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django/docs/howto/initial-data.txt
Tobias Kunze 4a954cfd11 Fixed #30573 -- Rephrased documentation to avoid words that minimise the involved difficulty.
This patch does not remove all occurrences of the words in question.
Rather, I went through all of the occurrences of the words listed
below, and judged if they a) suggested the reader had some kind of
knowledge/experience, and b) if they added anything of value (including
tone of voice, etc). I left most of the words alone. I looked at the
following words:

- simply/simple
- easy/easier/easiest
- obvious
- just
- merely
- straightforward
- ridiculous

Thanks to Carlton Gibson for guidance on how to approach this issue, and
to Tim Bell for providing the idea. But the enormous lion's share of
thanks go to Adam Johnson for his patient and helpful review.
2019-09-06 13:27:46 +02:00

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=================================
Providing initial data for models
=================================
It's sometimes useful to pre-populate your database with hard-coded data when
you're first setting up an app. You can provide initial data with migrations or
fixtures.
Providing initial data with migrations
======================================
If you want to automatically load initial data for an app, create a
:ref:`data migration <data-migrations>`. Migrations are run when setting up the
test database, so the data will be available there, subject to :ref:`some
limitations <test-case-serialized-rollback>`.
.. _initial-data-via-fixtures:
Providing data with fixtures
============================
You can also provide data using fixtures, however, this data isn't loaded
automatically, except if you use :attr:`.TransactionTestCase.fixtures`.
A fixture is a collection of data that Django knows how to import into a
database. The most straightforward way of creating a fixture if you've already
got some data is to use the :djadmin:`manage.py dumpdata <dumpdata>` command.
Or, you can write fixtures by hand; fixtures can be written as JSON, XML or YAML
(with PyYAML_ installed) documents. The :doc:`serialization documentation
</topics/serialization>` has more details about each of these supported
:ref:`serialization formats <serialization-formats>`.
.. _PyYAML: https://pyyaml.org/
As an example, though, here's what a fixture for a ``Person`` model might look
like in JSON:
.. code-block:: js
[
{
"model": "myapp.person",
"pk": 1,
"fields": {
"first_name": "John",
"last_name": "Lennon"
}
},
{
"model": "myapp.person",
"pk": 2,
"fields": {
"first_name": "Paul",
"last_name": "McCartney"
}
}
]
And here's that same fixture as YAML:
.. code-block:: yaml
- model: myapp.person
pk: 1
fields:
first_name: John
last_name: Lennon
- model: myapp.person
pk: 2
fields:
first_name: Paul
last_name: McCartney
You'll store this data in a ``fixtures`` directory inside your app.
You can load data by calling :djadmin:`manage.py loaddata <loaddata>`
``<fixturename>``, where ``<fixturename>`` is the name of the fixture file
you've created. Each time you run :djadmin:`loaddata`, the data will be read
from the fixture and re-loaded into the database. Note this means that if you
change one of the rows created by a fixture and then run :djadmin:`loaddata`
again, you'll wipe out any changes you've made.
Where Django finds fixture files
--------------------------------
By default, Django looks in the ``fixtures`` directory inside each app for
fixtures. You can set the :setting:`FIXTURE_DIRS` setting to a list of
additional directories where Django should look.
When running :djadmin:`manage.py loaddata <loaddata>`, you can also
specify a path to a fixture file, which overrides searching the usual
directories.
.. seealso::
Fixtures are also used by the :ref:`testing framework
<topics-testing-fixtures>` to help set up a consistent test environment.