceptions are outlined here:
Takes either a ``QueryDict`` or a dictionary. Like :meth:`dict.update`,
except it *appends* to the current dictionary items rather than replacing
them. For example::
them. For example:
.. code-block:: pycon
>>> q = QueryDict('a=1', mutable=True)
>>> q.update({'a': '2'})
@ -543,7 +555,9 @@ a subclass of dictionary. Exceptions are outlined here:
Like :meth:`dict.items`, except this uses the same last-value logic as
:meth:`__getitem__` and returns an iterator object instead of a view object.
For example::
For example:
.. code-block:: pycon
>>> q = QueryDict('a=1&a=2&a=3')
>>> list(q.items())
@ -553,7 +567,9 @@ a subclass of dictionary. Exceptions are outlined here:
Like :meth:`dict.values`, except this uses the same last-value logic as
:meth:`__getitem__` and returns an iterator instead of a view object. For
example::
example:
.. code-block:: pycon
>>> q = QueryDict('a=1&a=2&a=3')
>>> list(q.values())
@ -588,7 +604,9 @@ In addition, ``QueryDict`` has the following methods:
.. method:: QueryDict.lists()
Like :meth:`items()`, except it includes all values, as a list, for each
member of the dictionary. For example::
member of the dictionary. For example:
.. code-block:: pycon
>>> q = QueryDict('a=1&a=2&a=3')
>>> q.lists()
@ -597,7 +615,9 @@ In addition, ``QueryDict`` has the following methods:
.. method:: QueryDict.pop(key)
Returns a list of values for the given key and removes them from the
dictionary. Raises ``KeyError`` if the key does not exist. For example::
dictionary. Raises ``KeyError`` if the key does not exist. For example:
.. code-block:: pycon
>>> q = QueryDict('a=1&a=2&a=3', mutable=True)
>>> q.pop('a')
@ -608,7 +628,9 @@ In addition, ``QueryDict`` has the following methods:
Removes an arbitrary member of the dictionary (since there's no concept
of ordering), and returns a two value tuple containing the key and a list
of all values for the key. Raises ``KeyError`` when called on an empty
dictionary. For example::
dictionary. For example:
.. code-block:: pycon
>>> q = QueryDict('a=1&a=2&a=3', mutable=True)
>>> q.popitem()
@ -618,7 +640,9 @@ In addition, ``QueryDict`` has the following methods:
Returns a ``dict`` representation of ``QueryDict``. For every (key, list)
pair in ``QueryDict``, ``dict`` will have (key, item), where item is one
element of the list, using the same logic as :meth:`QueryDict.__getitem__`::
element of the list, using the same logic as :meth:`QueryDict.__getitem__`:
.. code-block:: pycon
>>> q = QueryDict('a=1&a=3&a=5')
>>> q.dict()
@ -626,14 +650,18 @@ In addition, ``QueryDict`` has the following methods:
.. method:: QueryDict.urlencode(safe=None)
Returns a string of the data in query string format. For example::
Returns a string of the data in query string format. For example:
.. code-block:: pycon
>>> q = QueryDict('a=2&b=3&b=5')
>>> q.urlencode()
'a=2&b=3&b=5'
Use the ``safe`` parameter to pass characters which don't require encoding.
For example::
For example:
.. code-block:: pycon
>>> q = QueryDict(mutable=True)
>>> q['next'] = '/a&b/'
@ -659,7 +687,9 @@ Passing strings
~~~~~~~~~~~~~~~
Typical usage is to pass the contents of the page, as a string, bytestring,
or :class:`memoryview`, to the :class:`HttpResponse` constructor::
or :class:`memoryview`, to the :class:`HttpResponse` constructor:
.. code-block:: pycon
>>> from django.http import HttpResponse
>>> response = HttpResponse("Here's the text of the web page.")
@ -668,7 +698,9 @@ or :class:`memoryview`, to the :class:`HttpResponse` constructor::
>>> response = HttpResponse(memoryview(b'Memoryview as well.'))
But if you want to add content incrementally, you can use ``response`` as a
file-like object::
file-like object:
.. code-block:: pycon
>>> response = HttpResponse()
>>> response.write("<p>Here's the text of the web page.</p>")
@ -691,13 +723,17 @@ Setting header fields
~~~~~~~~~~~~~~~~~~~~~
To set or remove a header field in your response, use
:attr:`HttpResponse.headers`::
:attr:`HttpResponse.headers`:
.. code-block:: pycon
>>> response = HttpResponse()
>>> response.headers['Age'] = 120
>>> del response.headers['Age']
You can also manipulate headers by treating your response like a dictionary::
You can also manipulate headers by treating your response like a dictionary:
.. code-block:: pycon
>>> response = HttpResponse()
>>> response['Age'] = 120
@ -709,7 +745,9 @@ by ``HttpResponse``.
When using this interface, unlike a dictionary, ``del`` doesn't raise
``KeyError`` if the header field doesn't exist.
You can also set headers on instantiation::
You can also set headers on instantiation:
.. code-block:: pycon
>>> response = HttpResponse(headers={'Age': 120})
@ -728,7 +766,9 @@ Telling the browser to treat the response as a file attachment
To tell the browser to treat the response as a file attachment, set the
``Content-Type`` and ``Content-Disposition`` headers. For example, this is how
you might return a Microsoft Excel spreadsheet::
you might return a Microsoft Excel spreadsheet:
.. code-block:: pycon
>>> response = HttpResponse(my_data, headers={
... 'Content-Type': 'application/vnd.ms-excel',
@ -1025,7 +1065,9 @@ Custom response classes
~~~~~~~~~~~~~~~~~~~~~~~
If you find yourself needing a response class that Django doesn't provide, you
can create it with the help of :py:class:`http.HTTPStatus`. For example::
can create it with the help of :py:class:`http.HTTPStatus`. For example:
.. code-block:: pycon
from http import HTTPStatus
from django.http import HttpResponse
@ -1064,7 +1106,9 @@ can create it with the help of :py:class:`http.HTTPStatus`. For example::
Usage
-----
Typical usage could look like::
Typical usage could look like:
.. code-block:: pycon
>>> from django.http import JsonResponse
>>> response = JsonResponse({'foo': 'bar'})
@ -1075,7 +1119,9 @@ Serializing non-dictionary objects
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In order to serialize objects other than ``dict`` you must set the ``safe``
parameter to ``False``::
parameter to ``False``:
.. code-block:: pycon
>>> response = JsonResponse([1, 2, 3], safe=False)
@ -1099,7 +1145,9 @@ Changing the default JSON encoder
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
If you need to use a different JSON encoder class you can pass the ``encoder``
parameter to the constructor method::
parameter to the constructor method:
.. code-block:: pycon
>>> response = JsonResponse(data, encoder=MyJSONEncoder)
@ -1244,7 +1292,9 @@ Attributes
when they can be guessed from contents of ``open_file``.
``FileResponse`` accepts any file-like object with binary content, for example
a file open in binary mode like so::
a file open in binary mode like so:
.. code-block:: pycon
>>> from django.http import FileResponse
>>> response = FileResponse(open('myfile.png', 'rb'))

View File

@ -1685,7 +1685,9 @@ formats defined in this file.
For example, if :setting:`FORMAT_MODULE_PATH` is set to ``mysite.formats``,
and current language is ``en`` (English), Django will expect a directory tree
like::
like:
.. code-block:: text
mysite/
formats/

View File

@ -325,7 +325,9 @@ If we connected a handler like this::
m2m_changed.connect(toppings_changed, sender=Pizza.toppings.through)
and then did something like this::
and then did something like this:
.. code-block:: pycon
>>> p = Pizza.objects.create(...)
>>> t = Topping.objects.create(...)
@ -355,7 +357,9 @@ Argument Value
``using`` ``"default"`` (since the default router sends writes here)
============== ============================================================
And if we would then do something like this::
And if we would then do something like this:
.. code-block:: pycon
>>> t.pizza_set.remove(p)

View File

@ -218,7 +218,9 @@ subsequent rendering calls do not change the response content.
However, when ``response.content`` is explicitly assigned, the
change is always applied. If you want to force the content to be
re-rendered, you can reevaluate the rendered content, and assign
the content of the response manually::
the content of the response manually:
.. code-block:: pycon
# Set up a rendered TemplateResponse
>>> from django.template.response import TemplateResponse

View File

@ -211,7 +211,9 @@ different contexts.
.. method:: Template.render(context)
Call the :class:`Template` object's ``render()`` method with a
:class:`Context` to "fill" the template::
:class:`Context` to "fill" the template:
.. code-block:: pycon
>>> from django.template import Context, Template
>>> template = Template("My name is {{ my_name }}.")
@ -243,7 +245,9 @@ interpreted as a literal string and not using the value of the variable "bar",
if one exists in the template context.
The template system uses the first lookup type that works. It's short-circuit
logic. Here are a few examples::
logic. Here are a few examples:
.. code-block:: pycon
>>> from django.template import Context, Template
>>> t = Template("My name is {{ person.first_name }}.")
@ -264,7 +268,9 @@ logic. Here are a few examples::
"The first stooge in the list is Larry."
If any part of the variable is callable, the template system will try calling
it. Example::
it. Example:
.. code-block:: pycon
>>> class PersonClass2:
... def name(self):
@ -282,7 +288,9 @@ straight lookups. Here are some things to keep in mind:
*does* have a ``silent_variable_failure`` attribute whose value is
``True``, the variable will render as the value of the engine's
``string_if_invalid`` configuration option (an empty string, by default).
Example::
Example:
.. code-block:: pycon
>>> t = Template("My name is {{ person.first_name }}.")
>>> class PersonClass3:
@ -320,9 +328,11 @@ straight lookups. Here are some things to keep in mind:
A good example is the :meth:`~django.db.models.Model.delete` method on
each Django model object. The template system shouldn't be allowed to do
something like this::
something like this:
I will now delete this valuable data. {{ data.delete }}
.. code-block:: html+django
I will now delete this valuable data. {{ data.delete }}
To prevent this, set an ``alters_data`` attribute on the callable
variable. The template system won't call a variable if it has
@ -395,14 +405,18 @@ A similar issue exists if you want to include these sequences in template filter
or tag arguments. For example, when parsing a block tag, Django's template
parser looks for the first occurrence of ``%}`` after a ``{%``. This prevents
the use of ``"%}"`` as a string literal. For example, a ``TemplateSyntaxError``
will be raised for the following expressions::
will be raised for the following expressions:
.. code-block:: html+django
{% include "template.html" tvar="Some string literal with %} in it." %}
{% with tvar="Some string literal with %} in it." %}{% endwith %}
The same issue can be triggered by using a reserved sequence in filter
arguments::
arguments:
.. code-block:: html+django
{{ some.variable|default:"}}" }}
@ -417,7 +431,9 @@ Playing with ``Context`` objects
Most of the time, you'll instantiate :class:`Context` objects by passing in a
fully-populated dictionary to ``Context()``. But you can add and delete items
from a ``Context`` object once it's been instantiated, too, using standard
dictionary syntax::
dictionary syntax:
.. code-block:: pycon
>>> from django.template import Context
>>> c = Context({"foo": "bar"})
@ -448,7 +464,9 @@ dictionary syntax::
A ``Context`` object is a stack. That is, you can ``push()`` and ``pop()`` it.
If you ``pop()`` too much, it'll raise
``django.template.ContextPopException``::
``django.template.ContextPopException``:
.. code-block:: pycon
>>> c = Context()
>>> c['foo'] = 'first level'

File diff suppressed because it is too large Load Diff

View File

@ -34,8 +34,6 @@ or Jinja2_, you should feel right at home with Django's templates.
Templates
=========
.. highlight:: html+django
A template is a text file. It can generate any text-based format (HTML, XML,
CSV, etc.).
@ -100,7 +98,9 @@ Use a dot (``.``) to access attributes of a variable.
This lookup order can cause some unexpected behavior with objects that
override dictionary lookup. For example, consider the following code snippet
that attempts to loop over a ``collections.defaultdict``::
that attempts to loop over a ``collections.defaultdict``:
.. code-block:: html+django
{% for k, v in defaultdict.items %}
Do something with k and v here...
@ -151,7 +151,9 @@ used template filters:
:tfilter:`default`
If a variable is false or empty, use given default. Otherwise, use the
value of the variable. For example::
value of the variable. For example:
.. code-block:: html+django
{{ value|default:"nothing" }}
@ -160,7 +162,9 @@ used template filters:
:tfilter:`length`
Returns the length of the value. This works for both strings and lists.
For example::
For example:
.. code-block:: html+django
{{ value|length }}
@ -168,7 +172,9 @@ used template filters:
:tfilter:`filesizeformat`
Formats the value like a "human-readable" file size (i.e. ``'13 KB'``,
``'4.1 MB'``, ``'102 bytes'``, etc.). For example::
``'4.1 MB'``, ``'102 bytes'``, etc.). For example:
.. code-block:: html+django
{{ value|filesizeformat }}
@ -203,7 +209,9 @@ tags:
:ttag:`for`
Loop over each item in an array. For example, to display a list of athletes
provided in ``athlete_list``::
provided in ``athlete_list``:
.. code-block:: html+django
<ul>
{% for athlete in athlete_list %}
@ -213,7 +221,9 @@ tags:
:ttag:`if`, ``elif``, and ``else``
Evaluates a variable, and if that variable is "true" the contents of the
block are displayed::
block are displayed:
.. code-block:: html+django
{% if athlete_list %}
Number of athletes: {{ athlete_list|length }}
@ -229,7 +239,9 @@ tags:
should be out..." will be displayed. If both lists are empty,
"No athletes." will be displayed.
You can also use filters and various operators in the :ttag:`if` tag::
You can also use filters and various operators in the :ttag:`if` tag:
.. code-block:: html+django
{% if athlete_list|length > 1 %}
Team: {% for athlete in athlete_list %} ... {% endfor %}
@ -264,11 +276,15 @@ Comments
To comment-out part of a line in a template, use the comment syntax: ``{# #}``.
For example, this template would render as ``'hello'``::
For example, this template would render as ``'hello'``:
.. code-block:: html+django
{# greeting #}hello
A comment can contain any template code, invalid or not. For example::
A comment can contain any template code, invalid or not. For example:
.. code-block:: html+django
{# {% if foo %}bar{% else %} #}
@ -286,7 +302,9 @@ engine is template inheritance. Template inheritance allows you to build a base
"skeleton" template that contains all the common elements of your site and
defines **blocks** that child templates can override.
Let's look at template inheritance by starting with an example::
Let's look at template inheritance by starting with an example:
.. code-block:: html+django
<!DOCTYPE html>
<html lang="en">
@ -319,7 +337,9 @@ In this example, the :ttag:`block` tag defines three blocks that child
templates can fill in. All the :ttag:`block` tag does is to tell the template
engine that a child template may override those portions of the template.
A child template might look like this::
A child template might look like this:
.. code-block:: html+django
{% extends "base.html" %}
@ -339,7 +359,9 @@ this template, first it locates the parent -- in this case, "base.html".
At that point, the template engine will notice the three :ttag:`block` tags
in ``base.html`` and replace those blocks with the contents of the child
template. Depending on the value of ``blog_entries``, the output might look
like::
like:
.. code-block:: html+django
<!DOCTYPE html>
<html lang="en">
@ -416,13 +438,17 @@ Here are some tips for working with inheritance:
* Variables created outside of a :ttag:`{% block %}<block>` using the template
tag ``as`` syntax can't be used inside the block. For example, this template
doesn't render anything::
doesn't render anything:
.. code-block:: html+django
{% translate "Title" as title %}
{% block content %}{{ title }}{% endblock %}
* For extra readability, you can optionally give a *name* to your
``{% endblock %}`` tag. For example::
``{% endblock %}`` tag. For example:
.. code-block:: html+django
{% block content %}
...
@ -434,7 +460,9 @@ Here are some tips for working with inheritance:
* :ttag:`{% block %}<block>` tags are evaluated first. That's why the content
of a block is always overridden, regardless of the truthiness of surrounding
tags. For example, this template will *always* override the content of the
``title`` block::
``title`` block:
.. code-block:: html+django
{% if change_title %}
{% block title %}Hello!{% endblock title %}
@ -455,16 +483,22 @@ Automatic HTML escaping
When generating HTML from templates, there's always a risk that a variable will
include characters that affect the resulting HTML. For example, consider this
template fragment::
template fragment:
.. code-block:: html+django
Hello, {{ name }}
At first, this seems like a harmless way to display a user's name, but consider
what would happen if the user entered their name as this::
what would happen if the user entered their name as this:
.. code-block:: html+django
<script>alert('hello')</script>
With this name value, the template would be rendered as::
With this name value, the template would be rendered as:
.. code-block:: html+django
Hello, <script>alert('hello')</script>
@ -476,7 +510,9 @@ Similarly, what if the name contained a ``'<'`` symbol, like this?
<b>username
That would result in a rendered template like this::
That would result in a rendered template like this:
.. code-block:: html+django
Hello, <b>username
@ -531,14 +567,18 @@ For individual variables
