========================
Django 1.8 release notes
========================

*April 1, 2015*

Welcome to Django 1.8!

These release notes cover the `new features`_, as well as some `backwards
incompatible changes`_ you'll want to be aware of when upgrading from Django
1.7 or older versions. We've also `begun the deprecation process for some
features`_, and some features have reached the end of their deprecation process
and `have been removed`_.

Django 1.8 has been designated as Django's second :term:`long-term support
release`. It will receive security updates for at least three years after its
release. Support for the previous LTS, Django 1.4, will end 6 months from the
release date of Django 1.8.

.. _`new features`: `What's new in Django 1.8`_
.. _`backwards incompatible changes`: `Backwards incompatible changes in 1.8`_
.. _`begun the deprecation process for some features`: `Features deprecated in 1.8`_
.. _`have been removed`: `Features removed in 1.8`_

Python compatibility
====================

Like Django 1.7, Django 1.8 requires Python 2.7 or above, though we
**highly recommend** the latest minor release.

What's new in Django 1.8
========================

``Model._meta`` API
~~~~~~~~~~~~~~~~~~~

Django now has a formalized API for :doc:`Model._meta </ref/models/meta>`,
providing an officially supported way to :ref:`retrieve fields
<model-meta-field-api>` and filter fields based on their :ref:`attributes
<model-field-attributes>`.

The ``Model._meta`` object has been part of Django since the days of pre-0.96
"Magic Removal" -- it just wasn't an official, stable API. In recognition of
this, we've endeavored to maintain backwards-compatibility with the old
API endpoint where possible. However, API endpoints that aren't part of the
new official API have been deprecated and will eventually be removed. A
:ref:`guide to migrating from the old API to the new API
<migrating-old-meta-api>` has been provided.

Multiple template engines
~~~~~~~~~~~~~~~~~~~~~~~~~

Django 1.8 defines a stable API for integrating template backends. It includes
built-in support for the Django template language and for
:class:`~django.template.backends.jinja2.Jinja2`. It supports rendering
templates with multiple engines within the same project. Learn more about the
new features in the :doc:`topic guide </topics/templates>` and check the
:doc:`upgrade instructions </ref/templates/upgrading>` for details.

Security enhancements
~~~~~~~~~~~~~~~~~~~~~

Several features of the django-secure_ third-party library have been
integrated into Django. :class:`django.middleware.security.SecurityMiddleware`
provides several security enhancements to the request/response cycle. The new
:djadminopt:`--deploy` option of the :djadmin:`check` command allows you to
check your production settings file for ways to increase the security of your
site.

.. _django-secure: https://pypi.python.org/pypi/django-secure

New PostgreSQL specific functionality
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Django now has a module with extensions for PostgreSQL specific features, such
as :class:`~django.contrib.postgres.fields.ArrayField`,
:class:`~django.contrib.postgres.fields.HStoreField`, :ref:`range-fields`, and
:lookup:`unaccent` lookup. A full breakdown of the features is available
:doc:`in the documentation </ref/contrib/postgres/index>`.

New data types
~~~~~~~~~~~~~~

* Django now has a :class:`~django.db.models.UUIDField` for storing
  universally unique identifiers. It is stored as the native ``uuid`` data type
  on PostgreSQL and as a fixed length character field on other backends. There
  is a corresponding :class:`form field <django.forms.UUIDField>`.

* Django now has a :class:`~django.db.models.DurationField` for storing periods
  of time - modeled in Python by :class:`~python:datetime.timedelta`. It is
  stored in the native ``interval`` data type on PostgreSQL, as a ``INTERVAL
  DAY(9) TO SECOND(6)`` on Oracle, and as a ``bigint`` of microseconds on other
  backends. Date and time related arithmetic has also been improved on all
  backends. There is a corresponding :class:`form field
  <django.forms.DurationField>`.

Query Expressions, Conditional Expressions, and Database Functions
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

:doc:`Query Expressions </ref/models/expressions>` allow you to create,
customize, and compose complex SQL expressions. This has enabled annotate
to accept expressions other than aggregates. Aggregates are now able to
reference multiple fields, as well as perform arithmetic, similar to ``F()``
objects. :meth:`~django.db.models.query.QuerySet.order_by` has also gained the
ability to accept expressions.

:doc:`Conditional Expressions </ref/models/conditional-expressions>` allow
you to use :keyword:`if` ... :keyword:`elif` ... :keyword:`else` logic within
queries.

A collection of :doc:`database functions </ref/models/database-functions>` is
also included with functionality such as
:class:`~django.db.models.functions.Coalesce`,
:class:`~django.db.models.functions.Concat`, and
:class:`~django.db.models.functions.Substr`.

``TestCase`` data setup
~~~~~~~~~~~~~~~~~~~~~~~

:class:`~django.test.TestCase` has been refactored to allow for data
initialization at the class level using transactions and savepoints. Database
backends which do not support transactions, like MySQL with the MyISAM storage
engine, will still be able to run these tests but won't benefit from the
improvements. Tests are now run within two nested
:func:`~django.db.transaction.atomic()` blocks: one for the whole class and one
for each test.

* The class method
  :meth:`TestCase.setUpTestData() <django.test.TestCase.setUpTestData>` adds
  the ability to setup test data at the class level. Using this technique can
  speed up the tests as compared to using ``setUp()``.

* Fixture loading within ``TestCase`` is now performed once for the whole
  ``TestCase``.

Minor features
~~~~~~~~~~~~~~

:mod:`django.contrib.admin`
^^^^^^^^^^^^^^^^^^^^^^^^^^^

* :class:`~django.contrib.admin.ModelAdmin` now has a
  :meth:`~django.contrib.admin.ModelAdmin.has_module_permission`
  method to allow limiting access to the module on the admin index page.

* :class:`~django.contrib.admin.InlineModelAdmin` now has an attribute
  :attr:`~django.contrib.admin.InlineModelAdmin.show_change_link` that
  supports showing a link to an inline object's change form.

* Use the new ``django.contrib.admin.RelatedOnlyFieldListFilter`` in
  :attr:`ModelAdmin.list_filter <django.contrib.admin.ModelAdmin.list_filter>`
  to limit the ``list_filter`` choices to foreign objects which are attached to
  those from the ``ModelAdmin``.

* The :meth:`ModelAdmin.delete_view()
  <django.contrib.admin.ModelAdmin.delete_view>` displays a summary of objects
  to be deleted on the deletion confirmation page.

* The jQuery library embedded in the admin has been upgraded to version 1.11.2.

* You can now specify :attr:`AdminSite.site_url
  <django.contrib.admin.AdminSite.site_url>` in order to display a link to the
  front-end site.

* You can now specify :attr:`ModelAdmin.show_full_result_count
  <django.contrib.admin.ModelAdmin.show_full_result_count>` to control whether
  or not the full count of objects should be displayed on a filtered admin page.

* The ``AdminSite.password_change()`` method now has an ``extra_context``
  parameter.

* You can now control who may login to the admin site by overriding only
  :meth:`AdminSite.has_permission()
  <django.contrib.admin.AdminSite.has_permission>` and
  :attr:`AdminSite.login_form <django.contrib.admin.AdminSite.login_form>`.
  The ``base.html`` template has a new block ``usertools`` which contains the
  user-specific header. A new context variable ``has_permission``, which gets
  its value from :meth:`~django.contrib.admin.AdminSite.has_permission`,
  indicates whether the user may access the site.

* Foreign key dropdowns now have buttons for changing or deleting related
  objects using a popup.

:mod:`django.contrib.admindocs`
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

* reStructuredText is now parsed in model docstrings.

:mod:`django.contrib.auth`
^^^^^^^^^^^^^^^^^^^^^^^^^^

* Authorization backends can now raise
  :class:`~django.core.exceptions.PermissionDenied` in
  :meth:`~django.contrib.auth.models.User.has_perm`
  and :meth:`~django.contrib.auth.models.User.has_module_perms`
  to short-circuit permission checking.
* :class:`~django.contrib.auth.forms.PasswordResetForm` now
  has a method :meth:`~django.contrib.auth.forms.PasswordResetForm.send_email`
  that can be overridden to customize the mail to be sent.

* The ``max_length`` of :attr:`Permission.name
  <django.contrib.auth.models.Permission.name>` has been increased from 50 to
  255 characters. Please run the database migration.

* :attr:`~django.contrib.auth.models.CustomUser.USERNAME_FIELD` and
  :attr:`~django.contrib.auth.models.CustomUser.REQUIRED_FIELDS` now supports
  :class:`~django.db.models.ForeignKey`\s.

