django/docs/ref/contrib/flatpages.txt

=================
The flatpages app
=================

.. module:: django.contrib.flatpages
   :synopsis: A framework for managing simple ?flat? HTML content in a database.

Django comes with an optional "flatpages" application. It lets you store simple
"flat" HTML content in a database and handles the management for you via
Django's admin interface and a Python API.

A flatpage is a simple object with a URL, title and content. Use it for
one-off, special-case pages, such as "About" or "Privacy Policy" pages, that
you want to store in a database but for which you don't want to develop a
custom Django application.

A flatpage can use a custom template or a default, systemwide flatpage
template. It can be associated with one, or multiple, sites.

The content field may optionally be left blank if you prefer to put your
content in a custom template.

Here are some examples of flatpages on Django-powered sites:

* http://www.lawrence.com/about/contact/
* http://www2.ljworld.com/site/rules/

Installation
============

To install the flatpages app, follow these steps:

1. Install the :mod:`sites framework <django.contrib.sites>` by adding
   ``'django.contrib.sites'`` to your :setting:`INSTALLED_APPS` setting,
   if it's not already in there.

   Also make sure you've correctly set :setting:`SITE_ID` to the ID of the
   site the settings file represents. This will usually be ``1`` (i.e.
   ``SITE_ID = 1``, but if you're using the sites framework to manage
   multiple sites, it could be the ID of a different site.

2. Add ``'django.contrib.flatpages'`` to your :setting:`INSTALLED_APPS`
   setting.

Then either:

3. Add an entry in your URLconf. For example::

    urlpatterns = [
        path('pages/', include('django.contrib.flatpages.urls')),
    ]

or:

3. Add ``'django.contrib.flatpages.middleware.FlatpageFallbackMiddleware'``
   to your :setting:`MIDDLEWARE` setting.

4. Run the command :djadmin:`manage.py migrate <migrate>`.

.. currentmodule:: django.contrib.flatpages.middleware

How it works
============

``manage.py migrate`` creates two tables in your database: ``django_flatpage``
and ``django_flatpage_sites``. ``django_flatpage`` is a simple lookup table
that simply maps a URL to a title and bunch of text content.
``django_flatpage_sites`` associates a flatpage with a site.

Using the URLconf
-----------------

There are several ways to include the flat pages in your URLconf. You can
dedicate a particular path to flat pages::

    urlpatterns = [
        path('pages/', include('django.contrib.flatpages.urls')),
    ]

You can also set it up as a "catchall" pattern. In this case, it is important
to place the pattern at the end of the other urlpatterns::

    from django.contrib.flatpages import views

    # Your other patterns here
    urlpatterns += [
        path('<path:url>', views.flatpage),
    ]

.. warning::

    If you set :setting:`APPEND_SLASH` to ``False``, you must remove the slash
    in the catchall pattern or flatpages without a trailing slash will not be
    matched.

Another common setup is to use flat pages for a limited set of known pages and
to hard code the urls, so you can reference them with the :ttag:`url` template
tag::

    from django.contrib.flatpages import views

    urlpatterns += [
        path('about-us/', views.flatpage, {'url': '/about-us/'}, name='about'),
        path('license/', views.flatpage, {'url': '/license/'}, name='license'),
    ]

Using the middleware
--------------------

The :class:`~django.contrib.flatpages.middleware.FlatpageFallbackMiddleware`
can do all of the work.

.. class:: FlatpageFallbackMiddleware

    Each time any Django application raises a 404 error, this middleware
    checks the flatpages database for the requested URL as a last resort.
    Specifically, it checks for a flatpage with the given URL with a site ID
    that corresponds to the :setting:`SITE_ID` setting.

    If it finds a match, it follows this algorithm:

    * If the flatpage has a custom template, it loads that template.
      Otherwise, it loads the template :file:`flatpages/default.html`.

    * It passes that template a single context variable, ``flatpage``,
      which is the flatpage object. It uses
      :class:`~django.template.RequestContext` in rendering the
      template.