~~~~~~~~~~~~~~~~~~~~~~~~
To disable auto-escaping for an individual variable, use the :tfilter:`safe`
filter::
filter:
.. code-block:: html+django
This will be escaped: {{ data }}
This will not be escaped: {{ data|safe }}
Think of *safe* as shorthand for *safe from further escaping* or *can be
safely interpreted as HTML*. In this example, if ``data`` contains ``'<b>'``,
the output will be::
the output will be:
.. code-block:: html+django
This will be escaped: &lt;b&gt;
This will not be escaped: <b>
@ -547,7 +587,9 @@ For template blocks
~~~~~~~~~~~~~~~~~~~
To control auto-escaping for a template, wrap the template (or a particular
section of the template) in the :ttag:`autoescape` tag, like so::
section of the template) in the :ttag:`autoescape` tag, like so:
.. code-block:: html+django
{% autoescape off %}
Hello {{ name }}
@ -555,7 +597,9 @@ section of the template) in the :ttag:`autoescape` tag, like so::
The :ttag:`autoescape` tag takes either ``on`` or ``off`` as its argument. At
times, you might want to force auto-escaping when it would otherwise be
disabled. Here is an example template::
disabled. Here is an example template:
.. code-block:: html+django
Auto-escaping is on by default. Hello {{ name }}
@ -590,7 +634,9 @@ just like all block tags. For example:
Because auto-escaping is turned off in the base template, it will also be
turned off in the child template, resulting in the following rendered
HTML when the ``greeting`` variable contains the string ``<b>Hello!</b>``::
HTML when the ``greeting`` variable contains the string ``<b>Hello!</b>``:
.. code-block:: html+django
<h1>This &amp; that</h1>
<b>Hello!</b>
@ -614,7 +660,9 @@ danger of the :tfilter:`escape` filter *double-escaping* data -- the
String literals and automatic escaping
--------------------------------------
As we mentioned earlier, filter arguments can be strings::
As we mentioned earlier, filter arguments can be strings:
.. code-block:: html+django
{{ data|default:"This is a string literal." }}
@ -624,11 +672,15 @@ filter. The reasoning behind this is that the template author is in control of
what goes into the string literal, so they can make sure the text is correctly
escaped when the template is written.
This means you would write ::
This means you would write :
.. code-block:: html+django
{{ data|default:"3 &lt; 2" }}
...rather than::
...rather than:
.. code-block:: html+django
{{ data|default:"3 < 2" }} {# Bad! Don't do this. #}
@ -647,7 +699,9 @@ This means that templates have access to much more than just class attributes
ORM provides the :ref:`"entry_set"<topics-db-queries-related>` syntax for
finding a collection of objects related on a foreign key. Therefore, given
a model called "comment" with a foreign key relationship to a model called
"task" you can loop through all comments attached to a given task like this::
"task" you can loop through all comments attached to a given task like this:
.. code-block:: html+django
{% for comment in task.comment_set.all %}
{{ comment }}
@ -655,7 +709,9 @@ a model called "comment" with a foreign key relationship to a model called
Similarly, :doc:`QuerySets</ref/models/querysets>` provide a ``count()`` method
to count the number of objects they contain. Therefore, you can obtain a count
of all comments related to the current task with::
of all comments related to the current task with:
.. code-block:: html+django
{{ task.comment_set.all.count }}
@ -686,7 +742,9 @@ Custom tag and filter libraries
Certain applications provide custom tag and filter libraries. To access them in
a template, ensure the application is in :setting:`INSTALLED_APPS` (we'd add
``'django.contrib.humanize'`` for this example), and then use the :ttag:`load`
tag in a template::
tag in a template:
.. code-block:: html+django
{% load humanize %}
@ -698,7 +756,9 @@ makes the ``intcomma`` filter available for use. If you've enabled
admin to find the list of custom libraries in your installation.
The :ttag:`load` tag can take multiple library names, separated by spaces.
Example::
Example:
.. code-block:: html+django
{% load humanize i18n %}

View File

@ -174,7 +174,9 @@ further encoded when passed to ``iri_to_uri()``. This means you can pass a
full URL to this function and it will not mess up the query string or anything
like that.
An example might clarify things here::
An example might clarify things here:
.. code-block:: pycon
>>> from urllib.parse import quote
>>> from django.utils.encoding import iri_to_uri
@ -193,7 +195,9 @@ result.
Similarly, Django provides :func:`django.utils.encoding.uri_to_iri()` which
implements the conversion from URI to IRI as per :rfc:`3987#section-3.2`.
An example to demonstrate::
An example to demonstrate:
.. code-block:: pycon
>>> from django.utils.encoding import uri_to_iri
>>> uri_to_iri('/%E2%99%A5%E2%99%A5/?utf8=%E2%9C%93')
@ -309,7 +313,9 @@ and application server for the appropriate syntax and location to set this
variable. See the :doc:`/howto/deployment/wsgi/modwsgi` for examples.
In your development environment, you might need to add a setting to your
``~.bashrc`` analogous to:::
``~.bashrc`` analogous to:
.. code-block:: shell
export LANG="en_US.UTF-8"

View File

@ -36,7 +36,9 @@ If the URL accepts arguments, you may pass them in ``args``. For example::
def myview(request):
return HttpResponseRedirect(reverse('arch-summary', args=[1945]))
You can also pass ``kwargs`` instead of ``args``. For example::
You can also pass ``kwargs`` instead of ``args``. For example:
.. code-block:: pycon
>>> reverse('admin:app_list', kwargs={'app_label': 'auth'})
'/admin/auth/'
@ -65,7 +67,9 @@ use for reversing. By default, the root URLconf for the current thread is used.
.. note::
The string returned by ``reverse()`` is already
:ref:`urlquoted <uri-and-iri-handling>`. For example::
:ref:`urlquoted <uri-and-iri-handling>`. For example:
.. code-block:: pycon
>>> reverse('cities', args=['Orléans'])
'.../Orl%C3%A9ans/'

View File

@ -298,7 +298,9 @@ The functions defined in this module share the following properties:
.. module:: django.utils.feedgenerator
:synopsis: Syndication feed generation library -- used for generating RSS, etc.
Sample usage::
Sample usage:
.. code-block:: pycon
>>> from django.utils import feedgenerator
>>> feed = feedgenerator.Rss201rev2Feed(
@ -655,9 +657,11 @@ escaping HTML.
Escapes all HTML/XML special characters with their Unicode escapes, so
value is safe for use with JavaScript. Also wraps the escaped JSON in a
``<script>`` tag. If the ``element_id`` parameter is not ``None``, the
``<script>`` tag is given the passed id. For example::
``<script>`` tag is given the passed id. For example:
>> json_script({"hello": "world"}, element_id="hello-data")
.. code-block:: pycon
>>> json_script({"hello": "world"}, element_id="hello-data")
'<script id="hello-data" type="application/json">{"hello": "world"}</script>'
The ``encoder``, which defaults to
@ -797,7 +801,9 @@ appropriate entities.
For building up fragments of HTML, you should normally be using
:func:`django.utils.html.format_html` instead.
String marked safe will become unsafe again if modified. For example::
String marked safe will become unsafe again if modified. For example:
.. code-block:: pycon
>>> mystr = '<b>Hello World</b> '
>>> mystr = mark_safe(mystr)
@ -843,13 +849,17 @@ appropriate entities.
#. Replacing any whitespace or repeated dashes with single dashes.
#. Removing leading and trailing whitespace, dashes, and underscores.
For example::
For example:
.. code-block:: pycon
>>> slugify(' Joel is a slug ')
'joel-is-a-slug'
If you want to allow Unicode characters, pass ``allow_unicode=True``. For
example::
example:
.. code-block:: pycon
>>> slugify('你好 World', allow_unicode=True)
'你好-world'

View File

@ -2,8 +2,6 @@
Porting your apps from Django 0.96 to 1.0
=========================================
.. highlight:: python
Django 1.0 breaks compatibility with 0.96 in some areas.
This guide will help you port 0.96 projects and apps to 1.0. The first part of

View File

@ -166,14 +166,18 @@ running your Django code. For example, Jupyter_ notebooks and IPython_
interactive shells both transparently provide an active event loop so that it is
easier to interact with asynchronous APIs.
If you're using an IPython shell, you can disable this event loop by running::
If you're using an IPython shell, you can disable this event loop by running:
.. code-block:: shell
%autoawait off
as a command at the IPython prompt. This will allow you to run synchronous code
without generating :exc:`~django.core.exceptions.SynchronousOnlyOperation`
errors; however, you also won't be able to ``await`` asynchronous APIs. To turn
the event loop back on, run::
the event loop back on, run:
.. code-block:: shell
%autoawait on

View File

@ -323,7 +323,9 @@ you might create an Employee model::
Assuming an existing Employee Fred Smith who has both a User and Employee
model, you can access the related information using Django's standard related
model conventions::
model conventions:
.. code-block:: pycon
>>> u = User.objects.get(username='fsmith')
>>> freds_department = u.employee.department

View File

@ -46,7 +46,9 @@ Creating users
--------------
The most direct way to create users is to use the included
:meth:`~django.contrib.auth.models.UserManager.create_user` helper function::
:meth:`~django.contrib.auth.models.UserManager.create_user` helper function:
.. code-block:: pycon
>>> from django.contrib.auth.models import User
>>> user = User.objects.create_user('john', 'lennon@thebeatles.com', 'johnpassword')
@ -65,7 +67,9 @@ interactively <auth-admin>`.
Creating superusers
-------------------
Create superusers using the :djadmin:`createsuperuser` command::
Create superusers using the :djadmin:`createsuperuser` command:
.. console::
$ python manage.py createsuperuser --username=joe --email=joe@example.com
@ -330,6 +334,8 @@ inherit the permissions of the concrete model they subclass::
proxy = True
permissions = [('can_deliver_pizzas', 'Can deliver pizzas')]
.. code-block:: pycon
>>> # Fetch the content type for the proxy model.
>>> content_type = ContentType.objects.get_for_model(Student, for_concrete_model=False)
>>> student_permissions = Permission.objects.filter(content_type=content_type)
@ -1723,13 +1729,17 @@ template-friendly proxy of permissions.
Evaluating a single-attribute lookup of ``{{ perms }}`` as a boolean is a proxy
to :meth:`User.has_module_perms()
<django.contrib.auth.models.User.has_module_perms>`. For example, to check if
the logged-in user has any permissions in the ``foo`` app::
the logged-in user has any permissions in the ``foo`` app:
.. code-block:: html+django
{% if perms.foo %}
Evaluating a two-level-attribute lookup as a boolean is a proxy to
:meth:`User.has_perm() <django.contrib.auth.models.User.has_perm>`. For example,
to check if the logged-in user has the permission ``foo.add_vote``::
to check if the logged-in user has the permission ``foo.add_vote``:
.. code-block:: html+django
{% if perms.foo.add_vote %}

View File

@ -264,7 +264,9 @@ Creating the cache table
~~~~~~~~~~~~~~~~~~~~~~~~
Before using the database cache, you must create the cache table with this
command::
command:
.. code-block:: shell
python manage.py createcachetable
@ -840,8 +842,6 @@ a cached item, for example:
The low-level cache API
=======================
.. highlight:: python
Sometimes, caching an entire rendered page doesn't gain you very much and is,
in fact, inconvenient overkill.
@ -884,7 +884,9 @@ Accessing the cache
.. data:: django.core.cache.cache
As a shortcut, the default cache is available as
``django.core.cache.cache``::
``django.core.cache.cache``:
.. code-block:: pycon
>>> from django.core.cache import cache
@ -916,14 +918,18 @@ It's the number of seconds the value should be stored in the cache. Passing in
``None`` for ``timeout`` will cache the value forever. A ``timeout`` of ``0``
won't cache the value.
If the object doesn't exist in the cache, ``cache.get()`` returns ``None``::
If the object doesn't exist in the cache, ``cache.get()`` returns ``None``:
.. code-block:: pycon
>>> # Wait 30 seconds for 'my_key' to expire...
>>> cache.get('my_key')
None
If you need to determine whether the object exists in the cache and you have
stored a literal value ``None``, use a sentinel object as the default::
stored a literal value ``None``, use a sentinel object as the default:
.. code-block:: pycon
>>> sentinel = object()
>>> cache.get('my_key', sentinel) is sentinel
@ -933,7 +939,9 @@ stored a literal value ``None``, use a sentinel object as the default::
True
``cache.get()`` can take a ``default`` argument. This specifies which value to
return if the object doesn't exist in the cache::
return if the object doesn't exist in the cache:
.. code-block:: pycon
>>> cache.get('my_key', 'has expired')
'has expired'
@ -942,7 +950,9 @@ return if the object doesn't exist in the cache::
To add a key only if it doesn't already exist, use the ``add()`` method.
It takes the same parameters as ``set()``, but it will not attempt to
update the cache if the key specified is already present::
update the cache if the key specified is already present:
.. code-block:: pycon
>>> cache.set('add_key', 'Initial value')
>>> cache.add('add_key', 'New value')
@ -958,13 +968,17 @@ check the return value. It will return ``True`` if the value was stored,
If you want to get a key's value or set a value if the key isn't in the cache,
there is the ``get_or_set()`` method. It takes the same parameters as ``get()``
but the default is set as the new cache value for that key, rather than
returned::
returned:
.. code-block:: pycon
>>> cache.get('my_new_key') # returns None
>>> cache.get_or_set('my_new_key', 'my new value', 100)
'my new value'
You can also pass any callable as a *default* value::
You can also pass any callable as a *default* value:
.. code-block:: pycon
>>> import datetime
>>> cache.get_or_set('some-timestamp-key', datetime.datetime.now)
@ -974,7 +988,9 @@ You can also pass any callable as a *default* value::
There's also a ``get_many()`` interface that only hits the cache once.
``get_many()`` returns a dictionary with all the keys you asked for that
actually exist in the cache (and haven't expired)::
actually exist in the cache (and haven't expired):
.. code-block:: pycon
>>> cache.set('a', 1)
>>> cache.set('b', 2)
@ -985,7 +1001,9 @@ actually exist in the cache (and haven't expired)::
.. method:: cache.set_many(dict, timeout)
To set multiple values more efficiently, use ``set_many()`` to pass a dictionary
of key-value pairs::
of key-value pairs:
.. code-block:: pycon
>>> cache.set_many({'a': 1, 'b': 2, 'c': 3})
>>> cache.get_many(['a', 'b', 'c'])
@ -999,7 +1017,9 @@ failed to be inserted.
.. method:: cache.delete(key, version=None)
You can delete keys explicitly with ``delete()`` to clear the cache for a
particular object::
particular object:
.. code-block:: pycon
>>> cache.delete('a')
True
@ -1010,7 +1030,9 @@ otherwise.
.. method:: cache.delete_many(keys, version=None)
If you want to clear a bunch of keys at once, ``delete_many()`` can take a list
of keys to be cleared::
of keys to be cleared:
.. code-block:: pycon
>>> cache.delete_many(['a', 'b', 'c'])
@ -1018,14 +1040,18 @@ of keys to be cleared::
Finally, if you want to delete all the keys in the cache, use
``cache.clear()``. Be careful with this; ``clear()`` will remove *everything*
from the cache, not just the keys set by your application. ::
from the cache, not just the keys set by your application. :
.. code-block:: pycon
>>> cache.clear()
.. method:: cache.touch(key, timeout=DEFAULT_TIMEOUT, version=None)
``cache.touch()`` sets a new expiration for a key. For example, to update a key
to expire 10 seconds from now::
to expire 10 seconds from now:
.. code-block:: pycon
>>> cache.touch('a', 10)
True
@ -1044,7 +1070,9 @@ You can also increment or decrement a key that already exists using the
value will be incremented or decremented by 1. Other increment/decrement values
can be specified by providing an argument to the increment/decrement call. A
ValueError will be raised if you attempt to increment or decrement a
nonexistent cache key.::
nonexistent cache key:
.. code-block:: pycon
>>> cache.set('num', 1)
>>> cache.incr('num')
@ -1120,7 +1148,9 @@ prefix and the user-provided cache key to obtain the final cache key.
By default, any key request will automatically include the site
default cache key version. However, the primitive cache functions all
include a ``version`` argument, so you can specify a particular cache
key version to set or get. For example::
key version to set or get. For example:
.. code-block:: pycon
>>> # Set version 2 of a cache key
>>> cache.set('my_key', 'hello world!', version=2)
@ -1134,7 +1164,9 @@ key version to set or get. For example::
The version of a specific key can be incremented and decremented using
the ``incr_version()`` and ``decr_version()`` methods. This
enables specific keys to be bumped to a new version, leaving other
keys unaffected. Continuing our previous example::
keys unaffected. Continuing our previous example:
.. code-block:: pycon
>>> # Increment the version of 'my_key'
>>> cache.incr_version('my_key')
@ -1218,7 +1250,9 @@ yet support asynchronous caching. It will be coming in a future release.
``django.core.cache.backends.base.BaseCache`` has async variants of :ref:`all
base methods <cache-basic-interface>`. By convention, the asynchronous versions
of all methods are prefixed with ``a``. By default, the arguments for both
variants are the same::
variants are the same:
.. code-block:: pycon
>>> await cache.aset('num', 1)
>>> await cache.ahas_key('num')