* The default iteration count for the PBKDF2 password hasher has been
  increased by 33%. This backwards compatible change will not affect users who
  have subclassed ``django.contrib.auth.hashers.PBKDF2PasswordHasher`` to
  change the default value.

:mod:`django.contrib.gis`
^^^^^^^^^^^^^^^^^^^^^^^^^^

* A new :doc:`GeoJSON serializer </ref/contrib/gis/serializers>` is now
  available.

* It is now allowed to include a subquery as a geographic lookup argument, for
  example ``City.objects.filter(point__within=Country.objects.filter(continent='Africa').values('mpoly'))``.

* The Spatialite backend now supports ``Collect`` and ``Extent`` aggregates
  when the database version is 3.0 or later.

* The PostGIS 2 ``CREATE EXTENSION postgis`` and the Spatialite
  ``SELECT InitSpatialMetaData`` initialization commands are now automatically
  run by :djadmin:`migrate`.

* The GDAL interface now supports retrieving properties of
  :ref:`raster (image) data file <raster-data-source-objects>`.

* Compatibility shims for ``SpatialRefSys`` and ``GeometryColumns`` changed in
  Django 1.2 have been removed.

* All GDAL-related exceptions are now raised with ``GDALException``. The former
  ``OGRException`` has been kept for backwards compatibility but should not be
  used any longer.

:mod:`django.contrib.sessions`
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

* Session cookie is now deleted after
  :meth:`~django.contrib.sessions.backends.base.SessionBase.flush()` is called.

:mod:`django.contrib.sitemaps`
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

* The new :attr:`Sitemap.i18n <django.contrib.sitemaps.Sitemap.i18n>` attribute
  allows you to generate a sitemap based on the :setting:`LANGUAGES` setting.

:mod:`django.contrib.sites`
^^^^^^^^^^^^^^^^^^^^^^^^^^^

* :func:`~django.contrib.sites.shortcuts.get_current_site` will now lookup
  the current site based on :meth:`request.get_host()
  <django.http.HttpRequest.get_host>` if the :setting:`SITE_ID` setting is not
  defined.

* The default :class:`~django.contrib.sites.models.Site` created when running
  ``migrate`` now respects the :setting:`SITE_ID` setting (instead of always
  using ``pk=1``).

Cache
^^^^^

* The ``incr()`` method of the
  ``django.core.cache.backends.locmem.LocMemCache`` backend is now thread-safe.

Cryptography
^^^^^^^^^^^^

* The ``max_age`` parameter of the
  :meth:`django.core.signing.TimestampSigner.unsign` method now also accepts a
  :py:class:`datetime.timedelta` object.

Database backends
^^^^^^^^^^^^^^^^^

* The MySQL backend no longer strips microseconds from ``datetime`` values as
  MySQL 5.6.4 and up supports fractional seconds depending on the declaration
  of the datetime field (when ``DATETIME`` includes fractional precision greater
  than 0). New datetime database columns created with Django 1.8 and MySQL 5.6.4
  and up will support microseconds. See the :ref:`MySQL database notes
  <mysql-fractional-seconds>` for more details.

* The MySQL backend no longer creates explicit indexes for foreign keys when
  using the InnoDB storage engine, as MySQL already creates them automatically.

* The Oracle backend no longer defines the ``connection_persists_old_columns``
  feature as ``True``. Instead, Oracle will now include a cache busting clause
  when getting the description of a table.

Email
^^^^^

* :ref:`Email backends <topic-email-backends>` now support the context manager
  protocol for opening and closing connections.

* The SMTP email backend now supports ``keyfile`` and ``certfile``
  authentication with the :setting:`EMAIL_SSL_CERTFILE` and
  :setting:`EMAIL_SSL_KEYFILE` settings.

* The SMTP :class:`~django.core.mail.backends.smtp.EmailBackend` now supports
  setting the ``timeout`` parameter with the :setting:`EMAIL_TIMEOUT` setting.

* :class:`~django.core.mail.EmailMessage` and ``EmailMultiAlternatives`` now
  support the ``reply_to`` parameter.

File Storage
^^^^^^^^^^^^

* :meth:`Storage.get_available_name()
  <django.core.files.storage.Storage.get_available_name>` and
  :meth:`Storage.save() <django.core.files.storage.Storage.save>`
  now take a ``max_length`` argument to implement storage-level maximum
  filename length constraints. Filenames exceeding this argument will get
  truncated. This prevents a database error when appending a unique suffix to a
  long filename that already exists on the storage. See the :ref:`deprecation
  note <storage-max-length-update>` about adding this argument to your custom
  storage classes.

Forms
^^^^^

* Form widgets now render attributes with a value of ``True`` or ``False``
  as HTML5 boolean attributes.

* The new :meth:`~django.forms.Form.has_error()` method allows checking
  if a specific error has happened.

* If :attr:`~django.forms.Form.required_css_class` is defined on a form, then
  the ``<label>`` tags for required fields will have this class present in its
  attributes.

* The rendering of non-field errors in unordered lists (``<ul>``) now includes
  ``nonfield`` in its list of classes to distinguish them from field-specific
  errors.

* :class:`~django.forms.Field` now accepts a
  :attr:`~django.forms.Field.label_suffix` argument, which will override the
  form's :attr:`~django.forms.Form.label_suffix`. This enables customizing the
  suffix on a per-field basis — previously it wasn't possible to override
  a form's :attr:`~django.forms.Form.label_suffix` while using  shortcuts such
  as ``{{ form.as_p }}`` in templates.

* :class:`~django.forms.SelectDateWidget` now accepts an
  :attr:`~django.forms.SelectDateWidget.empty_label` argument, which will
  override the top list choice label when :class:`~django.forms.DateField`
  is not required.

* After an :class:`~django.forms.ImageField` has been cleaned and validated, the
  ``UploadedFile`` object will have an additional ``image`` attribute containing
  the Pillow ``Image`` instance used to check if the file was a valid image. It
  will also update ``UploadedFile.content_type`` with the image's content type
  as determined by Pillow.

* You can now pass a callable that returns an iterable of choices when
  instantiating a :class:`~django.forms.ChoiceField`.

Generic Views
^^^^^^^^^^^^^

* Generic views that use :class:`~django.views.generic.list.MultipleObjectMixin`
  may now specify the ordering applied to the
  :attr:`~django.views.generic.list.MultipleObjectMixin.queryset` by setting
  :attr:`~django.views.generic.list.MultipleObjectMixin.ordering` or overriding
  :meth:`~django.views.generic.list.MultipleObjectMixin.get_ordering()`.

* The new :attr:`SingleObjectMixin.query_pk_and_slug
  <django.views.generic.detail.SingleObjectMixin.query_pk_and_slug>`
  attribute allows changing the behavior of
  :meth:`~django.views.generic.detail.SingleObjectMixin.get_object()`
  so that it'll perform its lookup using both the primary key and the slug.

* The :meth:`~django.views.generic.edit.FormMixin.get_form()` method doesn't
  require a ``form_class`` to be provided anymore. If not provided ``form_class``
  defaults to :meth:`~django.views.generic.edit.FormMixin.get_form_class()`.

* Placeholders in :attr:`ModelFormMixin.success_url
  <django.views.generic.edit.ModelFormMixin.success_url>` now support the Python
  :py:meth:`str.format()` syntax. The legacy ``%(<foo>)s`` syntax is still
  supported but will be removed in Django 1.10.

Internationalization
^^^^^^^^^^^^^^^^^^^^

* :setting:`FORMAT_MODULE_PATH` can now be a list of strings representing
  module paths. This allows importing several format modules from different
  reusable apps. It also allows overriding those custom formats in your main
  Django project.

Logging
^^^^^^^

* The :class:`django.utils.log.AdminEmailHandler` class now has a
  :meth:`~django.utils.log.AdminEmailHandler.send_mail` method to make it more
  subclass friendly.

Management Commands
^^^^^^^^^^^^^^^^^^^

* Database connections are now always closed after a management command called
  from the command line has finished doing its job.

* Commands from alternate package formats like eggs are now also discovered.

* :djadmin:`dumpdata` now has the option :djadminopt:`--output` which allows
  specifying the file to which the serialized data is written.

* :djadmin:`makemessages` and :djadmin:`compilemessages` now have the option
  :djadminopt:`--exclude` which allows exclusion of specific locales from
  processing.

* :djadmin:`compilemessages` now has a ``--use-fuzzy`` or ``-f`` option which
  includes fuzzy translations into compiled files.

* The :djadminopt:`--ignorenonexistent` option of the :djadmin:`loaddata`
  management command now ignores data for models that no longer exist.

* :djadmin:`runserver` now uses daemon threads for faster reloading.

* :djadmin:`inspectdb` now outputs ``Meta.unique_together``. It is also able to
  introspect :class:`~django.db.models.AutoField` for MySQL and PostgreSQL
  databases.