    The middleware will only add a trailing slash and redirect (by looking
    at the :setting:`APPEND_SLASH` setting) if the resulting URL refers to
    a valid flatpage. Redirects are permanent (301 status code).

    If it doesn't find a match, the request continues to be processed as usual.

    The middleware only gets activated for 404s -- not for 500s or responses
    of any other status code.

.. admonition:: Flatpages will not apply view middleware

   Because the ``FlatpageFallbackMiddleware`` is applied only after
   URL resolution has failed and produced a 404, the response it
   returns will not apply any :ref:`view middleware <view-middleware>`
   methods. Only requests which are successfully routed to a view via
   normal URL resolution apply view middleware.

Note that the order of :setting:`MIDDLEWARE` matters. Generally, you can put
:class:`~django.contrib.flatpages.middleware.FlatpageFallbackMiddleware` at the
end of the list. This means it will run first when processing the response, and
ensures that any other response-processing middleware see the real flatpage
response rather than the 404.

For more on middleware, read the :doc:`middleware docs
</topics/http/middleware>`.

.. admonition:: Ensure that your 404 template works

    Note that the
    :class:`~django.contrib.flatpages.middleware.FlatpageFallbackMiddleware`
    only steps in once another view has successfully produced a 404 response.
    If another view or middleware class attempts to produce a 404 but ends up
    raising an exception instead, the response will become an HTTP 500
    ("Internal Server Error") and the
    :class:`~django.contrib.flatpages.middleware.FlatpageFallbackMiddleware`
    will not attempt to serve a flat page.

.. currentmodule:: django.contrib.flatpages.models

How to add, change and delete flatpages
=======================================

.. _flatpages-admin:

Via the admin interface
-----------------------

If you've activated the automatic Django admin interface, you should see a
"Flatpages" section on the admin index page. Edit flatpages as you edit any
other object in the system.

The ``FlatPage`` model has an ``enable_comments`` field that isn't used by
``contrib.flatpages``, but that could be useful for your project or third-party
apps. It doesn't appear in the admin interface, but you can add it by
registering a custom ``ModelAdmin`` for ``FlatPage``::

    from django.contrib import admin
    from django.contrib.flatpages.admin import FlatPageAdmin
    from django.contrib.flatpages.models import FlatPage
    from django.utils.translation import gettext_lazy as _

    # Define a new FlatPageAdmin
    class FlatPageAdmin(FlatPageAdmin):
        fieldsets = (
            (None, {'fields': ('url', 'title', 'content', 'sites')}),
            (_('Advanced options'), {
                'classes': ('collapse', ),
                'fields': (
                    'enable_comments',
                    'registration_required',
                    'template_name',
                ),
            }),
        )

    # Re-register FlatPageAdmin
    admin.site.unregister(FlatPage)
    admin.site.register(FlatPage, FlatPageAdmin)

Via the Python API
------------------

.. class:: FlatPage

    Flatpages are represented by a standard
    :doc:`Django model </topics/db/models>`,
    which lives in `django/contrib/flatpages/models.py`_. You can access
    flatpage objects via the :doc:`Django database API </topics/db/queries>`.

.. _django/contrib/flatpages/models.py: https://github.com/django/django/blob/master/django/contrib/flatpages/models.py

.. currentmodule:: django.contrib.flatpages

.. admonition:: Check for duplicate flatpage URLs.

    If you add or modify flatpages via your own code, you will likely want to
    check for duplicate flatpage URLs within the same site. The flatpage form
    used in the admin performs this validation check, and can be imported from
    ``django.contrib.flatpages.forms.FlatpageForm`` and used in your own
    views.

Flatpage templates
==================

By default, flatpages are rendered via the template
:file:`flatpages/default.html`, but you can override that for a
particular flatpage: in the admin, a collapsed fieldset titled
"Advanced options" (clicking will expand it) contains a field for
specifying a template name. If you're creating a flat page via the
Python API you can simply set the template name as the field
``template_name`` on the ``FlatPage`` object.