View File

@ -44,7 +44,9 @@ Cheat sheet
===========
In a hurry? Here's how to do common aggregate queries, assuming the models
above::
above:
.. code-block:: pycon
# Total number of books.
>>> Book.objects.count()
@ -102,19 +104,25 @@ Generating aggregates over a ``QuerySet``
Django provides two ways to generate aggregates. The first way is to generate
summary values over an entire ``QuerySet``. For example, say you wanted to
calculate the average price of all books available for sale. Django's query
syntax provides a means for describing the set of all books::
syntax provides a means for describing the set of all books:
.. code-block:: pycon
>>> Book.objects.all()
What we need is a way to calculate summary values over the objects that
belong to this ``QuerySet``. This is done by appending an ``aggregate()``
clause onto the ``QuerySet``::
clause onto the ``QuerySet``:
.. code-block:: pycon
>>> from django.db.models import Avg
>>> Book.objects.all().aggregate(Avg('price'))
{'price__avg': 34.35}
The ``all()`` is redundant in this example, so this could be simplified to::
The ``all()`` is redundant in this example, so this could be simplified to:
.. code-block:: pycon
>>> Book.objects.aggregate(Avg('price'))
{'price__avg': 34.35}
@ -129,14 +137,18 @@ returns a dictionary of name-value pairs. The name is an identifier for the
aggregate value; the value is the computed aggregate. The name is
automatically generated from the name of the field and the aggregate function.
If you want to manually specify a name for the aggregate value, you can do so
by providing that name when you specify the aggregate clause::
by providing that name when you specify the aggregate clause:
.. code-block:: pycon
>>> Book.objects.aggregate(average_price=Avg('price'))
{'average_price': 34.35}
If you want to generate more than one aggregate, you add another argument to
the ``aggregate()`` clause. So, if we also wanted to know the maximum and
minimum price of all books, we would issue the query::
minimum price of all books, we would issue the query:
.. code-block:: pycon
>>> from django.db.models import Avg, Max, Min
>>> Book.objects.aggregate(Avg('price'), Max('price'), Min('price'))
@ -159,7 +171,9 @@ specified values.
The syntax for these annotations is identical to that used for the
:meth:`~.QuerySet.aggregate` clause. Each argument to ``annotate()`` describes
an aggregate that is to be calculated. For example, to annotate books with the
number of authors::
number of authors:
.. code-block:: pycon
# Build an annotated queryset
>>> from django.db.models import Count
@ -178,7 +192,9 @@ number of authors::
As with ``aggregate()``, the name for the annotation is automatically derived
from the name of the aggregate function and the name of the field being
aggregated. You can override this default name by providing an alias when you
specify the annotation::
specify the annotation:
.. code-block:: pycon
>>> q = Book.objects.annotate(num_authors=Count('authors'))
>>> q[0].num_authors
@ -239,7 +255,9 @@ filters. Django will then handle any table joins that are required to retrieve
and aggregate the related value.
For example, to find the price range of books offered in each store,
you could use the annotation::
you could use the annotation:
.. code-block:: pycon
>>> from django.db.models import Max, Min
>>> Store.objects.annotate(min_price=Min('books__price'), max_price=Max('books__price'))
@ -250,13 +268,17 @@ price field of the book model to produce a minimum and maximum value.
The same rules apply to the ``aggregate()`` clause. If you wanted to
know the lowest and highest price of any book that is available for sale
in any of the stores, you could use the aggregate::
in any of the stores, you could use the aggregate:
.. code-block:: pycon
>>> Store.objects.aggregate(min_price=Min('books__price'), max_price=Max('books__price'))
Join chains can be as deep as you require. For example, to extract the
age of the youngest author of any book available for sale, you could
issue the query::
issue the query:
.. code-block:: pycon
>>> Store.objects.aggregate(youngest_age=Min('books__authors__age'))
@ -270,7 +292,9 @@ of related models and double-underscores are used here too.
For example, we can ask for all publishers, annotated with their respective
total book stock counters (note how we use ``'book'`` to specify the
``Publisher`` -> ``Book`` reverse foreign key hop)::
``Publisher`` -> ``Book`` reverse foreign key hop):
.. code-block:: pycon
>>> from django.db.models import Avg, Count, Min, Sum
>>> Publisher.objects.annotate(Count('book'))
@ -278,7 +302,9 @@ total book stock counters (note how we use ``'book'`` to specify the
(Every ``Publisher`` in the resulting ``QuerySet`` will have an extra attribute
called ``book__count``.)
We can also ask for the oldest book of any of those managed by every publisher::
We can also ask for the oldest book of any of those managed by every publisher:
.. code-block:: pycon
>>> Publisher.objects.aggregate(oldest_pubdate=Min('book__pubdate'))
@ -288,7 +314,9 @@ such alias were specified, it would be the rather long ``'book__pubdate__min'``.
This doesn't apply just to foreign keys. It also works with many-to-many
relations. For example, we can ask for every author, annotated with the total
number of pages considering all the books the author has (co-)authored (note how we
use ``'book'`` to specify the ``Author`` -> ``Book`` reverse many-to-many hop)::
use ``'book'`` to specify the ``Author`` -> ``Book`` reverse many-to-many hop):
.. code-block:: pycon
>>> Author.objects.annotate(total_pages=Sum('book__pages'))
@ -297,7 +325,9 @@ called ``total_pages``. If no such alias were specified, it would be the rather
long ``book__pages__sum``.)
Or ask for the average rating of all the books written by author(s) we have on
file::
file:
.. code-block:: pycon
>>> Author.objects.aggregate(average_rating=Avg('book__rating'))
@ -317,7 +347,9 @@ constraining the objects that are considered for aggregation.
When used with an ``annotate()`` clause, a filter has the effect of
constraining the objects for which an annotation is calculated. For example,
you can generate an annotated list of all books that have a title starting
with "Django" using the query::
with "Django" using the query:
.. code-block:: pycon
>>> from django.db.models import Avg, Count
>>> Book.objects.filter(name__startswith="Django").annotate(num_authors=Count('authors'))
@ -325,7 +357,9 @@ with "Django" using the query::
When used with an ``aggregate()`` clause, a filter has the effect of
constraining the objects over which the aggregate is calculated.
For example, you can generate the average price of all books with a
title that starts with "Django" using the query::
title that starts with "Django" using the query:
.. code-block:: pycon
>>> Book.objects.filter(name__startswith="Django").aggregate(Avg('price'))
@ -339,7 +373,9 @@ used in ``filter()`` and ``exclude()`` clauses in the same way as any other
model field.
For example, to generate a list of books that have more than one author,
you can issue the query::
you can issue the query:
.. code-block:: pycon
>>> Book.objects.annotate(num_authors=Count('authors')).filter(num_authors__gt=1)
@ -348,7 +384,9 @@ based upon that annotation.
If you need two annotations with two separate filters you can use the
``filter`` argument with any aggregate. For example, to generate a list of
authors with a count of highly rated books::
authors with a count of highly rated books:
.. code-block:: pycon
>>> highly_rated = Count('book', filter=Q(book__rating__gte=7))
>>> Author.objects.annotate(num_books=Count('book'), highly_rated_books=highly_rated)
@ -381,7 +419,9 @@ Given:
* Publisher B has two books with ratings 1 and 4.
* Publisher C has one book with rating 1.
Here's an example with the ``Count`` aggregate::
Here's an example with the ``Count`` aggregate:
.. code-block:: pycon
>>> a, b = Publisher.objects.annotate(num_books=Count('book', distinct=True)).filter(book__rating__gt=3.0)
>>> a, a.num_books
@ -406,7 +446,9 @@ The second query counts the number of books that have a rating exceeding 3.0
for each publisher. The filter precedes the annotation, so the filter
constrains the objects considered when calculating the annotation.
Here's another example with the ``Avg`` aggregate::
Here's another example with the ``Avg`` aggregate:
.. code-block:: pycon
>>> a, b = Publisher.objects.annotate(avg_rating=Avg('book__rating')).filter(book__rating__gt=3.0)
>>> a, a.avg_rating
@ -437,7 +479,9 @@ define an ``order_by()`` clause, the aggregates you provide can reference
any alias defined as part of an ``annotate()`` clause in the query.
For example, to order a ``QuerySet`` of books by the number of authors
that have contributed to the book, you could use the following query::
that have contributed to the book, you could use the following query:
.. code-block:: pycon
>>> Book.objects.annotate(num_authors=Count('authors')).order_by('num_authors')
@ -462,7 +506,9 @@ rating of books written by each author:
This will return one result for each author in the database, annotated with
their average book rating.
However, the result will be slightly different if you use a ``values()`` clause::
However, the result will be slightly different if you use a ``values()`` clause:
.. code-block:: pycon
>>> Author.objects.values('name').annotate(average_rating=Avg('book__rating'))
@ -486,7 +532,9 @@ the ``values()`` clause only constrains the fields that are generated on
output.
For example, if we reverse the order of the ``values()`` and ``annotate()``
clause from our previous example::
clause from our previous example:
.. code-block:: pycon
>>> Author.objects.annotate(average_rating=Avg('book__rating')).values('name', 'average_rating')
@ -563,7 +611,9 @@ any alias defined as part of an ``annotate()`` clause in the query.
For example, if you wanted to calculate the average number of authors per
book you first annotate the set of books with the author count, then
aggregate that author count, referencing the annotation field::
aggregate that author count, referencing the annotation field:
.. code-block:: pycon
>>> from django.db.models import Avg, Count
>>> Book.objects.annotate(num_authors=Count('authors')).aggregate(Avg('num_authors'))