* When calling management commands from code through :ref:`call_command
  <call-command>` and passing options, the option name can match the command
  line option name (without the initial dashes) or the final option destination
  variable name, but in either case, the resulting option received by the
  command is now always the ``dest`` name specified in the command option
  definition (as long as the command uses the new :py:mod:`argparse` module).

* The :djadmin:`dbshell` command now supports MySQL's optional SSL certificate
  authority setting (``--ssl-ca``).

* The :djadminopt:`--name` option for :djadmin:`makemigrations` allows you to
  to give the migration(s) a custom name instead of a generated one.

* The :djadmin:`loaddata` command now prevents repeated fixture loading. If
  :setting:`FIXTURE_DIRS` contains duplicates or a default fixture directory
  path (``app_name/fixtures``), an exception is raised.

* :djadmin:`makemigrations` now supports an :djadminopt:`--exit` option to
  exit with an error code if no migrations are created.

* The new :djadmin:`showmigrations` command allows listing all migrations and
  their dependencies in a project.

Middleware
^^^^^^^^^^

* The :attr:`CommonMiddleware.response_redirect_class
  <django.middleware.common.CommonMiddleware.response_redirect_class>`
  attribute allows you to customize the redirects issued by the middleware.

* A debug message will be logged to the ``django.request`` logger when a
  middleware raises a :exc:`~django.core.exceptions.MiddlewareNotUsed` exception
  in :setting:`DEBUG` mode.

Migrations
^^^^^^^^^^

* The :class:`~django.db.migrations.operations.RunSQL` operation can now handle
  parameters passed to the SQL statements.

* It is now possible to have migrations (most probably :ref:`data migrations
  <data-migrations>`) for applications without models.

* Migrations can now :ref:`serialize model managers
  <using-managers-in-migrations>` as part of the model state.

* A :ref:`generic mechanism to handle the deprecation of model fields
  <migrations-removing-model-fields>` was added.

* The :meth:`RunPython.noop() <django.db.migrations.operations.RunPython.noop>`
  and :attr:`RunSQL.noop <django.db.migrations.operations.RunSQL.noop>` class
  method/attribute were added to ease in making ``RunPython`` and ``RunSQL``
  operations reversible.

* The migration operations :class:`~django.db.migrations.operations.RunPython`
  and :class:`~django.db.migrations.operations.RunSQL` now call the
  :meth:`allow_migrate` method of database routers. The router can use the
  newly introduced ``app_label`` and ``hints`` arguments to make a routing
  decision. To take advantage of this feature you need to update the router to
  the new ``allow_migrate`` signature, see the :ref:`deprecation section
  <deprecated-signature-of-allow-migrate>` for more details.

Models
^^^^^^

* Django now logs at most 9000 queries in ``connections.queries``, in order
  to prevent excessive memory usage in long-running processes in debug mode.

* There is now a model ``Meta`` option to define a
  :attr:`default related name <django.db.models.Options.default_related_name>`
  for all relational fields of a model.

* Pickling models and querysets across different versions of Django isn't
  officially supported (it may work, but there's no guarantee). An extra
  variable that specifies the current Django version is now added to the
  pickled state of models and querysets, and Django raises a ``RuntimeWarning``
  when these objects are unpickled in a different version than the one in
  which they were pickled.

* Added :meth:`Model.from_db() <django.db.models.Model.from_db()>` which
  Django uses whenever objects are loaded using the ORM. The method allows
  customizing model loading behavior.

* ``extra(select={...})`` now allows you to escape a literal ``%s`` sequence
  using ``%%s``.

* :doc:`Custom Lookups</howto/custom-lookups>` can now be registered using
  a decorator pattern.

* The new :attr:`Transform.bilateral <django.db.models.Transform.bilateral>`
  attribute allows creating bilateral transformations. These transformations
  are applied to both ``lhs`` and ``rhs`` when used in a lookup expression,
  providing opportunities for more sophisticated lookups.

* SQL special characters (\, %, _) are now escaped properly when a pattern
  lookup (e.g. ``contains``, ``startswith``, etc.) is used with an ``F()``
  expression as the right-hand side. In those cases, the escaping is performed
  by the database, which can lead to somewhat complex queries involving nested
  ``REPLACE`` function calls.

* You can now refresh model instances by using :meth:`Model.refresh_from_db()
  <django.db.models.Model.refresh_from_db>`.

* You can now get the set of deferred fields for a model using
  :meth:`Model.get_deferred_fields() <django.db.models.Model.get_deferred_fields>`.

* Model field ``default``’s are now used when primary key field's are set to
  ``None``.

Signals
^^^^^^^

* Exceptions from the ``(receiver, exception)`` tuples returned by
  :meth:`Signal.send_robust() <django.dispatch.Signal.send_robust>` now have
  their traceback attached as a ``__traceback__`` attribute.

* The ``environ`` argument, which contains the WSGI environment structure from
  the request, was added to the :data:`~django.core.signals.request_started`
  signal.

* You can now import the :func:`~django.test.signals.setting_changed` signal
  from ``django.core.signals`` to avoid loading ``django.test`` in non-test
  situations. Django no longer does so itself.

System Check Framework
^^^^^^^^^^^^^^^^^^^^^^

* :attr:`~django.core.checks.register` can now be used as a function.

Templates
^^^^^^^^^

* :tfilter:`urlize` now supports domain-only links that include characters after
  the top-level domain (e.g. ``djangoproject.com/`` and
  ``djangoproject.com/download/``).

* :tfilter:`urlize` doesn't treat exclamation marks at the end of a domain or
  its query string as part of the URL (the URL in e.g. ``'djangoproject.com!``
  is ``djangoproject.com``)

* Added a :class:`locmem.Loader <django.template.loaders.locmem.Loader>`
  class that loads Django templates from a Python dictionary.

* The :ttag:`now` tag can now store its output in a context variable with the
  usual syntax: ``{% now 'j n Y' as varname %}``.

Requests and Responses
^^^^^^^^^^^^^^^^^^^^^^

* ``WSGIRequest`` now respects paths starting with ``//``.

* The :meth:`HttpRequest.build_absolute_uri()
  <django.http.HttpRequest.build_absolute_uri>` method now handles paths
  starting with ``//`` correctly.

* If :setting:`DEBUG` is ``True`` and a request raises a
  :exc:`~django.core.exceptions.SuspiciousOperation`, the response will be
  rendered with a detailed error page.

* The ``query_string`` argument of :class:`~django.http.QueryDict` is now
  optional, defaulting to ``None``, so a blank ``QueryDict`` can now be
  instantiated with ``QueryDict()`` instead of ``QueryDict(None)`` or
  ``QueryDict('')``.

* The ``GET`` and ``POST`` attributes of an :class:`~django.http.HttpRequest`
  object are now :class:`~django.http.QueryDict`\s rather than dictionaries,
  and the ``FILES`` attribute is now a ``MultiValueDict``.
  This brings this class into line with the documentation and with
  ``WSGIRequest``.

* The :attr:`HttpResponse.charset <django.http.HttpResponse.charset>` attribute
  was added.

* ``WSGIRequestHandler`` now follows RFC in converting URI to IRI, using
  ``uri_to_iri()``.

* The :meth:`HttpRequest.get_full_path()
  <django.http.HttpRequest.get_full_path>` method now escapes unsafe characters
  from the path portion of a Uniform Resource Identifier (URI) properly.

* :class:`~django.http.HttpResponse` now implements a few additional methods
  like :meth:`~django.http.HttpResponse.getvalue` so that instances can be used
  as stream objects.

* The new :meth:`HttpResponse.setdefault()
  <django.http.HttpResponse.setdefault>` method allows setting a header unless
  it has already been set.

* You can use the new :class:`~django.http.FileResponse` to stream files.

* The :func:`~django.views.decorators.http.condition` decorator for
  conditional view processing now supports the ``If-unmodified-since`` header.

Tests
^^^^^

* The :class:`RequestFactory.trace() <django.test.RequestFactory>`
  and :class:`Client.trace() <django.test.Client.trace>` methods were
  implemented, allowing you to create ``TRACE`` requests in your tests.

* The ``count`` argument was added to
  :meth:`~django.test.SimpleTestCase.assertTemplateUsed`. This allows you to
  assert that a template was rendered a specific number of times.

* The new :meth:`~django.test.SimpleTestCase.assertJSONNotEqual` assertion
  allows you to test that two JSON fragments are not equal.

* Added options to the :djadmin:`test` command to preserve the test database
  (:djadminopt:`--keepdb`), to run the test cases in reverse order
  (:djadminopt:`--reverse`), and to enable SQL logging for failing tests
  (:djadminopt:`--debug-sql`).