Creating the :file:`flatpages/default.html` template is your responsibility;
in your template directory, just create a :file:`flatpages` directory
containing a file :file:`default.html`.

Flatpage templates are passed a single context variable, ``flatpage``,
which is the flatpage object.

Here's a sample :file:`flatpages/default.html` template:

.. code-block:: html+django

    <!DOCTYPE html>
    <html>
    <head>
    <title>{{ flatpage.title }}</title>
    </head>
    <body>
    {{ flatpage.content }}
    </body>
    </html>

Since you're already entering raw HTML into the admin page for a flatpage,
both ``flatpage.title`` and ``flatpage.content`` are marked as **not**
requiring :ref:`automatic HTML escaping <automatic-html-escaping>` in the
template.

Getting a list of :class:`~django.contrib.flatpages.models.FlatPage` objects in your templates
==============================================================================================

The flatpages app provides a template tag that allows you to iterate
over all of the available flatpages on the :ref:`current site
<hooking-into-current-site-from-views>`.

Like all custom template tags, you'll need to :ref:`load its custom
tag library <loading-custom-template-libraries>` before you can use
it. After loading the library, you can retrieve all current flatpages
via the :ttag:`get_flatpages` tag:

.. code-block:: html+django

    {% load flatpages %}
    {% get_flatpages as flatpages %}
    <ul>
        {% for page in flatpages %}
            <li><a href="{{ page.url }}">{{ page.title }}</a></li>
        {% endfor %}
    </ul>

.. templatetag:: get_flatpages

Displaying ``registration_required`` flatpages
----------------------------------------------

By default, the :ttag:`get_flatpages` templatetag will only show
flatpages that are marked ``registration_required = False``. If you
want to display registration-protected flatpages, you need to specify
an authenticated user using a ``for`` clause.

For example:

.. code-block:: html+django

    {% get_flatpages for someuser as about_pages %}

If you provide an anonymous user, :ttag:`get_flatpages` will behave
the same as if you hadn't provided a user -- i.e., it will only show you
public flatpages.

Limiting flatpages by base URL
------------------------------

An optional argument, ``starts_with``, can be applied to limit the
returned pages to those beginning with a particular base URL. This
argument may be passed as a string, or as a variable to be resolved
from the context.

For example:

.. code-block:: html+django

    {% get_flatpages '/about/' as about_pages %}
    {% get_flatpages about_prefix as about_pages %}
    {% get_flatpages '/about/' for someuser as about_pages %}

Integrating with :mod:`django.contrib.sitemaps`
===============================================

.. currentmodule:: django.contrib.flatpages.sitemaps

.. class:: FlatPageSitemap

    The :class:`sitemaps.FlatPageSitemap
    <django.contrib.flatpages.sitemaps.FlatPageSitemap>` class looks at all
    publicly visible :mod:`~django.contrib.flatpages` defined for the current
    :setting:`SITE_ID` (see the :mod:`sites documentation
    <django.contrib.sites>`) and creates an entry in the sitemap. These entries
    include only the :attr:`~django.contrib.sitemaps.Sitemap.location`
    attribute -- not :attr:`~django.contrib.sitemaps.Sitemap.lastmod`,
    :attr:`~django.contrib.sitemaps.Sitemap.changefreq` or
    :attr:`~django.contrib.sitemaps.Sitemap.priority`.

Example
-------

Here's an example of a URLconf using :class:`FlatPageSitemap`::

    from django.contrib.flatpages.sitemaps import FlatPageSitemap
    from django.contrib.sitemaps.views import sitemap
    from django.urls import path

    urlpatterns = [
        # ...

        # the sitemap
        path('sitemap.xml', sitemap,
            {'sitemaps': {'flatpages': FlatPageSitemap}},
            name='django.contrib.sitemaps.views.sitemap'),
    ]