View File

@ -2,8 +2,6 @@
Many-to-many relationships
==========================
.. highlight:: pycon
To define a many-to-many relationship, use
:class:`~django.db.models.ManyToManyField`.
@ -36,7 +34,9 @@ objects, and a ``Publication`` has multiple ``Article`` objects:
What follows are examples of operations that can be performed using the Python
API facilities.
Create a few ``Publications``::
Create a few ``Publications``:
.. code-block:: pycon
>>> p1 = Publication(title='The Python Journal')
>>> p1.save()
@ -45,11 +45,15 @@ Create a few ``Publications``::
>>> p3 = Publication(title='Science Weekly')
>>> p3.save()
Create an ``Article``::
Create an ``Article``:
.. code-block:: pycon
>>> a1 = Article(headline='Django lets you build web apps easily')
You can't associate it with a ``Publication`` until it's been saved::
You can't associate it with a ``Publication`` until it's been saved:
.. code-block:: pycon
>>> a1.publications.add(p1)
Traceback (most recent call last):
@ -57,26 +61,35 @@ You can't associate it with a ``Publication`` until it's been saved::
ValueError: "<Article: Django lets you build web apps easily>" needs to have a value for field "id" before this many-to-many relationship can be used.
Save it!
::
.. code-block:: pycon
>>> a1.save()
Associate the ``Article`` with a ``Publication``::
Associate the ``Article`` with a ``Publication``:
.. code-block:: pycon
>>> a1.publications.add(p1)
Create another ``Article``, and set it to appear in the ``Publications``::
Create another ``Article``, and set it to appear in the ``Publications``:
.. code-block:: pycon
>>> a2 = Article(headline='NASA uses Python')
>>> a2.save()
>>> a2.publications.add(p1, p2)
>>> a2.publications.add(p3)
Adding a second time is OK, it will not duplicate the relation::
Adding a second time is OK, it will not duplicate the relation:
.. code-block:: pycon
>>> a2.publications.add(p3)
Adding an object of the wrong type raises :exc:`TypeError`::
Adding an object of the wrong type raises :exc:`TypeError`:
.. code-block:: pycon
>>> a2.publications.add(a1)
Traceback (most recent call last):
@ -84,18 +97,24 @@ Adding an object of the wrong type raises :exc:`TypeError`::
TypeError: 'Publication' instance expected
Create and add a ``Publication`` to an ``Article`` in one step using
:meth:`~django.db.models.fields.related.RelatedManager.create`::
:meth:`~django.db.models.fields.related.RelatedManager.create`:
.. code-block:: pycon
>>> new_publication = a2.publications.create(title='Highlights for Children')
``Article`` objects have access to their related ``Publication`` objects::
``Article`` objects have access to their related ``Publication`` objects:
.. code-block:: pycon
>>> a1.publications.all()
<QuerySet [<Publication: The Python Journal>]>
>>> a2.publications.all()
<QuerySet [<Publication: Highlights for Children>, <Publication: Science News>, <Publication: Science Weekly>, <Publication: The Python Journal>]>
``Publication`` objects have access to their related ``Article`` objects::
``Publication`` objects have access to their related ``Article`` objects:
.. code-block:: pycon
>>> p2.article_set.all()
<QuerySet [<Article: NASA uses Python>]>
@ -105,7 +124,9 @@ Create and add a ``Publication`` to an ``Article`` in one step using
<QuerySet [<Article: NASA uses Python>]>
Many-to-many relationships can be queried using :ref:`lookups across
relationships <lookups-that-span-relationships>`::
relationships <lookups-that-span-relationships>`:
.. code-block:: pycon
>>> Article.objects.filter(publications__id=1)
<QuerySet [<Article: Django lets you build web apps easily>, <Article: NASA uses Python>]>
@ -123,7 +144,9 @@ relationships <lookups-that-span-relationships>`::
<QuerySet [<Article: NASA uses Python>]>
The :meth:`~django.db.models.query.QuerySet.count` function respects
:meth:`~django.db.models.query.QuerySet.distinct` as well::
:meth:`~django.db.models.query.QuerySet.distinct` as well:
.. code-block:: pycon
>>> Article.objects.filter(publications__title__startswith="Science").count()
2
@ -137,7 +160,9 @@ The :meth:`~django.db.models.query.QuerySet.count` function respects
<QuerySet [<Article: Django lets you build web apps easily>, <Article: NASA uses Python>]>
Reverse m2m queries are supported (i.e., starting at the table that doesn't have
a :class:`~django.db.models.ManyToManyField`)::
a :class:`~django.db.models.ManyToManyField`):
.. code-block:: pycon
>>> Publication.objects.filter(id=1)
<QuerySet [<Publication: The Python Journal>]>
@ -162,12 +187,16 @@ a :class:`~django.db.models.ManyToManyField`)::
<QuerySet [<Publication: Highlights for Children>, <Publication: Science News>, <Publication: Science Weekly>, <Publication: The Python Journal>]>
Excluding a related item works as you would expect, too (although the SQL
involved is a little complex)::
involved is a little complex):
.. code-block:: pycon
>>> Article.objects.exclude(publications=p2)
<QuerySet [<Article: Django lets you build web apps easily>]>
If we delete a ``Publication``, its ``Articles`` won't be able to access it::
If we delete a ``Publication``, its ``Articles`` won't be able to access it:
.. code-block:: pycon
>>> p1.delete()
>>> Publication.objects.all()
@ -176,7 +205,9 @@ If we delete a ``Publication``, its ``Articles`` won't be able to access it::
>>> a1.publications.all()
<QuerySet []>
If we delete an ``Article``, its ``Publications`` won't be able to access it::
If we delete an ``Article``, its ``Publications`` won't be able to access it:
.. code-block:: pycon
>>> a2.delete()
>>> Article.objects.all()
@ -184,7 +215,9 @@ If we delete an ``Article``, its ``Publications`` won't be able to access it::
>>> p2.article_set.all()
<QuerySet []>
Adding via the 'other' end of an m2m::
Adding via the 'other' end of an m2m:
.. code-block:: pycon
>>> a4 = Article(headline='NASA finds intelligent life on Earth')
>>> a4.save()
@ -194,7 +227,9 @@ Adding via the 'other' end of an m2m::
>>> a4.publications.all()
<QuerySet [<Publication: Science News>]>
Adding via the other end using keywords::
Adding via the other end using keywords:
.. code-block:: pycon
>>> new_article = p2.article_set.create(headline='Oxygen-free diet works wonders')
>>> p2.article_set.all()
@ -203,7 +238,9 @@ Adding via the other end using keywords::
>>> a5.publications.all()
<QuerySet [<Publication: Science News>]>
Removing ``Publication`` from an ``Article``::
Removing ``Publication`` from an ``Article``:
.. code-block:: pycon
>>> a4.publications.remove(p2)
>>> p2.article_set.all()
@ -211,7 +248,9 @@ Removing ``Publication`` from an ``Article``::
>>> a4.publications.all()
<QuerySet []>
And from the other end::
And from the other end:
.. code-block:: pycon
>>> p2.article_set.remove(a5)
>>> p2.article_set.all()
@ -219,7 +258,9 @@ And from the other end::
>>> a5.publications.all()
<QuerySet []>
Relation sets can be set::
Relation sets can be set:
.. code-block:: pycon
>>> a4.publications.all()
<QuerySet [<Publication: Science News>]>
@ -227,13 +268,17 @@ Relation sets can be set::
>>> a4.publications.all()
<QuerySet [<Publication: Science Weekly>]>
Relation sets can be cleared::
Relation sets can be cleared:
.. code-block:: pycon
>>> p2.article_set.clear()
>>> p2.article_set.all()
<QuerySet []>
And you can clear from the other end::
And you can clear from the other end:
.. code-block:: pycon
>>> p2.article_set.add(a4, a5)
>>> p2.article_set.all()
@ -246,7 +291,9 @@ And you can clear from the other end::
>>> p2.article_set.all()
<QuerySet [<Article: Oxygen-free diet works wonders>]>
Recreate the ``Article`` and ``Publication`` we have deleted::
Recreate the ``Article`` and ``Publication`` we have deleted:
.. code-block:: pycon
>>> p1 = Publication(title='The Python Journal')
>>> p1.save()
@ -255,7 +302,9 @@ Recreate the ``Article`` and ``Publication`` we have deleted::
>>> a2.publications.add(p1, p2, p3)
Bulk delete some ``Publications`` - references to deleted publications should
go::
go:
.. code-block:: pycon
>>> Publication.objects.filter(title__startswith='Science').delete()
>>> Publication.objects.all()
@ -265,7 +314,9 @@ go::
>>> a2.publications.all()
<QuerySet [<Publication: The Python Journal>]>
Bulk delete some articles - references to deleted objects should go::
Bulk delete some articles - references to deleted objects should go:
.. code-block:: pycon
>>> q = Article.objects.filter(headline__startswith='Django')
>>> print(q)
@ -274,7 +325,9 @@ Bulk delete some articles - references to deleted objects should go::
After the :meth:`~django.db.models.query.QuerySet.delete`, the
:class:`~django.db.models.query.QuerySet` cache needs to be cleared, and the
referenced objects should be gone::
referenced objects should be gone:
.. code-block:: pycon
>>> print(q)
<QuerySet []>