* Added the :attr:`~django.test.Response.resolver_match` attribute to test
  client responses.

* Added several settings that allow customization of test tablespace parameters
  for Oracle: :setting:`DATAFILE`, :setting:`DATAFILE_TMP`,
  :setting:`DATAFILE_MAXSIZE` and :setting:`DATAFILE_TMP_MAXSIZE`.

* The :func:`~django.test.override_settings` decorator can now affect the
  master router in :setting:`DATABASE_ROUTERS`.

* Added test client support for file uploads with file-like objects.

* A shared cache is now used when testing with a SQLite in-memory database when
  using Python 3.4+ and SQLite 3.7.13+. This allows sharing the database
  between threads.

Validators
^^^^^^^^^^

* :class:`~django.core.validators.URLValidator` now supports IPv6 addresses,
  unicode domains, and URLs containing authentication data.

Backwards incompatible changes in 1.8
=====================================

.. warning::

    In addition to the changes outlined in this section, be sure to review the
    :ref:`deprecation plan <deprecation-removed-in-1.8>` for any features that
    have been removed. If you haven't updated your code within the
    deprecation timeline for a given feature, its removal may appear as a
    backwards incompatible change.

Related object operations are run in a transaction
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Some operations on related objects such as
:meth:`~django.db.models.fields.related.RelatedManager.add()` or
:ref:`direct assignment<direct-assignment>` ran multiple data modifying
queries without wrapping them in transactions. To reduce the risk of data
corruption, all data modifying methods that affect multiple related objects
(i.e. ``add()``, ``remove()``, ``clear()``, and :ref:`direct assignment
<direct-assignment>`) now perform their data modifying queries from within a
transaction, provided your database supports transactions.

This has one backwards incompatible side effect, signal handlers triggered from
these methods are now executed within the method's transaction and any
exception in a signal handler will prevent the whole operation.

.. _unsaved-model-instance-check-18:

Assigning unsaved objects to relations raises an error
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

.. note::

    To more easily allow in-memory usage of models, this change was reverted in
    Django 1.8.4 and replaced with a check during ``model.save()``. For example::

        >>> book = Book.objects.create(name="Django")
        >>> book.author = Author(name="John")
        >>> book.save()
        Traceback (most recent call last):
        ...
        ValueError: save() prohibited to prevent data loss due to unsaved related object 'author'.

    A similar check on assignment to reverse one-to-one relations was removed
    in Django 1.8.5.

Assigning unsaved objects to a :class:`~django.db.models.ForeignKey`,
:class:`~django.contrib.contenttypes.fields.GenericForeignKey`, and
:class:`~django.db.models.OneToOneField` now raises a :exc:`ValueError`.

Previously, the assignment of an unsaved object would be silently ignored.
For example::

    >>> book = Book.objects.create(name="Django")
    >>> book.author = Author(name="John")
    >>> book.author.save()
    >>> book.save()

    >>> Book.objects.get(name="Django")
    >>> book.author
    >>>

Now, an error will be raised to prevent data loss::

    >>> book.author = Author(name="john")
    Traceback (most recent call last):
    ...
    ValueError: Cannot assign "<Author: John>": "Author" instance isn't saved in the database.

If you require allowing the assignment of unsaved instances (the old behavior)
and aren't concerned about the data loss possibility (e.g. you never save the
objects to the database), you can disable this check by using the
``ForeignKey.allow_unsaved_instance_assignment`` attribute. (This attribute was
removed in 1.8.4 as it's no longer relevant.)

Management commands that only accept positional arguments
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

If you have written a custom management command that only accepts positional
arguments and you didn't specify the ``args`` command variable, you might get
an error like ``Error: unrecognized arguments: ...``, as variable parsing is
now based on :py:mod:`argparse` which doesn't implicitly accept positional
arguments. You can make your command backwards compatible by simply setting the
``args`` class variable. However, if you don't have to keep compatibility with
older Django versions, it's better to implement the new
:meth:`~django.core.management.BaseCommand.add_arguments` method as described
in :doc:`/howto/custom-management-commands`.

Custom test management command arguments through test runner
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The method to add custom arguments to the `test` management command through the
test runner has changed. Previously, you could provide an `option_list` class
variable on the test runner to add more arguments (à la :py:mod:`optparse`).
Now to implement the same behavior, you have to create an
``add_arguments(cls, parser)`` class method on the test runner and call
``parser.add_argument`` to add any custom arguments, as parser is now an
:py:class:`argparse.ArgumentParser` instance.

Model check ensures auto-generated column names are within limits specified by database
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

A field name that's longer than the column name length supported by a database
can create problems. For example, with MySQL you'll get an exception trying to
create the column, and with PostgreSQL the column name is truncated by the
database (you may see a warning in the PostgreSQL logs).

A model check has been introduced to better alert users to this scenario before
the actual creation of database tables.

If you have an existing model where this check seems to be a false positive,
for example on PostgreSQL where the name was already being truncated, simply
use :attr:`~django.db.models.Field.db_column` to specify the name that's being
used.

The check also applies to the columns generated in an implicit
``ManyToManyField.through`` model. If you run into an issue there, use
:attr:`~django.db.models.ManyToManyField.through` to create an explicit model
and then specify :attr:`~django.db.models.Field.db_column` on its column(s)
as needed.

Query relation lookups now check object types
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Querying for model lookups now checks if the object passed is of correct type
and raises a :exc:`ValueError` if not. Previously, Django didn't care if the
object was of correct type; it just used the object's related field attribute
(e.g. ``id``) for the lookup. Now, an error is raised to prevent incorrect
lookups::

    >>> book = Book.objects.create(name="Django")
    >>> book = Book.objects.filter(author=book)
    Traceback (most recent call last):
    ...
    ValueError: Cannot query "<Book: Django>": Must be "Author" instance.

``select_related()`` now checks given fields
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

``select_related()`` now validates that the given fields actually exist.
Previously, nonexistent fields were silently ignored. Now, an error is raised::

    >>> book = Book.objects.select_related('nonexistent_field')
    Traceback (most recent call last):
    ...
    FieldError: Invalid field name(s) given in select_related: 'nonexistent_field'

The validation also makes sure that the given field is relational::

    >>> book = Book.objects.select_related('name')
    Traceback (most recent call last):
    ...
    FieldError: Non-relational field given in select_related: 'name'

Default ``EmailField.max_length`` increased to 254
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The old default 75 character ``max_length`` was not capable of storing all
possible RFC3696/5321-compliant email addresses. In order to store all
possible valid email addresses, the ``max_length`` has been increased to 254
characters. You will need to generate and apply database migrations for your
affected models (or add ``max_length=75`` if you wish to keep the length on
your current fields). A migration for
:attr:`django.contrib.auth.models.User.email` is included.

Support for PostgreSQL versions older than 9.0
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The end of upstream support periods was reached in July 2014 for PostgreSQL 8.4.
As a consequence, Django 1.8 sets 9.0 as the minimum PostgreSQL version it
officially supports.

This also includes dropping support for PostGIS 1.3 and 1.4 as these versions
are not supported on versions of PostgreSQL later than 8.4.

Django also now requires the use of Psycopg2 version 2.4.5 or higher (or 2.5+
if you want to use :mod:`django.contrib.postgres`).

Support for MySQL versions older than 5.5
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The end of upstream support periods was reached in January 2012 for MySQL 5.0
and December 2013 for MySQL 5.1. As a consequence, Django 1.8 sets 5.5 as the
minimum MySQL version it officially supports.

Support for Oracle versions older than 11.1
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The end of upstream support periods was reached in July 2010 for Oracle 9.2,
January 2012 for Oracle 10.1, and July 2013 for Oracle 10.2. As a consequence,
Django 1.8 sets 11.1 as the minimum Oracle version it officially supports.

Specific privileges used instead of roles for tests on Oracle
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Earlier versions of Django granted the CONNECT and RESOURCE roles to the test
user on Oracle. These roles have been deprecated, so Django 1.8 uses the
specific underlying privileges instead. This changes the privileges required
of the main user for running tests (unless the project is configured to avoid
creating a test user). The exact privileges required now are detailed in
:ref:`Oracle notes <oracle-notes>`.

``AbstractUser.last_login`` allows null values
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The :attr:`AbstractUser.last_login <django.contrib.auth.models.User.last_login>`
field now allows null values. Previously, it defaulted to the time when the user
was created which was misleading if the user never logged in. If you are using
the default user (:class:`django.contrib.auth.models.User`), run the database
migration included in ``contrib.auth``.