View File

@ -31,9 +31,9 @@ objects, but an ``Article`` can only have one ``Reporter`` object::
What follows are examples of operations that can be performed using the Python
API facilities.
.. highlight:: pycon
Create a few Reporters:
Create a few Reporters::
.. code-block:: pycon
>>> r = Reporter(first_name='John', last_name='Smith', email='john@example.com')
>>> r.save()
@ -41,7 +41,9 @@ Create a few Reporters::
>>> r2 = Reporter(first_name='Paul', last_name='Jones', email='paul@example.com')
>>> r2.save()
Create an Article::
Create an Article:
.. code-block:: pycon
>>> from datetime import date
>>> a = Article(id=None, headline="This is a test", pub_date=date(2005, 7, 27), reporter=r)
@ -55,7 +57,9 @@ Create an Article::
Note that you must save an object before it can be assigned to a foreign key
relationship. For example, creating an ``Article`` with unsaved ``Reporter``
raises ``ValueError``::
raises ``ValueError``:
.. code-block:: pycon
>>> r3 = Reporter(first_name='John', last_name='Smith', email='john@example.com')
>>> Article.objects.create(headline="This is a test", pub_date=date(2005, 7, 27), reporter=r3)
@ -63,11 +67,15 @@ raises ``ValueError``::
...
ValueError: save() prohibited to prevent data loss due to unsaved related object 'reporter'.
Article objects have access to their related Reporter objects::
Article objects have access to their related Reporter objects:
.. code-block:: pycon
>>> r = a.reporter
Create an Article via the Reporter object::
Create an Article via the Reporter object:
.. code-block:: pycon
>>> new_article = r.article_set.create(headline="John's second story", pub_date=date(2005, 7, 29))
>>> new_article
@ -77,7 +85,9 @@ Create an Article via the Reporter object::
>>> new_article.reporter.id
1
Create a new article::
Create a new article:
.. code-block:: pycon
>>> new_article2 = Article.objects.create(headline="Paul's story", pub_date=date(2006, 1, 17), reporter=r)
>>> new_article2.reporter
@ -87,7 +97,9 @@ Create a new article::
>>> r.article_set.all()
<QuerySet [<Article: John's second story>, <Article: Paul's story>, <Article: This is a test>]>
Add the same article to a different article set - check that it moves::
Add the same article to a different article set - check that it moves:
.. code-block:: pycon
>>> r2.article_set.add(new_article2)
>>> new_article2.reporter.id
@ -95,7 +107,9 @@ Add the same article to a different article set - check that it moves::
>>> new_article2.reporter
<Reporter: Paul Jones>
Adding an object of the wrong type raises TypeError::
Adding an object of the wrong type raises TypeError:
.. code-block:: pycon
>>> r.article_set.add(r2)
Traceback (most recent call last):
@ -118,7 +132,9 @@ Note that in the last example the article has moved from John to Paul.
Related managers support field lookups as well.
The API automatically follows relationships as far as you need.
Use double underscores to separate relationships.
This works as many levels deep as you want. There's no limit. For example::
This works as many levels deep as you want. There's no limit. For example:
.. code-block:: pycon
>>> r.article_set.filter(headline__startswith='This')
<QuerySet [<Article: This is a test>]>
@ -127,19 +143,25 @@ This works as many levels deep as you want. There's no limit. For example::
>>> Article.objects.filter(reporter__first_name='John')
<QuerySet [<Article: John's second story>, <Article: This is a test>]>
Exact match is implied here::
Exact match is implied here:
.. code-block:: pycon
>>> Article.objects.filter(reporter__first_name='John')
<QuerySet [<Article: John's second story>, <Article: This is a test>]>
Query twice over the related field. This translates to an AND condition in the
WHERE clause::
WHERE clause:
.. code-block:: pycon
>>> Article.objects.filter(reporter__first_name='John', reporter__last_name='Smith')
<QuerySet [<Article: John's second story>, <Article: This is a test>]>
For the related lookup you can supply a primary key value or pass the related
object explicitly::
object explicitly:
.. code-block:: pycon
>>> Article.objects.filter(reporter__pk=1)
<QuerySet [<Article: John's second story>, <Article: This is a test>]>
@ -153,12 +175,16 @@ object explicitly::
>>> Article.objects.filter(reporter__in=[r,r2]).distinct()
<QuerySet [<Article: John's second story>, <Article: Paul's story>, <Article: This is a test>]>
You can also use a queryset instead of a literal list of instances::
You can also use a queryset instead of a literal list of instances:
.. code-block:: pycon
>>> Article.objects.filter(reporter__in=Reporter.objects.filter(first_name='John')).distinct()
<QuerySet [<Article: John's second story>, <Article: This is a test>]>
Querying in the opposite direction::
Querying in the opposite direction:
.. code-block:: pycon
>>> Reporter.objects.filter(article__pk=1)
<QuerySet [<Reporter: John Smith>]>
@ -172,14 +198,18 @@ Querying in the opposite direction::
>>> Reporter.objects.filter(article__headline__startswith='This').distinct()
<QuerySet [<Reporter: John Smith>]>
Counting in the opposite direction works in conjunction with ``distinct()``::
Counting in the opposite direction works in conjunction with ``distinct()``:
.. code-block:: pycon
>>> Reporter.objects.filter(article__headline__startswith='This').count()
3
>>> Reporter.objects.filter(article__headline__startswith='This').distinct().count()
1
Queries can go round in circles::
Queries can go round in circles:
.. code-block:: pycon
>>> Reporter.objects.filter(article__reporter__first_name__startswith='John')
<QuerySet [<Reporter: John Smith>, <Reporter: John Smith>, <Reporter: John Smith>, <Reporter: John Smith>]>
@ -190,7 +220,9 @@ Queries can go round in circles::
If you delete a reporter, their articles will be deleted (assuming that the
ForeignKey was defined with :attr:`django.db.models.ForeignKey.on_delete` set to
``CASCADE``, which is the default)::
``CASCADE``, which is the default):
.. code-block:: pycon
>>> Article.objects.all()
<QuerySet [<Article: John's second story>, <Article: Paul's story>, <Article: This is a test>]>
@ -202,7 +234,9 @@ ForeignKey was defined with :attr:`django.db.models.ForeignKey.on_delete` set to
>>> Reporter.objects.order_by('first_name')
<QuerySet [<Reporter: John Smith>]>
You can delete using a JOIN in the query::
You can delete using a JOIN in the query:
.. code-block:: pycon
>>> Reporter.objects.filter(article__headline__startswith='This').delete()
>>> Reporter.objects.all()

View File

@ -38,31 +38,39 @@ In this example, a ``Place`` optionally can be a ``Restaurant``::
What follows are examples of operations that can be performed using the Python
API facilities.
.. highlight:: pycon
Create a couple of Places:
Create a couple of Places::
.. code-block:: pycon
>>> p1 = Place(name='Demon Dogs', address='944 W. Fullerton')
>>> p1.save()
>>> p2 = Place(name='Ace Hardware', address='1013 N. Ashland')
>>> p2.save()
Create a Restaurant. Pass the "parent" object as this object's primary key::
Create a Restaurant. Pass the "parent" object as this object's primary key:
.. code-block:: pycon
>>> r = Restaurant(place=p1, serves_hot_dogs=True, serves_pizza=False)
>>> r.save()
A Restaurant can access its place::
A Restaurant can access its place:
.. code-block:: pycon
>>> r.place
<Place: Demon Dogs the place>
A Place can access its restaurant, if available::
A Place can access its restaurant, if available:
.. code-block:: pycon
>>> p1.restaurant
<Restaurant: Demon Dogs the restaurant>
p2 doesn't have an associated restaurant::
p2 doesn't have an associated restaurant:
.. code-block:: pycon
>>> from django.core.exceptions import ObjectDoesNotExist
>>> try:
@ -71,13 +79,17 @@ p2 doesn't have an associated restaurant::
>>> print("There is no restaurant here.")
There is no restaurant here.
You can also use ``hasattr`` to avoid the need for exception catching::
You can also use ``hasattr`` to avoid the need for exception catching:
.. code-block:: pycon
>>> hasattr(p2, 'restaurant')
False
Set the place using assignment notation. Because place is the primary key on
Restaurant, the save will create a new restaurant::
Restaurant, the save will create a new restaurant:
.. code-block:: pycon
>>> r.place = p2
>>> r.save()
@ -86,7 +98,9 @@ Restaurant, the save will create a new restaurant::
>>> r.place
<Place: Ace Hardware the place>
Set the place back again, using assignment in the reverse direction::
Set the place back again, using assignment in the reverse direction:
.. code-block:: pycon
>>> p1.restaurant = r
>>> p1.restaurant
@ -94,7 +108,9 @@ Set the place back again, using assignment in the reverse direction::
Note that you must save an object before it can be assigned to a one-to-one
relationship. For example, creating a ``Restaurant`` with unsaved ``Place``
raises ``ValueError``::
raises ``ValueError``:
.. code-block:: pycon
>>> p3 = Place(name='Demon Dogs', address='944 W. Fullerton')
>>> Restaurant.objects.create(place=p3, serves_hot_dogs=True, serves_pizza=False)
@ -104,18 +120,24 @@ raises ``ValueError``::
Restaurant.objects.all() returns the Restaurants, not the Places. Note that
there are two restaurants - Ace Hardware the Restaurant was created in the call
to r.place = p2::
to r.place = p2:
.. code-block:: pycon
>>> Restaurant.objects.all()
<QuerySet [<Restaurant: Demon Dogs the restaurant>, <Restaurant: Ace Hardware the restaurant>]>
Place.objects.all() returns all Places, regardless of whether they have
Restaurants::
Restaurants:
.. code-block:: pycon
>>> Place.objects.order_by('name')
<QuerySet [<Place: Ace Hardware the place>, <Place: Demon Dogs the place>]>
You can query the models using :ref:`lookups across relationships <lookups-that-span-relationships>`::
You can query the models using :ref:`lookups across relationships <lookups-that-span-relationships>`:
.. code-block:: pycon
>>> Restaurant.objects.get(place=p1)
<Restaurant: Demon Dogs the restaurant>
@ -126,7 +148,9 @@ You can query the models using :ref:`lookups across relationships <lookups-that-
>>> Restaurant.objects.exclude(place__address__contains="Ashland")
<QuerySet [<Restaurant: Demon Dogs the restaurant>]>
This also works in reverse::
This also works in reverse:
.. code-block:: pycon
>>> Place.objects.get(pk=1)
<Place: Demon Dogs the place>
@ -140,20 +164,26 @@ This also works in reverse::
If you delete a place, its restaurant will be deleted (assuming that the
``OneToOneField`` was defined with
:attr:`~django.db.models.ForeignKey.on_delete` set to ``CASCADE``, which is the
default)::
default):
.. code-block:: pycon
>>> p2.delete()
(2, {'one_to_one.Restaurant': 1, 'one_to_one.Place': 1})
>>> Restaurant.objects.all()
<QuerySet [<Restaurant: Demon Dogs the restaurant>]>
Add a Waiter to the Restaurant::
Add a Waiter to the Restaurant:
.. code-block:: pycon
>>> w = r.waiter_set.create(name='Joe')
>>> w
<Waiter: Joe the waiter at Demon Dogs the restaurant>
Query the waiters::
Query the waiters:
.. code-block:: pycon
>>> Waiter.objects.filter(restaurant__place=p1)
<QuerySet [<Waiter: Joe the waiter at Demon Dogs the restaurant>]>

View File

@ -43,7 +43,9 @@ Django will load any and all fixtures it finds in these locations that match
the provided fixture names.
If the named fixture has a file extension, only fixtures of that type
will be loaded. For example::
will be loaded. For example:
.. code-block:: shell
django-admin loaddata mydata.json
@ -52,7 +54,9 @@ must correspond to the registered name of a
:ref:`serializer <serialization-formats>` (e.g., ``json`` or ``xml``).
If you omit the extensions, Django will search all available fixture types
for a matching fixture. For example::
for a matching fixture. For example:
.. code-block:: shell
django-admin loaddata mydata
@ -61,7 +65,9 @@ directory contained ``mydata.json``, that fixture would be loaded
as a JSON fixture.
The fixtures that are named can include directory components. These
directories will be included in the search path. For example::
directories will be included in the search path. For example:
.. code-block:: shell
django-admin loaddata foo/bar/mydata.json
@ -124,7 +130,9 @@ Compressed fixtures
===================
Fixtures may be compressed in ``zip``, ``gz``, ``bz2``, ``lzma``, or ``xz``
format. For example::
format. For example:
.. code-block:: shell
django-admin loaddata mydata.json

View File

@ -425,7 +425,9 @@ Implementation concerns
Whatever features you add to your custom ``Manager``, it must be
possible to make a shallow copy of a ``Manager`` instance; i.e., the
following code must work::
following code must work:
.. code-block:: pycon
>>> import copy
>>> manager = MyManager()

View File

@ -189,7 +189,7 @@ ones:
name = models.CharField(max_length=60)
shirt_size = models.CharField(max_length=1, choices=SHIRT_SIZES)
::
.. code-block:: pycon
>>> p = Person(name="Fred Flintstone", shirt_size="L")
>>> p.save()
@ -503,7 +503,9 @@ There are a few restrictions on the intermediate model:
Now that you have set up your :class:`~django.db.models.ManyToManyField` to use
your intermediary model (``Membership``, in this case), you're ready to start
creating some many-to-many relationships. You do this by creating instances of
the intermediate model::
the intermediate model:
.. code-block:: pycon
>>> ringo = Person.objects.create(name="Ringo Starr")
>>> paul = Person.objects.create(name="Paul McCartney")
@ -526,7 +528,9 @@ You can also use :meth:`~django.db.models.fields.related.RelatedManager.add`,
:meth:`~django.db.models.fields.related.RelatedManager.create`, or
:meth:`~django.db.models.fields.related.RelatedManager.set` to create
relationships, as long as you specify ``through_defaults`` for any required
fields::
fields:
.. code-block:: pycon
>>> beatles.members.add(john, through_defaults={'date_joined': date(1960, 8, 1)})
>>> beatles.members.create(name="George Harrison", through_defaults={'date_joined': date(1960, 8, 1)})
@ -537,7 +541,9 @@ You may prefer to create instances of the intermediate model directly.
If the custom through table defined by the intermediate model does not enforce
uniqueness on the ``(model1, model2)`` pair, allowing multiple values, the
:meth:`~django.db.models.fields.related.RelatedManager.remove` call will
remove all intermediate model instances::
remove all intermediate model instances:
.. code-block:: pycon
>>> Membership.objects.create(person=ringo, group=beatles,
... date_joined=date(1968, 9, 4),
@ -550,7 +556,9 @@ remove all intermediate model instances::
<QuerySet [<Person: Paul McCartney>]>
The :meth:`~django.db.models.fields.related.RelatedManager.clear`
method can be used to remove all many-to-many relationships for an instance::
method can be used to remove all many-to-many relationships for an instance:
.. code-block:: pycon
>>> # Beatles have broken up
>>> beatles.members.clear()
@ -560,13 +568,17 @@ method can be used to remove all many-to-many relationships for an instance::
Once you have established the many-to-many relationships, you can issue
queries. Just as with normal many-to-many relationships, you can query using
the attributes of the many-to-many-related model::
the attributes of the many-to-many-related model:
.. code-block:: pycon
# Find all the groups with a member whose name starts with 'Paul'
>>> Group.objects.filter(members__name__startswith='Paul')
<QuerySet [<Group: The Beatles>]>
As you are using an intermediate model, you can also query on its attributes::
As you are using an intermediate model, you can also query on its attributes:
.. code-block:: pycon
# Find all the members of the Beatles that joined after 1 Jan 1961
>>> Person.objects.filter(
@ -575,7 +587,9 @@ As you are using an intermediate model, you can also query on its attributes::
<QuerySet [<Person: Ringo Starr]>
If you need to access a membership's information you may do so by directly
querying the ``Membership`` model::
querying the ``Membership`` model:
.. code-block:: pycon
>>> ringos_membership = Membership.objects.get(group=beatles, person=ringo)
>>> ringos_membership.date_joined
@ -585,7 +599,9 @@ querying the ``Membership`` model::
Another way to access the same information is by querying the
:ref:`many-to-many reverse relationship<m2m-reverse-relationships>` from a
``Person`` object::
``Person`` object:
.. code-block:: pycon
>>> ringos_membership = ringo.membership_set.get(group=beatles)
>>> ringos_membership.date_joined
@ -1120,14 +1136,18 @@ For example::
All of the fields of ``Place`` will also be available in ``Restaurant``,
although the data will reside in a different database table. So these are both
possible::
possible:
.. code-block:: pycon
>>> Place.objects.filter(name="Bob's Cafe")
>>> Restaurant.objects.filter(name="Bob's Cafe")
If you have a ``Place`` that is also a ``Restaurant``, you can get from the
``Place`` object to the ``Restaurant`` object by using the lowercase version of
the model name::
the model name:
.. code-block:: pycon
>>> p = Place.objects.get(id=12)
# If p is a Restaurant object, this will give the child class:
@ -1264,7 +1284,9 @@ For example, suppose you want to add a method to the ``Person`` model. You can d
The ``MyPerson`` class operates on the same database table as its parent
``Person`` class. In particular, any new instances of ``Person`` will also be
accessible through ``MyPerson``, and vice-versa::
accessible through ``MyPerson``, and vice-versa:
.. code-block:: pycon
>>> p = Person.objects.create(first_name="foobar")
>>> MyPerson.objects.get(first_name="foobar")

View File

@ -85,7 +85,9 @@ The :djadmin:`migrate` management command operates on one database at a
time. By default, it operates on the ``default`` database, but by
providing the :option:`--database <migrate --database>` option, you can tell it
to synchronize a different database. So, to synchronize all models onto
all databases in the first example above, you would need to call::
all databases in the first example above, you would need to call:
.. code-block:: shell
$ ./manage.py migrate
$ ./manage.py migrate --database=users
@ -97,7 +99,9 @@ constraining the availability of particular models.
If, as in the second example above, you've left the ``default`` database empty,
you must provide a database name each time you run :djadmin:`migrate`. Omitting
the database name would raise an error. For the second example::
the database name would raise an error. For the second example:
.. code-block:: shell
$ ./manage.py migrate --database=users
$ ./manage.py migrate --database=customers
@ -405,7 +409,9 @@ catch-all nature of the PrimaryReplicaRouter implementation would mean
that all models would be available on all databases.
With this setup installed, and all databases migrated as per
:ref:`synchronizing_multiple_databases`, lets run some Django code::
:ref:`synchronizing_multiple_databases`, lets run some Django code:
.. code-block:: pycon
>>> # This retrieval will be performed on the 'auth_db' database
>>> fred = User.objects.get(username='fred')
@ -453,7 +459,9 @@ You can select the database for a ``QuerySet`` at any point in the
``QuerySet`` that uses the specified database.
``using()`` takes a single argument: the alias of the database on
which you want to run the query. For example::
which you want to run the query. For example:
.. code-block:: pycon
>>> # This will run on the 'default' database.
>>> Author.objects.all()
@ -471,7 +479,9 @@ Use the ``using`` keyword to ``Model.save()`` to specify to which
database the data should be saved.
For example, to save an object to the ``legacy_users`` database, you'd
use this::
use this:
.. code-block:: pycon
>>> my_object.save(using='legacy_users')
@ -486,7 +496,9 @@ use ``save(using=...)`` as a way to migrate the instance to a new
database. However, if you don't take appropriate steps, this could
have some unexpected consequences.
Consider the following example::
Consider the following example:
.. code-block:: pycon
>>> p = Person(name='Fred')
>>> p.save(using='first') # (statement 1)
@ -510,7 +522,9 @@ will be overridden when ``p`` is saved.
You can avoid this in two ways. First, you can clear the primary key
of the instance. If an object has no primary key, Django will treat it
as a new object, avoiding any loss of data on the ``second``
database::
database:
.. code-block:: pycon
>>> p = Person(name='Fred')
>>> p.save(using='first')
@ -518,7 +532,9 @@ database::
>>> p.save(using='second') # Write a completely new object.
The second option is to use the ``force_insert`` option to ``save()``
to ensure that Django does an SQL ``INSERT``::
to ensure that Django does an SQL ``INSERT``:
.. code-block:: pycon
>>> p = Person(name='Fred')
>>> p.save(using='first')
@ -534,7 +550,9 @@ Selecting a database to delete from
By default, a call to delete an existing object will be executed on
the same database that was used to retrieve the object in the first
place::
place:
.. code-block:: pycon
>>> u = User.objects.using('legacy_users').get(username='fred')
>>> u.delete() # will delete from the `legacy_users` database
@ -544,7 +562,9 @@ To specify the database from which a model will be deleted, pass a
argument works just like the ``using`` keyword argument to ``save()``.
For example, if you're migrating a user from the ``legacy_users``
database to the ``new_users`` database, you might use these commands::
database to the ``new_users`` database, you might use these commands:
.. code-block:: pycon
>>> user_obj.save(using='new_users')
>>> user_obj.delete(using='legacy_users')

View File

@ -82,13 +82,17 @@ Understand cached attributes
As well as caching of the whole ``QuerySet``, there is caching of the result of
attributes on ORM objects. In general, attributes that are not callable will be
cached. For example, assuming the :ref:`example blog models
<queryset-model-example>`::
<queryset-model-example>`:
.. code-block:: pycon
>>> entry = Entry.objects.get(id=1)
>>> entry.blog # Blog object is retrieved at this point
>>> entry.blog # cached version, no DB access
But in general, callable attributes cause DB lookups every time::
But in general, callable attributes cause DB lookups every time:
.. code-block:: pycon
>>> entry = Entry.objects.get(id=1)
>>> entry.authors.all() # query performed
@ -164,18 +168,24 @@ First, the query will be quicker because of the underlying database index.
Also, the query could run much slower if multiple objects match the lookup;
having a unique constraint on the column guarantees this will never happen.
So using the :ref:`example blog models <queryset-model-example>`::
So using the :ref:`example blog models <queryset-model-example>`:
.. code-block:: pycon
>>> entry = Entry.objects.get(id=10)
will be quicker than:
.. code-block:: pycon
>>> entry = Entry.objects.get(headline="News Item Title")
because ``id`` is indexed by the database and is guaranteed to be unique.
Doing the following is potentially quite slow:
.. code-block:: pycon
>>> entry = Entry.objects.get(headline__startswith="News")
First of all, ``headline`` is not indexed, which will make the underlying