If you are using a custom user model that inherits from ``AbstractUser``,
you'll need to run :djadmin:`makemigrations` and generate a migration for your
app that contains that model. Also, if wish to set ``last_login`` to ``NULL``
for users who haven't logged in, you can run this query::

    from django.db import models
    from django.contrib.auth import get_user_model
    from django.contrib.auth.models import AbstractBaseUser

    UserModel = get_user_model()
    if issubclass(UserModel, AbstractBaseUser):
        UserModel._default_manager.filter(
            last_login=models.F('date_joined')
        ).update(last_login=None)

:mod:`django.contrib.gis`
~~~~~~~~~~~~~~~~~~~~~~~~~

* Support for GEOS 3.1 and GDAL 1.6 has been dropped.

* Support for SpatiaLite < 2.4 has been dropped.

* GIS-specific lookups have been refactored to use the
  :class:`django.db.models.Lookup` API.

* The default ``str`` representation of
  :class:`~django.contrib.gis.geos.GEOSGeometry` objects has been changed from
  WKT to EWKT format (including the SRID). As this representation is used in
  the serialization framework, that means that ``dumpdata`` output will now
  contain the SRID value of geometry objects.

Priority of context processors for ``TemplateResponse`` brought in line with ``render``
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The :class:`~django.template.response.TemplateResponse` constructor is designed to be a
drop-in replacement for the :func:`~django.shortcuts.render` function. However,
it had a slight incompatibility, in that for ``TemplateResponse``, context data
from the passed in context dictionary could be shadowed by context data returned
from context processors, whereas for ``render`` it was the other way
around. This was a bug, and the behavior of ``render`` is more appropriate,
since it allows the globally defined context processors to be overridden locally
in the view. If you were relying on the fact context data in a
``TemplateResponse`` could be overridden using a context processor, you will
need to change your code.

Overriding ``setUpClass`` / ``tearDownClass`` in test cases
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The decorators :func:`~django.test.override_settings` and
:func:`~django.test.modify_settings` now act at the class level when used as
class decorators. As a consequence, when overriding ``setUpClass()`` or
``tearDownClass()``, the ``super`` implementation should always be called.

Removal of ``django.contrib.formtools``
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The formtools contrib app has been moved to a separate package and the
relevant documentation pages have been updated or removed.

The new package is available `on Github`_ and on PyPI.

.. _on GitHub: https://github.com/django/django-formtools/

Database connection reloading between tests
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Django previously closed database connections between each test within a
``TestCase``. This is no longer the case as Django now wraps the whole
``TestCase`` within a transaction. If some of your tests relied on the old
behavior, you should have them inherit from ``TransactionTestCase`` instead.

Cleanup of the ``django.template`` namespace
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

If you've been relying on private APIs exposed in the ``django.template``
module, you may have to import them from ``django.template.base`` instead.

Also private APIs ``django.template.base.compile_string()``,
``django.template.loader.find_template()``, and
``django.template.loader.get_template_from_string()`` were removed.

``model`` attribute on private model relations
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

In earlier versions of Django, on a model with a reverse foreign key
relationship (for example), ``model._meta.get_all_related_objects()`` returned
the relationship as a ``django.db.models.related.RelatedObject`` with the
``model`` attribute set to the source of the relationship. Now, this method
returns the relationship as ``django.db.models.fields.related.ManyToOneRel``
(private API ``RelatedObject`` has been removed), and the ``model`` attribute
is set to the target of the relationship instead of the source. The source
model is accessible on the ``related_model`` attribute instead.

Consider this example from the tutorial in Django 1.8::

    >>> p = Poll.objects.get(pk=1)
    >>> p._meta.get_all_related_objects()
    [<ManyToOneRel: polls.choice>]
    >>> p._meta.get_all_related_objects()[0].model
    <class 'polls.models.Poll'>
    >>> p._meta.get_all_related_objects()[0].related_model
    <class 'polls.models.Choice'>

and compare it to the behavior on older versions::

    >>> p._meta.get_all_related_objects()
    [<RelatedObject: polls:choice related to poll>]
    >>> p._meta.get_all_related_objects()[0].model
    <class 'polls.models.Choice'>

To access the source model, you can use a pattern like this to write code that
will work with both Django 1.8 and older versions::

    for relation in opts.get_all_related_objects():
        to_model = getattr(relation, 'related_model', relation.model)

Also note that ``get_all_related_objects()`` is deprecated in 1.8. See the
:ref:`upgrade guide <migrating-old-meta-api>` for the new API.

Database backend API
~~~~~~~~~~~~~~~~~~~~

The following changes to the database backend API are documented to assist
those writing third-party backends in updating their code:

* ``BaseDatabaseXXX`` classes have been moved to ``django.db.backends.base``.
  Please import them from the new locations::

    from django.db.backends.base.base import BaseDatabaseWrapper
    from django.db.backends.base.client import BaseDatabaseClient
    from django.db.backends.base.creation import BaseDatabaseCreation
    from django.db.backends.base.features import BaseDatabaseFeatures
    from django.db.backends.base.introspection import BaseDatabaseIntrospection
    from django.db.backends.base.introspection import FieldInfo, TableInfo
    from django.db.backends.base.operations import BaseDatabaseOperations
    from django.db.backends.base.schema import BaseDatabaseSchemaEditor
    from django.db.backends.base.validation import BaseDatabaseValidation

* The ``data_types``, ``data_types_suffix``, and
  ``data_type_check_constraints`` attributes have moved from the
  ``DatabaseCreation`` class to ``DatabaseWrapper``.

* The ``SQLCompiler.as_sql()`` method now takes a ``subquery`` parameter
  (:ticket:`24164`).

* The ``BaseDatabaseOperations.date_interval_sql()`` method now only takes a
  ``timedelta`` parameter.

:mod:`django.contrib.admin`
~~~~~~~~~~~~~~~~~~~~~~~~~~~

* ``AdminSite`` no longer takes an ``app_name`` argument and its ``app_name``
  attribute has been removed. The application name is always ``admin`` (as
  opposed to the instance name which you can still customize using
  ``AdminSite(name="...")``.

* The ``ModelAdmin.get_object()`` method (private API) now takes a third
  argument named ``from_field`` in order to specify which field should match
  the provided ``object_id``.

* The :meth:`ModelAdmin.response_delete()
  <django.contrib.admin.ModelAdmin.response_delete>` method
  now takes a second argument named ``obj_id`` which is the serialized
  identifier used to retrieve the object before deletion.

Default autoescaping of functions in ``django.template.defaultfilters``
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

In order to make built-in template filters that output HTML "safe by default"
when calling them in Python code, the following functions in
``django.template.defaultfilters`` have been changed to automatically escape
their input value:

* ``join``
* ``linebreaksbr``
* ``linebreaks_filter``
* ``linenumbers``
* ``unordered_list``
* ``urlize``
* ``urlizetrunc``

You can revert to the old behavior by specifying ``autoescape=False`` if you
are passing trusted content. This change doesn't have any effect when using
the corresponding filters in templates.

Miscellaneous
~~~~~~~~~~~~~

* ``connections.queries`` is now a read-only attribute.

* Database connections are considered equal only if they're the same object.
  They aren't hashable any more.

* :class:`~django.middleware.gzip.GZipMiddleware` used to disable compression
  for some content types when the request is from Internet Explorer, in order
  to work around a bug in IE6 and earlier. This behavior could affect
  performance on IE7 and later. It was removed.

* ``URLField.to_python`` no longer adds a trailing slash to pathless URLs.

* The :tfilter:`length` template filter now returns ``0`` for an undefined
  variable, rather than an empty string.

* ``ForeignKey.default_error_message['invalid']`` has been changed from
  ``'%(model)s instance with pk %(pk)r does not exist.'`` to
  ``'%(model)s instance with %(field)s %(value)r does not exist.'`` If you are
  using this message in your own code, please update the list of interpolated
  parameters. Internally, Django will continue to provide the
  ``pk`` parameter in ``params`` for backwards compatibility.

* ``UserCreationForm.errors_messages['duplicate_username']`` is no longer used.
  If you wish to customize that error message, :ref:`override it on the form
  <modelforms-overriding-default-fields>` using the ``'unique'`` key in
  ``Meta.errors_messages['username']`` or, if you have a custom form field for
  ``'username'``, using the the ``'unique'`` key in its
  :attr:`~django.forms.Field.error_messages` argument.

* The block ``usertools`` in the ``base.html`` template of
  :mod:`django.contrib.admin` now requires the ``has_permission`` context
  variable to be set. If you have any custom admin views that use this
  template, update them to pass :meth:`AdminSite.has_permission()
  <django.contrib.admin.AdminSite.has_permission>` as this new variable's
  value or simply include :meth:`AdminSite.each_context(request)
  <django.contrib.admin.AdminSite.each_context>` in the context.

* Internal changes were made to the :class:`~django.forms.ClearableFileInput`
  widget to allow more customization. The undocumented ``url_markup_template``
  attribute was removed in favor of ``template_with_initial``.

* For consistency with other major vendors, the ``en_GB`` locale now has Monday
  as the first day of the week.

* Seconds have been removed from any locales that had them in ``TIME_FORMAT``,
  ``DATETIME_FORMAT``, or ``SHORT_DATETIME_FORMAT``.

* The default max size of the Oracle test tablespace has increased from 300M
  (or 200M, before 1.7.2) to 500M.

* :func:`~django.core.urlresolvers.reverse` and
  :func:`~django.core.urlresolvers.reverse_lazy` now return Unicode strings
  instead of byte strings.

* The ``CacheClass`` shim has been removed from all cache backends.
  These aliases were provided for backwards compatibility with Django 1.3.
  If you are still using them, please update your project to use the real
  class name found in the :setting:`BACKEND <CACHES-BACKEND>` key of the
  :setting:`CACHES` setting.

* By default, :ref:`call_command <call-command>` now always skips the check
  framework (unless you pass it ``skip_checks=False``).

* When iterating over lines, :class:`~django.core.files.File` now uses
  `universal newlines`_. The following are recognized as ending a line: the
  Unix end-of-line convention ``'\n'``, the Windows convention ``'\r\n'``, and
  the old Macintosh convention ``'\r'``.

  .. _universal newlines: https://www.python.org/dev/peps/pep-0278

* The Memcached cache backends ``MemcachedCache`` and ``PyLibMCCache`` will
  delete a key if ``set()`` fails. This is necessary to ensure the ``cache_db``
  session store always fetches the most current session data.

* Private APIs ``override_template_loaders`` and ``override_with_test_loader``
  in ``django.test.utils`` were removed. Override ``TEMPLATES`` with
  ``override_settings`` instead.

* Warnings from the MySQL database backend are no longer converted to
  exceptions when :setting:`DEBUG` is ``True``.

* :class:`~django.http.HttpRequest` now has a simplified ``repr`` (e.g.
  ``<WSGIRequest: GET '/somepath/'>``). This won't change the behavior of
  the :class:`~django.views.debug.SafeExceptionReporterFilter` class.

* Class-based views that use :class:`~django.views.generic.edit.ModelFormMixin`
  will raise an :exc:`~django.core.exceptions.ImproperlyConfigured` exception
  when both the ``fields`` and ``form_class`` attributes are specified.
  Previously, ``fields`` was silently ignored.

* When following redirects, the test client now raises
  :exc:`~django.test.client.RedirectCycleError` if it detects a loop or hits a
  maximum redirect limit (rather than passing silently).

* Translatable strings set as the ``default`` parameter of the field are cast
  to concrete strings later, so the return type of ``Field.get_default()`` is
  different in some cases. There is no change to default values which are the
  result of a callable.

* ``GenericIPAddressField.empty_strings_allowed`` is now ``False``. Database
  backends that interpret empty strings as null (only Oracle among the backends
  that Django includes) will no longer convert null values back to an empty
  string. This is consistent with other backends.

* When the :attr:`~django.core.management.BaseCommand.leave_locale_alone`
  attribute is ``False``, translations are now deactivated instead of forcing
  the "en-us" locale. In the case your models contained non-English strings and
  you counted on English translations to be activated in management commands,
  this will not happen any longer. It might be that new database migrations are
  generated (once) after migrating to 1.8.

* :func:`django.utils.translation.get_language()` now returns ``None`` instead
  of :setting:`LANGUAGE_CODE` when translations are temporarily deactivated.

* When a translation doesn't exist for a specific literal, the fallback is now
  taken from the :setting:`LANGUAGE_CODE` language (instead of from the
  untranslated ``msgid`` message).

* The ``name`` field of :class:`django.contrib.contenttypes.models.ContentType`
  has been removed by a migration and replaced by a property. That means it's
  not possible to query or filter a ``ContentType`` by this field any longer.

* :djadmin:`migrate` now accepts the :djadminopt:`--fake-initial` option to
  allow faking initial migrations. In 1.7 initial migrations were always
  automatically faked if all tables created in an initial migration already
  existed.

* An app *without* migrations with a ``ForeignKey`` to an app *with* migrations
  may now result in a foreign key constraint error when migrating the database
  or running tests. In Django 1.7, this could fail silently and result in a
  missing constraint. To resolve the error, add migrations to the app without
  them.

.. _deprecated-features-1.8:

Features deprecated in 1.8
==========================

Selected methods in ``django.db.models.options.Options``
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

As part of the formalization of the ``Model._meta`` API (from the
:class:`django.db.models.options.Options` class), a number of methods have been
deprecated and will be removed in Django 1.10:

* ``get_all_field_names()``
* ``get_all_related_objects()``
* ``get_all_related_objects_with_model()``
* ``get_all_related_many_to_many_objects()``
* ``get_all_related_m2m_objects_with_model()``
* ``get_concrete_fields_with_model()``
* ``get_field_by_name()``
* ``get_fields_with_model()``
* ``get_m2m_with_model()``

A :ref:`migration guide <migrating-old-meta-api>` has been provided to assist
in converting your code from the old API to the new, official API.

Loading ``cycle`` and ``firstof`` template tags from ``future`` library
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Django 1.6 introduced ``{% load cycle from future %}`` and
``{% load firstof from future %}`` syntax for forward compatibility of the
:ttag:`cycle` and :ttag:`firstof` template tags. This syntax is now deprecated
and will be removed in Django 1.10. You can simply remove the
``{% load ... from future %}`` tags.

``django.conf.urls.patterns()``
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

In the olden days of Django, it was encouraged to reference views as strings
in ``urlpatterns``::

    urlpatterns = patterns('',
        url('^$', 'myapp.views.myview'),
    )

and Django would magically import ``myapp.views.myview`` internally and turn
the string into a real function reference. In order to reduce repetition when
referencing many views from the same module, the ``patterns()`` function takes
a required initial ``prefix`` argument which is prepended to all
views-as-strings in that set of ``urlpatterns``::

    urlpatterns = patterns('myapp.views',
        url('^$', 'myview'),
        url('^other/$', 'otherview'),
    )

In the modern era, we have updated the tutorial to instead recommend importing
your views module and referencing your view functions (or classes) directly.
This has a number of advantages, all deriving from the fact that we are using
normal Python in place of "Django String Magic": the errors when you mistype a
view name are less obscure, IDEs can help with autocompletion of view names,
etc.

So these days, the above use of the ``prefix`` arg is much more likely to be
written (and is better written) as::

    from myapp import views

    urlpatterns = patterns('',
        url('^$', views.myview),
        url('^other/$', views.otherview),
    )

Thus ``patterns()`` serves little purpose and is a burden when teaching new users
(answering the newbie's question "why do I need this empty string as the first
argument to ``patterns()``?"). For these reasons, we are deprecating it.
Updating your code is as simple as ensuring that ``urlpatterns`` is a list of
:func:`django.conf.urls.url` instances. For example::

    from django.conf.urls import url
    from myapp import views

    urlpatterns = [
        url('^$', views.myview),
        url('^other/$', views.otherview),
    ]

Passing a string as ``view`` to :func:`~django.conf.urls.url`
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Related to the previous item, referencing views as strings in the ``url()``
function is deprecated. Pass the callable view as described in the previous
section instead.