View File

@ -59,7 +59,9 @@ class represents a particular record in the database table.
To create an object, instantiate it using keyword arguments to the model class,
then call :meth:`~django.db.models.Model.save` to save it to the database.
Assuming models live in a file ``mysite/blog/models.py``, here's an example::
Assuming models live in a file ``mysite/blog/models.py``, here's an example:
.. code-block:: pycon
>>> from blog.models import Blog
>>> b = Blog(name='Beatles Blog', tagline='All the latest Beatles news.')
@ -86,7 +88,9 @@ To save changes to an object that's already in the database, use
:meth:`~django.db.models.Model.save`.
Given a ``Blog`` instance ``b5`` that has already been saved to the database,
this example changes its name and updates its record in the database::
this example changes its name and updates its record in the database:
.. code-block:: pycon
>>> b5.name = 'New name'
>>> b5.save()
@ -101,7 +105,9 @@ Updating a :class:`~django.db.models.ForeignKey` field works exactly the same
way as saving a normal field -- assign an object of the right type to the field
in question. This example updates the ``blog`` attribute of an ``Entry``
instance ``entry``, assuming appropriate instances of ``Entry`` and ``Blog``
are already saved to the database (so we can retrieve them below)::
are already saved to the database (so we can retrieve them below):
.. code-block:: pycon
>>> from blog.models import Blog, Entry
>>> entry = Entry.objects.get(pk=1)
@ -113,7 +119,9 @@ Updating a :class:`~django.db.models.ManyToManyField` works a little
differently -- use the
:meth:`~django.db.models.fields.related.RelatedManager.add` method on the field
to add a record to the relation. This example adds the ``Author`` instance
``joe`` to the ``entry`` object::
``joe`` to the ``entry`` object:
.. code-block:: pycon
>>> from blog.models import Author
>>> joe = Author.objects.create(name="Joe")
@ -121,7 +129,9 @@ to add a record to the relation. This example adds the ``Author`` instance
To add multiple records to a :class:`~django.db.models.ManyToManyField` in one
go, include multiple arguments in the call to
:meth:`~django.db.models.fields.related.RelatedManager.add`, like this::
:meth:`~django.db.models.fields.related.RelatedManager.add`, like this:
.. code-block:: pycon
>>> john = Author.objects.create(name="John")
>>> paul = Author.objects.create(name="Paul")
@ -150,7 +160,9 @@ You get a :class:`~django.db.models.query.QuerySet` by using your model's
:class:`~django.db.models.Manager`. Each model has at least one
:class:`~django.db.models.Manager`, and it's called
:attr:`~django.db.models.Model.objects` by default. Access it directly via the
model class, like so::
model class, like so:
.. code-block:: pycon
>>> Blog.objects
<django.db.models.manager.Manager object at ...>
@ -176,7 +188,9 @@ Retrieving all objects
The simplest way to retrieve objects from a table is to get all of them. To do
this, use the :meth:`~django.db.models.query.QuerySet.all` method on a
:class:`~django.db.models.Manager`::
:class:`~django.db.models.Manager`:
.. code-block:: pycon
>>> all_entries = Entry.objects.all()
@ -223,7 +237,9 @@ Chaining filters
The result of refining a :class:`~django.db.models.query.QuerySet` is itself a
:class:`~django.db.models.query.QuerySet`, so it's possible to chain
refinements together. For example::
refinements together. For example:
.. code-block:: pycon
>>> Entry.objects.filter(
... headline__startswith='What'
@ -250,7 +266,9 @@ the previous :class:`~django.db.models.query.QuerySet`. Each refinement creates
a separate and distinct :class:`~django.db.models.query.QuerySet` that can be
stored, used and reused.
Example::
Example:
.. code-block:: pycon
>>> q1 = Entry.objects.filter(headline__startswith="What")
>>> q2 = q1.exclude(pub_date__gte=datetime.date.today())
@ -274,7 +292,9 @@ refinement process.
:class:`~django.db.models.query.QuerySet` doesn't involve any database
activity. You can stack filters together all day long, and Django won't
actually run the query until the :class:`~django.db.models.query.QuerySet` is
*evaluated*. Take a look at this example::
*evaluated*. Take a look at this example:
.. code-block:: pycon
>>> q = Entry.objects.filter(headline__startswith="What")
>>> q = q.filter(pub_date__lte=datetime.date.today())
@ -301,7 +321,9 @@ the query - in this case, it will be a
If you know there is only one object that matches your query, you can use the
:meth:`~django.db.models.query.QuerySet.get` method on a
:class:`~django.db.models.Manager` which returns the object directly::
:class:`~django.db.models.Manager` which returns the object directly:
.. code-block:: pycon
>>> one_entry = Entry.objects.get(pk=1)
@ -345,11 +367,15 @@ Use a subset of Python's array-slicing syntax to limit your
:class:`~django.db.models.query.QuerySet` to a certain number of results. This
is the equivalent of SQL's ``LIMIT`` and ``OFFSET`` clauses.
For example, this returns the first 5 objects (``LIMIT 5``)::
For example, this returns the first 5 objects (``LIMIT 5``):
.. code-block:: pycon
>>> Entry.objects.all()[:5]
This returns the sixth through tenth objects (``OFFSET 5 LIMIT 5``)::
This returns the sixth through tenth objects (``OFFSET 5 LIMIT 5``):
.. code-block:: pycon
>>> Entry.objects.all()[5:10]
@ -359,7 +385,9 @@ Generally, slicing a :class:`~django.db.models.query.QuerySet` returns a new
:class:`~django.db.models.query.QuerySet` -- it doesn't evaluate the query. An
exception is if you use the "step" parameter of Python slice syntax. For
example, this would actually execute the query in order to return a list of
every *second* object of the first 10::
every *second* object of the first 10:
.. code-block:: pycon
>>> Entry.objects.all()[:10:2]
@ -369,11 +397,15 @@ ambiguous nature of how that might work.
To retrieve a *single* object rather than a list
(e.g. ``SELECT foo FROM bar LIMIT 1``), use an index instead of a slice. For
example, this returns the first ``Entry`` in the database, after ordering
entries alphabetically by headline::
entries alphabetically by headline:
.. code-block:: pycon
>>> Entry.objects.order_by('headline')[0]
This is roughly equivalent to::
This is roughly equivalent to:
.. code-block:: pycon
>>> Entry.objects.order_by('headline')[0:1].get()
@ -393,7 +425,9 @@ methods :meth:`~django.db.models.query.QuerySet.filter`,
:meth:`~django.db.models.query.QuerySet.get`.
Basic lookups keyword arguments take the form ``field__lookuptype=value``.
(That's a double-underscore). For example::
(That's a double-underscore). For example:
.. code-block:: pycon
>>> Entry.objects.filter(pub_date__lte='2006-01-01')
@ -426,7 +460,9 @@ a taste of what's available, here's some of the more common lookups you'll
probably use:
:lookup:`exact`
An "exact" match. For example::
An "exact" match. For example:
.. code-block:: pycon
>>> Entry.objects.get(headline__exact="Cat bites dog")
@ -440,7 +476,9 @@ probably use:
doesn't contain a double underscore -- the lookup type is assumed to be
``exact``.
For example, the following two statements are equivalent::
For example, the following two statements are equivalent:
.. code-block:: pycon
>>> Blog.objects.get(id__exact=14) # Explicit form
>>> Blog.objects.get(id=14) # __exact is implied
@ -448,7 +486,9 @@ probably use:
This is for convenience, because ``exact`` lookups are the common case.
:lookup:`iexact`
A case-insensitive match. So, the query::
A case-insensitive match. So, the query:
.. code-block:: pycon
>>> Blog.objects.get(name__iexact="beatles blog")
@ -491,7 +531,9 @@ across models, separated by double underscores, until you get to the field you
want.
This example retrieves all ``Entry`` objects with a ``Blog`` whose ``name``
is ``'Beatles Blog'``::
is ``'Beatles Blog'``:
.. code-block:: pycon
>>> Entry.objects.filter(blog__name='Beatles Blog')
@ -502,7 +544,9 @@ It works backwards, too. While it :attr:`can be customized
relationship in a lookup using the lowercase name of the model.
This example retrieves all ``Blog`` objects which have at least one ``Entry``
whose ``headline`` contains ``'Lennon'``::
whose ``headline`` contains ``'Lennon'``:
.. code-block:: pycon
>>> Blog.objects.filter(entry__headline__contains='Lennon')
@ -649,7 +693,9 @@ of two different fields on the same model instance.
For example, to find a list of all blog entries that have had more comments
than pingbacks, we construct an ``F()`` object to reference the pingback count,
and use that ``F()`` object in the query::
and use that ``F()`` object in the query:
.. code-block:: pycon
>>> from django.db.models import F
>>> Entry.objects.filter(number_of_comments__gt=F('number_of_pingbacks'))
@ -657,13 +703,17 @@ and use that ``F()`` object in the query::
Django supports the use of addition, subtraction, multiplication,
division, modulo, and power arithmetic with ``F()`` objects, both with constants
and with other ``F()`` objects. To find all the blog entries with more than
*twice* as many comments as pingbacks, we modify the query::
*twice* as many comments as pingbacks, we modify the query:
.. code-block:: pycon
>>> Entry.objects.filter(number_of_comments__gt=F('number_of_pingbacks') * 2)
To find all the entries where the rating of the entry is less than the
sum of the pingback count and comment count, we would issue the
query::
query:
.. code-block:: pycon
>>> Entry.objects.filter(rating__lt=F('number_of_comments') + F('number_of_pingbacks'))
@ -671,19 +721,25 @@ You can also use the double underscore notation to span relationships in
an ``F()`` object. An ``F()`` object with a double underscore will introduce
any joins needed to access the related object. For example, to retrieve all
the entries where the author's name is the same as the blog name, we could
issue the query::
issue the query:
.. code-block:: pycon
>>> Entry.objects.filter(authors__name=F('blog__name'))
For date and date/time fields, you can add or subtract a
:class:`~datetime.timedelta` object. The following would return all entries
that were modified more than 3 days after they were published::
that were modified more than 3 days after they were published:
.. code-block:: pycon
>>> from datetime import timedelta
>>> Entry.objects.filter(mod_date__gt=F('pub_date') + timedelta(days=3))
The ``F()`` objects support bitwise operations by ``.bitand()``, ``.bitor()``,
``.bitxor()``, ``.bitrightshift()``, and ``.bitleftshift()``. For example::
``.bitxor()``, ``.bitrightshift()``, and ``.bitleftshift()``. For example:
.. code-block:: pycon
>>> F('somefield').bitand(16)
@ -699,18 +755,24 @@ Expressions can reference transforms
Django supports using transforms in expressions.
For example, to find all ``Entry`` objects published in the same year as they
were last modified::
were last modified:
.. code-block:: pycon
>>> from django.db.models import F
>>> Entry.objects.filter(pub_date__year=F('mod_date__year'))
To find the earliest year an entry was published, we can issue the query::
To find the earliest year an entry was published, we can issue the query:
.. code-block:: pycon
>>> from django.db.models import Min
>>> Entry.objects.aggregate(first_published_year=Min('pub_date__year'))
This example finds the value of the highest rated entry and the total number
of comments on all entries for each year::
of comments on all entries for each year:
.. code-block:: pycon
>>> from django.db.models import OuterRef, Subquery, Sum
>>> Entry.objects.values('pub_date__year').annotate(
@ -729,14 +791,18 @@ For convenience, Django provides a ``pk`` lookup shortcut, which stands for
"primary key".
In the example ``Blog`` model, the primary key is the ``id`` field, so these
three statements are equivalent::
three statements are equivalent:
.. code-block:: pycon
>>> Blog.objects.get(id__exact=14) # Explicit form
>>> Blog.objects.get(id=14) # __exact is implied
>>> Blog.objects.get(pk=14) # pk implies id__exact
The use of ``pk`` isn't limited to ``__exact`` queries -- any query term
can be combined with ``pk`` to perform a query on the primary key of a model::
can be combined with ``pk`` to perform a query on the primary key of a model:
.. code-block:: pycon
# Get blogs entries with id 1, 4 and 7
>>> Blog.objects.filter(pk__in=[1,4,7])
@ -745,7 +811,9 @@ can be combined with ``pk`` to perform a query on the primary key of a model::
>>> Blog.objects.filter(pk__gt=14)
``pk`` lookups also work across joins. For example, these three statements are
equivalent::
equivalent:
.. code-block:: pycon
>>> Entry.objects.filter(blog__id__exact=3) # Explicit form
>>> Entry.objects.filter(blog__id=3) # __exact is implied
@ -763,7 +831,9 @@ underscore signifies a single-character wildcard.)
This means things should work intuitively, so the abstraction doesn't leak.
For example, to retrieve all the entries that contain a percent sign, use the
percent sign as any other character::
percent sign as any other character:
.. code-block:: pycon
>>> Entry.objects.filter(headline__contains='%')
@ -798,7 +868,9 @@ results.
Keep this caching behavior in mind, because it may bite you if you don't use
your :class:`~django.db.models.query.QuerySet`\s correctly. For example, the
following will create two :class:`~django.db.models.query.QuerySet`\s, evaluate
them, and throw them away::
them, and throw them away:
.. code-block:: pycon
>>> print([e.headline for e in Entry.objects.all()])
>>> print([e.pub_date for e in Entry.objects.all()])
@ -809,7 +881,9 @@ the same database records, because an ``Entry`` may have been added or deleted
in the split second between the two requests.
To avoid this problem, save the :class:`~django.db.models.query.QuerySet` and
reuse it::
reuse it:
.. code-block:: pycon
>>> queryset = Entry.objects.all()
>>> print([p.headline for p in queryset]) # Evaluate the query set.
@ -825,14 +899,18 @@ returned by the subsequent query are not cached. Specifically, this means that
index will not populate the cache.
For example, repeatedly getting a certain index in a queryset object will query
the database each time::
the database each time:
.. code-block:: pycon
>>> queryset = Entry.objects.all()
>>> print(queryset[5]) # Queries the database
>>> print(queryset[5]) # Queries the database again
However, if the entire queryset has already been evaluated, the cache will be
checked instead::
checked instead:
.. code-block:: pycon
>>> queryset = Entry.objects.all()
>>> [entry for entry in queryset] # Queries the database
@ -840,7 +918,9 @@ checked instead::
>>> print(queryset[5]) # Uses cache
Here are some examples of other actions that will result in the entire queryset
being evaluated and therefore populate the cache::
being evaluated and therefore populate the cache:
.. code-block:: pycon
>>> [entry for entry in queryset]
>>> bool(queryset)
@ -975,7 +1055,9 @@ is inside a :py:class:`list` or :py:class:`dict`, it will always be interpreted
as JSON ``null``.
When querying, ``None`` value will always be interpreted as JSON ``null``. To
query for SQL ``NULL``, use :lookup:`isnull`::
query for SQL ``NULL``, use :lookup:`isnull`:
.. code-block:: pycon
>>> Dog.objects.create(name='Max', data=None) # SQL NULL.
<Dog: Max>
@ -1015,7 +1097,9 @@ Unless you are sure you wish to work with SQL ``NULL`` values, consider setting
Key, index, and path transforms
-------------------------------
To query based on a given dictionary key, use that key as the lookup name::
To query based on a given dictionary key, use that key as the lookup name:
.. code-block:: pycon
>>> Dog.objects.create(name='Rufus', data={
... 'breed': 'labrador',
@ -1032,13 +1116,17 @@ To query based on a given dictionary key, use that key as the lookup name::
>>> Dog.objects.filter(data__breed='collie')