Template-related settings
~~~~~~~~~~~~~~~~~~~~~~~~~

As a consequence of the multiple template engines refactor, several settings
are deprecated in favor of :setting:`TEMPLATES`:

* ``ALLOWED_INCLUDE_ROOTS``
* ``TEMPLATE_CONTEXT_PROCESSORS``
* ``TEMPLATE_DEBUG``
* ``TEMPLATE_DIRS``
* ``TEMPLATE_LOADERS``
* ``TEMPLATE_STRING_IF_INVALID``

``django.core.context_processors``
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Built-in template context processors have been moved to
``django.template.context_processors``.

``django.test.SimpleTestCase.urls``
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The attribute ``SimpleTestCase.urls`` for specifying URLconf configuration in
tests has been deprecated and will be removed in Django 1.10. Use
:func:`@override_settings(ROOT_URLCONF=...) <django.test.override_settings>`
instead.

``prefix`` argument to :func:`~django.conf.urls.i18n.i18n_patterns`
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Related to the previous item, the ``prefix`` argument to
:func:`django.conf.urls.i18n.i18n_patterns` has been deprecated. Simply pass a
list of :func:`django.conf.urls.url` instances instead.

Using an incorrect count of unpacked values in the :ttag:`for` template tag
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Using an incorrect count of unpacked values in :ttag:`for` tag will raise an
exception rather than fail silently in Django 1.10.

Passing a dotted path to :func:`~django.core.urlresolvers.reverse()` and :ttag:`url`
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Reversing URLs by Python path is an expensive operation as it causes the
path being reversed to be imported. This behavior has also resulted in a
`security issue`_. Use :ref:`named URL patterns <naming-url-patterns>`
for reversing instead.

If you are using :mod:`django.contrib.sitemaps`, add the ``name`` argument to
the ``url`` that references :func:`django.contrib.sitemaps.views.sitemap`::

    from django.contrib.sitemaps.views import sitemap

    url(r'^sitemap\.xml$', sitemap, {'sitemaps': sitemaps},
        name='django.contrib.sitemaps.views.sitemap')

to ensure compatibility when reversing by Python path is removed in Django 1.10.

Similarly for GIS sitemaps, add ``name='django.contrib.gis.sitemaps.views.kml'``
or ``name='django.contrib.gis.sitemaps.views.kmz'``.

.. _security issue: https://www.djangoproject.com/weblog/2014/apr/21/security/#s-issue-unexpected-code-execution-using-reverse

Aggregate methods and modules
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The ``django.db.models.sql.aggregates`` and
``django.contrib.gis.db.models.sql.aggregates`` modules (both private API), have
been deprecated as ``django.db.models.aggregates`` and
``django.contrib.gis.db.models.aggregates`` are now also responsible
for SQL generation. The old modules will be removed in Django 1.10.

If you were using the old modules, see :doc:`Query Expressions
</ref/models/expressions>` for instructions on rewriting custom aggregates
using the new stable API.

The following methods and properties of ``django.db.models.sql.query.Query``
have also been deprecated and the backwards compatibility shims will be removed
in Django 1.10:

* ``Query.aggregates``, replaced by ``annotations``.
* ``Query.aggregate_select``, replaced by ``annotation_select``.
* ``Query.add_aggregate()``, replaced by ``add_annotation()``.
* ``Query.set_aggregate_mask()``, replaced by ``set_annotation_mask()``.
* ``Query.append_aggregate_mask()``, replaced by ``append_annotation_mask()``.

Extending management command arguments through ``Command.option_list``
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Management commands now use :py:mod:`argparse` instead of :py:mod:`optparse` to
parse command-line arguments passed to commands. This also means that the way
to add custom arguments to commands has changed: instead of extending the
``option_list`` class list, you should now override the
:meth:`~django.core.management.BaseCommand.add_arguments` method and add
arguments through ``argparse.add_argument()``. See
:ref:`this example <custom-commands-options>` for more details.

``django.core.management.NoArgsCommand``
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The class ``NoArgsCommand`` is now deprecated and will be removed in Django
1.10. Use :class:`~django.core.management.BaseCommand` instead, which takes no
arguments by default.

Listing all migrations in a project
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The ``--list`` option of the :djadmin:`migrate` management command is
deprecated and will be removed in Django 1.10. Use :djadmin:`showmigrations`
instead.

``cache_choices`` option of ``ModelChoiceField`` and ``ModelMultipleChoiceField``
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

:class:`~django.forms.ModelChoiceField` and
:class:`~django.forms.ModelMultipleChoiceField` took an undocumented, untested
option ``cache_choices``. This cached querysets between multiple renderings of
the same ``Form`` object. This option is subject to an accelerated deprecation
and will be removed in Django 1.9.

``django.template.resolve_variable()``
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The function has been informally marked as "Deprecated" for some time. Replace
``resolve_variable(path, context)`` with
``django.template.Variable(path).resolve(context)``.

``django.contrib.webdesign``
~~~~~~~~~~~~~~~~~~~~~~~~~~~~

It provided the :ttag:`lorem` template tag which is now included in the
built-in tags. Simply remove ``'django.contrib.webdesign'`` from
:setting:`INSTALLED_APPS` and ``{% load webdesign %}`` from your templates.

``error_message`` argument to ``django.forms.RegexField``
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

It provided backwards compatibility for pre-1.0 code, but its functionality is
redundant. Use ``Field.error_messages['invalid']`` instead.

Old :tfilter:`unordered_list` syntax
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

An older (pre-1.0), more restrictive and verbose input format for the
:tfilter:`unordered_list` template filter has been deprecated::

    ``['States', [['Kansas', [['Lawrence', []], ['Topeka', []]]], ['Illinois', []]]]``

Using the new syntax, this becomes::

    ``['States', ['Kansas', ['Lawrence', 'Topeka'], 'Illinois']]``

``django.forms.Field._has_changed()``
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Rename this method to :meth:`~django.forms.Field.has_changed` by removing the
leading underscore. The old name will still work until Django 1.10.

``django.utils.html.remove_tags()`` and ``removetags`` template filter
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

``django.utils.html.remove_tags()`` as well as the template filter
``removetags`` have been deprecated as they cannot guarantee safe output. Their
existence is likely to lead to their use in security-sensitive contexts where
they are not actually safe.

The unused and undocumented ``django.utils.html.strip_entities()`` function has
also been deprecated.

``is_admin_site`` argument to ``django.contrib.auth.views.password_reset()``
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

It's a legacy option that should no longer be necessary.

``SubfieldBase``
~~~~~~~~~~~~~~~~

``django.db.models.fields.subclassing.SubfieldBase`` has been deprecated and
will be removed in Django 1.10. Historically, it was used to handle fields where
type conversion was needed when loading from the database, but it was not used
in ``.values()`` calls or in aggregates. It has been replaced with
:meth:`~django.db.models.Field.from_db_value`. Note that the new approach does
not call the :meth:`~django.db.models.Field.to_python` method on assignment
as was the case with ``SubfieldBase``.

``django.utils.checksums``
~~~~~~~~~~~~~~~~~~~~~~~~~~

The ``django.utils.checksums`` module has been deprecated and will be removed
in Django 1.10. The functionality it provided (validating checksum using the
Luhn algorithm) was undocumented and not used in Django. The module has been
moved to the `django-localflavor`_ package (version 1.1+).

.. _django-localflavor: https://pypi.python.org/pypi/django-localflavor

``InlineAdminForm.original_content_type_id``
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The ``original_content_type_id`` attribute on ``InlineAdminForm`` has been
deprecated and will be removed in Django 1.10. Historically, it was used
to construct the "view on site" URL. This URL is now accessible using the
``absolute_url`` attribute of the form.

``django.views.generic.edit.FormMixin.get_form()``’s ``form_class`` argument
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

``FormMixin`` subclasses that override the ``get_form()`` method should make
sure to provide a default value for the ``form_class`` argument since it's
now optional.

Rendering templates loaded by :func:`~django.template.loader.get_template()` with a :class:`~django.template.Context`
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The return type of :func:`~django.template.loader.get_template()` has changed
in Django 1.8: instead of a :class:`django.template.Template`, it returns a
``Template`` instance whose exact type depends on which backend loaded it.

Both classes provide a ``render()`` method, however, the former takes a
:class:`django.template.Context` as an argument while the latter expects a
:class:`dict`. This change is enforced through a deprecation path for Django
templates.

Since it's easier to understand with examples, the :ref:`upgrade guide
<get_template-upgrade-django-18>` shows how to adapt affected code.

All this also applies to :func:`~django.template.loader.select_template()`.

:class:`~django.template.Template` and :class:`~django.template.Context` classes in template responses
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Some methods of :class:`~django.template.response.SimpleTemplateResponse` and
:class:`~django.template.response.TemplateResponse` accepted
:class:`django.template.Context` and :class:`django.template.Template` objects
as arguments. They should now receive :class:`dict` and backend-dependent
template objects respectively.

This also applies to the return types if you have subclassed either template
response class.

Check the :doc:`template response API documentation </ref/template-response>`
for details.

``current_app`` argument of template-related APIs
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The following functions and classes will no longer accept a ``current_app``
parameter to set an URL namespace in Django 1.10:

* ``django.shortcuts.render()``
* ``django.template.Context()``
* ``django.template.RequestContext()``
* ``django.template.response.TemplateResponse()``

Set ``request.current_app`` instead, where ``request`` is the first argument
to these functions or classes. If you're using a plain ``Context``, use a
``RequestContext`` instead.

``dictionary`` and ``context_instance`` arguments of rendering functions
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The following functions will no longer accept the ``dictionary`` and
``context_instance`` parameters in Django 1.10:

* ``django.shortcuts.render()``
* ``django.shortcuts.render_to_response()``
* ``django.template.loader.render_to_string()``

Use the ``context`` parameter instead. When ``dictionary`` is passed as a
positional argument, which is the most common idiom, no changes are needed.