<QuerySet [<Dog: Meg>]>
Multiple keys can be chained together to form a path lookup::
Multiple keys can be chained together to form a path lookup:
.. code-block:: pycon
>>> Dog.objects.filter(data__owner__name='Bob')
<QuerySet [<Dog: Rufus>]>
If the key is an integer, it will be interpreted as an index transform in an
array::
array:
.. code-block:: pycon
>>> Dog.objects.filter(data__owner__other_pets__0__name='Fishy')
<QuerySet [<Dog: Rufus>]>
@ -1046,7 +1134,9 @@ array::
If the key you wish to query by clashes with the name of another lookup, use
the :lookup:`contains <jsonfield.contains>` lookup instead.
To query for missing keys, use the ``isnull`` lookup::
To query for missing keys, use the ``isnull`` lookup:
.. code-block:: pycon
>>> Dog.objects.create(name='Shep', data={'breed': 'collie'})
<Dog: Shep>
@ -1075,7 +1165,9 @@ To query for missing keys, use the ``isnull`` lookup::
:class:`~django.db.models.JSONField`. You can use the double underscore
notation in ``lookup`` to chain dictionary key and index transforms.
For example::
For example:
.. code-block:: pycon
>>> from django.db.models.fields.json import KT
>>> Dog.objects.create(name="Shep", data={
@ -1142,7 +1234,9 @@ Containment and key lookups
The :lookup:`contains` lookup is overridden on ``JSONField``. The returned
objects are those where the given ``dict`` of key-value pairs are all
contained in the top-level of the field. For example::
contained in the top-level of the field. For example:
.. code-block:: pycon
>>> Dog.objects.create(name='Rufus', data={'breed': 'labrador', 'owner': 'Bob'})
<Dog: Rufus>
@ -1166,7 +1260,9 @@ contained in the top-level of the field. For example::
This is the inverse of the :lookup:`contains <jsonfield.contains>` lookup - the
objects returned will be those where the key-value pairs on the object are a
subset of those in the value passed. For example::
subset of those in the value passed. For example:
.. code-block:: pycon
>>> Dog.objects.create(name='Rufus', data={'breed': 'labrador', 'owner': 'Bob'})
<Dog: Rufus>
@ -1189,7 +1285,9 @@ subset of those in the value passed. For example::
~~~~~~~~~~~
Returns objects where the given key is in the top-level of the data. For
example::
example:
.. code-block:: pycon
>>> Dog.objects.create(name='Rufus', data={'breed': 'labrador'})
<Dog: Rufus>
@ -1204,7 +1302,9 @@ example::
~~~~~~~~~~~~
Returns objects where all of the given keys are in the top-level of the data.
For example::
For example:
.. code-block:: pycon
>>> Dog.objects.create(name='Rufus', data={'breed': 'labrador'})
<Dog: Rufus>
@ -1219,7 +1319,9 @@ For example::
~~~~~~~~~~~~~~~~
Returns objects where any of the given keys are in the top-level of the data.
For example::
For example:
.. code-block:: pycon
>>> Dog.objects.create(name='Rufus', data={'breed': 'labrador'})
<Dog: Rufus>
@ -1318,14 +1420,18 @@ To compare two model instances, use the standard Python comparison operator,
the double equals sign: ``==``. Behind the scenes, that compares the primary
key values of two models.
Using the ``Entry`` example above, the following two statements are equivalent::
Using the ``Entry`` example above, the following two statements are equivalent:
.. code-block:: pycon
>>> some_entry == other_entry
>>> some_entry.id == other_entry.id
If a model's primary key isn't called ``id``, no problem. Comparisons will
always use the primary key, whatever it's called. For example, if a model's
primary key field is called ``name``, these two statements are equivalent::
primary key field is called ``name``, these two statements are equivalent:
.. code-block:: pycon
>>> some_obj == other_obj
>>> some_obj.name == other_obj.name
@ -1338,7 +1444,9 @@ Deleting objects
The delete method, conveniently, is named
:meth:`~django.db.models.Model.delete`. This method immediately deletes the
object and returns the number of objects deleted and a dictionary with
the number of deletions per object type. Example::
the number of deletions per object type. Example:
.. code-block:: pycon
>>> e.delete()
(1, {'blog.Entry': 1})
@ -1349,7 +1457,9 @@ You can also delete objects in bulk. Every
members of that :class:`~django.db.models.query.QuerySet`.
For example, this deletes all ``Entry`` objects with a ``pub_date`` year of
2005::
2005:
.. code-block:: pycon
>>> Entry.objects.filter(pub_date__year=2005).delete()
(5, {'webapp.Entry': 5})
@ -1458,7 +1568,9 @@ a :class:`~django.db.models.query.QuerySet`. You can do this with the
You can only set non-relation fields and :class:`~django.db.models.ForeignKey`
fields using this method. To update a non-relation field, provide the new value
as a constant. To update :class:`~django.db.models.ForeignKey` fields, set the
new value to be the new model instance you want to point to. For example::
new value to be the new model instance you want to point to. For example:
.. code-block:: pycon
>>> b = Blog.objects.get(pk=1)
@ -1471,7 +1583,9 @@ some rows already have the new value). The only restriction on the
:class:`~django.db.models.query.QuerySet` being updated is that it can only
access one database table: the model's main table. You can filter based on
related fields, but you can only update columns in the model's main
table. Example::
table. Example:
.. code-block:: pycon
>>> b = Blog.objects.get(pk=1)
@ -1495,14 +1609,18 @@ them and call :meth:`~django.db.models.Model.save`::
Calls to update can also use :class:`F expressions <django.db.models.F>` to
update one field based on the value of another field in the model. This is
especially useful for incrementing counters based upon their current value. For
example, to increment the pingback count for every entry in the blog::
example, to increment the pingback count for every entry in the blog:
.. code-block:: pycon
>>> Entry.objects.update(number_of_pingbacks=F('number_of_pingbacks') + 1)
However, unlike ``F()`` objects in filter and exclude clauses, you can't
introduce joins when you use ``F()`` objects in an update -- you can only
reference fields local to the model being updated. If you attempt to introduce
a join with an ``F()`` object, a ``FieldError`` will be raised::
a join with an ``F()`` object, a ``FieldError`` will be raised:
.. code-block:: pycon
# This will raise a FieldError
>>> Entry.objects.update(headline=F('blog__name'))
@ -1543,14 +1661,18 @@ Forward
If a model has a :class:`~django.db.models.ForeignKey`, instances of that model
will have access to the related (foreign) object via an attribute of the model.
Example::
Example:
.. code-block:: pycon
>>> e = Entry.objects.get(id=2)
>>> e.blog # Returns the related Blog object.
You can get and set via a foreign-key attribute. As you may expect, changes to
the foreign key aren't saved to the database until you call
:meth:`~django.db.models.Model.save`. Example::
:meth:`~django.db.models.Model.save`. Example:
.. code-block:: pycon
>>> e = Entry.objects.get(id=2)
>>> e.blog = some_blog
@ -1558,7 +1680,9 @@ the foreign key aren't saved to the database until you call
If a :class:`~django.db.models.ForeignKey` field has ``null=True`` set (i.e.,
it allows ``NULL`` values), you can assign ``None`` to remove the relation.
Example::
Example:
.. code-block:: pycon
>>> e = Entry.objects.get(id=2)
>>> e.blog = None
@ -1566,7 +1690,9 @@ Example::
Forward access to one-to-many relationships is cached the first time the
related object is accessed. Subsequent accesses to the foreign key on the same
object instance are cached. Example::
object instance are cached. Example:
.. code-block:: pycon
>>> e = Entry.objects.get(id=2)
>>> print(e.blog) # Hits the database to retrieve the associated Blog.
@ -1574,7 +1700,9 @@ object instance are cached. Example::
Note that the :meth:`~django.db.models.query.QuerySet.select_related`
:class:`~django.db.models.query.QuerySet` method recursively prepopulates the
cache of all one-to-many relationships ahead of time. Example::
cache of all one-to-many relationships ahead of time. Example:
.. code-block:: pycon
>>> e = Entry.objects.select_related().get(id=2)
>>> print(e.blog) # Doesn't hit the database; uses cached version.
@ -1593,7 +1721,9 @@ source model name, lowercased. This :class:`~django.db.models.Manager` returns
``QuerySets``, which can be filtered and manipulated as described in the
"Retrieving objects" section above.
Example::
Example:
.. code-block:: pycon
>>> b = Blog.objects.get(id=1)
>>> b.entry_set.all() # Returns all Entry objects related to Blog.
@ -1606,7 +1736,9 @@ You can override the ``FOO_set`` name by setting the
:attr:`~django.db.models.ForeignKey.related_name` parameter in the
:class:`~django.db.models.ForeignKey` definition. For example, if the ``Entry``
model was altered to ``blog = ForeignKey(Blog, on_delete=models.CASCADE,
related_name='entries')``, the above example code would look like this::
related_name='entries')``, the above example code would look like this:
.. code-block:: pycon
>>> b = Blog.objects.get(id=1)
>>> b.entries.all() # Returns all Entry objects related to Blog.

View File

@ -17,7 +17,9 @@ Standard textual queries
------------------------
Text-based fields have a selection of matching operations. For example, you may
wish to allow lookup up an author like so::
wish to allow lookup up an author like so:
.. code-block:: pycon
>>> Author.objects.filter(name__contains='Terry')
[<Author: Terry Gilliam>, <Author: Terry Jones>]
@ -47,7 +49,9 @@ demonstrate the kind of functionality databases may have.
In the above example, we determined that a case insensitive lookup would be
more useful. When dealing with non-English names, a further improvement is to
use :lookup:`unaccented comparison <unaccent>`::
use :lookup:`unaccented comparison <unaccent>`:
.. code-block:: pycon
>>> Author.objects.filter(name__unaccent__icontains='Helen')
[<Author: Helen Mirren>, <Author: Helena Bonham Carter>, <Author: Hélène Joy>]
@ -58,7 +62,9 @@ will pick up ``Helena`` or ``Hélène``, but not the reverse. Another option
would be to use a :lookup:`trigram_similar` comparison, which compares
sequences of letters.
For example::
For example:
.. code-block:: pycon
>>> Author.objects.filter(name__unaccent__lower__trigram_similar='Hélène')
[<Author: Helen Mirren>, <Author: Hélène Joy>]
@ -110,12 +116,16 @@ as categorization.
The :mod:`django.contrib.postgres` module provides some helpers to make these
queries. For example, a query might select all the blog entries which mention
"cheese"::
"cheese":
.. code-block:: pycon
>>> Entry.objects.filter(body_text__search='cheese')
[<Entry: Cheese on Toast recipes>, <Entry: Pizza recipes>]
You can also filter on a combination of fields and on related models::
You can also filter on a combination of fields and on related models:
.. code-block:: pycon
>>> Entry.objects.annotate(
... search=SearchVector('blog__tagline', 'body_text'),

View File

@ -56,7 +56,9 @@ This is best illustrated with an example. Suppose you have the following model::
last_name = models.CharField(...)
birth_date = models.DateField(...)
You could then execute custom SQL like so::
You could then execute custom SQL like so:
.. code-block:: pycon
>>> for p in Person.objects.raw('SELECT * FROM myapp_person'):
... print(p)
@ -104,7 +106,9 @@ Mapping query fields to model fields
``raw()`` automatically maps fields in the query to fields on the model.
The order of fields in your query doesn't matter. In other words, both
of the following queries work identically::
of the following queries work identically:
.. code-block:: pycon
>>> Person.objects.raw('SELECT id, first_name, last_name, birth_date FROM myapp_person')
...
@ -113,7 +117,9 @@ of the following queries work identically::
Matching is done by name. This means that you can use SQL's ``AS`` clauses to
map fields in the query to model fields. So if you had some other table that
had ``Person`` data in it, you could easily map it into ``Person`` instances::
had ``Person`` data in it, you could easily map it into ``Person`` instances:
.. code-block:: pycon
>>> Person.objects.raw('''SELECT first AS first_name,
... last AS last_name,
@ -126,7 +132,9 @@ As long as the names match, the model instances will be created correctly.
Alternatively, you can map fields in the query to model fields using the
``translations`` argument to ``raw()``. This is a dictionary mapping names of
fields in the query to names of fields on the model. For example, the above
query could also be written::
query could also be written:
.. code-block:: pycon
>>> name_map = {'first': 'first_name', 'last': 'last_name', 'bd': 'birth_date', 'pk': 'id'}
>>> Person.objects.raw('SELECT * FROM some_other_table', translations=name_map)
@ -135,26 +143,34 @@ Index lookups
-------------
``raw()`` supports indexing, so if you need only the first result you can
write::
write:
.. code-block:: pycon
>>> first_person = Person.objects.raw('SELECT * FROM myapp_person')[0]
However, the indexing and slicing are not performed at the database level. If
you have a large number of ``Person`` objects in your database, it is more
efficient to limit the query at the SQL level::
efficient to limit the query at the SQL level:
.. code-block:: pycon
>>> first_person = Person.objects.raw('SELECT * FROM myapp_person LIMIT 1')[0]
Deferring model fields
----------------------
Fields may also be left out::
Fields may also be left out:
.. code-block:: pycon
>>> people = Person.objects.raw('SELECT id, first_name FROM myapp_person')
The ``Person`` objects returned by this query will be deferred model instances
(see :meth:`~django.db.models.query.QuerySet.defer()`). This means that the
fields that are omitted from the query will be loaded on demand. For example::
fields that are omitted from the query will be loaded on demand. For example:
.. code-block:: pycon
>>> for p in Person.objects.raw('SELECT id, first_name FROM myapp_person'):
... print(p.first_name, # This will be retrieved by the original query
@ -179,7 +195,9 @@ Adding annotations
You can also execute queries containing fields that aren't defined on the
model. For example, we could use `PostgreSQL's age() function`__ to get a list
of people with their ages calculated by the database::
of people with their ages calculated by the database:
.. code-block:: pycon
>>> people = Person.objects.raw('SELECT *, age(birth_date) AS age FROM myapp_person')
>>> for p in people:
@ -197,7 +215,9 @@ Passing parameters into ``raw()``
---------------------------------
If you need to perform parameterized queries, you can use the ``params``
argument to ``raw()``::
argument to ``raw()``:
.. code-block:: pycon
>>> lname = 'Doe'
>>> Person.objects.raw('SELECT * FROM myapp_person WHERE last_name = %s', [lname])
@ -218,13 +238,17 @@ replaced with parameters from the ``params`` argument.
**Do not use string formatting on raw queries or quote placeholders in your
SQL strings!**
It's tempting to write the above query as::
It's tempting to write the above query as:
.. code-block:: pycon
>>> query = 'SELECT * FROM myapp_person WHERE last_name = %s' % lname
>>> Person.objects.raw(query)
You might also think you should write your query like this (with quotes
around ``%s``)::
around ``%s``):
.. code-block:: pycon
>>> query = "SELECT * FROM myapp_person WHERE last_name = '%s'"
@ -313,7 +337,9 @@ immutable and accessible by field names or indices, which might be useful::
nt_result = namedtuple('Result', [col[0] for col in desc])
return [nt_result(*row) for row in cursor.fetchall()]
Here is an example of the difference between the three::
Here is an example of the difference between the three:
.. code-block:: pycon
>>> cursor.execute("SELECT id, parent_id FROM test LIMIT 2")
>>> cursor.fetchall()

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