If you're passing a :class:`~django.template.Context` in ``context_instance``,
pass a :class:`dict` in the ``context`` parameter instead. If you're passing a
:class:`~django.template.RequestContext`, pass the request separately in the
``request`` parameter.

``dirs`` argument of template-finding functions
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The following functions will no longer accept a ``dirs`` parameter to override
``TEMPLATE_DIRS`` in Django 1.10:

* :func:`django.template.loader.get_template()`
* :func:`django.template.loader.select_template()`
* :func:`django.shortcuts.render()`
* :func:`django.shortcuts.render_to_response()`

The parameter didn't work consistently across different template loaders and
didn't work for included templates.

``django.template.loader.BaseLoader``
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

``django.template.loader.BaseLoader`` was renamed to
``django.template.loaders.base.Loader``. If you've written a custom template
loader that inherits ``BaseLoader``, you must inherit ``Loader`` instead.

``django.test.utils.TestTemplateLoader``
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Private API ``django.test.utils.TestTemplateLoader`` is deprecated in favor of
``django.template.loaders.locmem.Loader`` and will be removed in Django 1.9.

.. _storage-max-length-update:

Support for the ``max_length`` argument on custom ``Storage`` classes
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

``Storage`` subclasses should add ``max_length=None`` as a parameter to
:meth:`~django.core.files.storage.Storage.get_available_name` and/or
:meth:`~django.core.files.storage.Storage.save` if they override either method.
Support for storages that do not accept this argument will be removed in
Django 1.10.

``qn`` replaced by ``compiler``
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

In previous Django versions, various internal ORM methods (mostly ``as_sql``
methods) accepted a ``qn`` (for "quote name") argument, which was a reference
to a function that quoted identifiers for sending to the database. In Django
1.8, that argument has been renamed to ``compiler`` and is now a full
``SQLCompiler`` instance. For backwards-compatibility, calling a
``SQLCompiler`` instance performs the same name-quoting that the ``qn``
function used to. However, this backwards-compatibility shim is immediately
deprecated: you should rename your ``qn`` arguments to ``compiler``, and call
``compiler.quote_name_unless_alias(...)`` where you previously called
``qn(...)``.

Default value of ``RedirectView.permanent``
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The default value of the
:attr:`RedirectView.permanent <django.views.generic.base.RedirectView.permanent>`
attribute will change from ``True`` to ``False`` in Django 1.9.

Using ``AuthenticationMiddleware`` without ``SessionAuthenticationMiddleware``
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

``django.contrib.auth.middleware.SessionAuthenticationMiddleware`` was
added in Django 1.7. In Django 1.7.2, its functionality was moved to
``auth.get_user()`` and, for backwards compatibility, enabled only if
``'django.contrib.auth.middleware.SessionAuthenticationMiddleware'`` appears in
:setting:`MIDDLEWARE_CLASSES`.

In Django 1.10, session verification will be enabled regardless of whether or not
``SessionAuthenticationMiddleware`` is enabled (at which point
``SessionAuthenticationMiddleware`` will have no significance). You can add it
to your ``MIDDLEWARE_CLASSES`` sometime before then to opt-in. Please read the
:ref:`upgrade considerations <session-invalidation-on-password-change>` first.

``django.contrib.sitemaps.FlatPageSitemap``
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

``django.contrib.sitemaps.FlatPageSitemap`` has moved to
``django.contrib.flatpages.sitemaps.FlatPageSitemap``. The old import location
is deprecated and will be removed in Django 1.9.

Model ``Field.related``
~~~~~~~~~~~~~~~~~~~~~~~

Private attribute ``django.db.models.Field.related`` is deprecated in favor
of ``Field.rel``.  The latter is an instance of
``django.db.models.fields.related.ForeignObjectRel`` which replaces
``django.db.models.related.RelatedObject``. The ``django.db.models.related``
module has been removed and the ``Field.related`` attribute will be removed in
Django 1.10.

``ssi`` template tag
~~~~~~~~~~~~~~~~~~~~

The ``ssi`` template tag allows files to be included in a template by
absolute path. This is of limited use in most deployment situations, and
the :ttag:`include` tag often makes more sense. This tag is now deprecated and
will be removed in Django 1.10.

``=`` as comparison operator in ``if`` template tag
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Using a single equals sign with the ``{% if %}`` template tag for equality
testing was undocumented and untested. It's now deprecated in favor of ``==``.

``%(<foo>)s`` syntax in ``ModelFormMixin.success_url``
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The legacy ``%(<foo>)s`` syntax in :attr:`ModelFormMixin.success_url
<django.views.generic.edit.ModelFormMixin.success_url>` is deprecated and
will be removed in Django 1.10.

``GeoQuerySet`` aggregate methods
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The ``collect()``, ``extent()``, ``extent3d()``, ``make_line()``, and
``unionagg()`` aggregate methods are deprecated and should be replaced by their
function-based aggregate equivalents (``Collect``, ``Extent``, ``Extent3D``,
``MakeLine``, and ``Union``).

.. _deprecated-signature-of-allow-migrate:

Signature of the ``allow_migrate`` router method
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The signature of the :meth:`allow_migrate` method of database routers has
changed from ``allow_migrate(db, model)`` to
``allow_migrate(db, app_label, model_name=None, **hints)``.

When ``model_name`` is set, the value that was previously given through the
``model`` positional argument may now be found inside the ``hints`` dictionary
under the key ``'model'``.

After switching to the new signature the router will also be called by the
:class:`~django.db.migrations.operations.RunPython` and
:class:`~django.db.migrations.operations.RunSQL` operations.

.. removed-features-1.8:

Features removed in 1.8
=======================

These features have reached the end of their deprecation cycle and so have been
removed in Django 1.8 (please see the :ref:`deprecation timeline
<deprecation-removed-in-1.8>` for more details):

* ``django.contrib.comments`` is removed.

* The following transaction management APIs are removed:

  - ``TransactionMiddleware``
  - the decorators and context managers ``autocommit``, ``commit_on_success``,
    and ``commit_manually``, defined in ``django.db.transaction``
  - the functions ``commit_unless_managed`` and ``rollback_unless_managed``,
    also defined in ``django.db.transaction``
  - the ``TRANSACTIONS_MANAGED`` setting

* The :ttag:`cycle` and :ttag:`firstof` template tags auto-escape their
  arguments.

* The ``SEND_BROKEN_LINK_EMAILS`` setting is removed.

* ``django.middleware.doc.XViewMiddleware`` is removed.

* The ``Model._meta.module_name`` alias is removed.

* The backward compatible shims introduced to rename ``get_query_set``
  and similar queryset methods are removed. This affects the following classes:
  ``BaseModelAdmin``, ``ChangeList``, ``BaseCommentNode``,
  ``GenericForeignKey``, ``Manager``, ``SingleRelatedObjectDescriptor`` and
  ``ReverseSingleRelatedObjectDescriptor``.

* The backward compatible shims introduced to rename the attributes
  ``ChangeList.root_query_set`` and ``ChangeList.query_set`` are removed.

* ``django.views.defaults.shortcut`` and ``django.conf.urls.shortcut`` are
  removed.

* Support for the Python Imaging Library (PIL) module is removed.

* The following private APIs are removed:

  - ``django.db.backend``
  - ``django.db.close_connection()``
  - ``django.db.backends.creation.BaseDatabaseCreation.set_autocommit()``
  - ``django.db.transaction.is_managed()``
  - ``django.db.transaction.managed()``

* ``django.forms.widgets.RadioInput`` is removed.

* The module ``django.test.simple`` and the class
  ``django.test.simple.DjangoTestSuiteRunner`` are removed.

* The module ``django.test._doctest`` is removed.

* The ``CACHE_MIDDLEWARE_ANONYMOUS_ONLY`` setting is removed. This change
  affects both ``django.middleware.cache.CacheMiddleware`` and
  ``django.middleware.cache.UpdateCacheMiddleware`` despite the lack of a
  deprecation warning in the latter class.

* Usage of the hard-coded *Hold down "Control", or "Command" on a Mac, to select
  more than one.* string to override or append to user-provided ``help_text`` in
  forms for ``ManyToMany`` model fields is not performed by Django anymore
  either at the model or forms layer.

* The ``Model._meta.get_(add|change|delete)_permission`` methods are removed.

* The session key ``django_language`` is no longer read for backwards
  compatibility.

* Geographic Sitemaps are removed
  (``django.contrib.gis.sitemaps.views.index`` and
  ``django.contrib.gis.sitemaps.views.sitemap``).

* ``django.utils.html.fix_ampersands``, the ``fix_ampersands`` template filter,
  and ``django.utils.html.clean_html`` are removed.
