django1/docs/releases/1.9.txt

============================================
Django 1.9 release notes - UNDER DEVELOPMENT
============================================

Welcome to Django 1.9!

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
1.8 or older versions. We've :ref:`dropped some features
<deprecation-removed-in-1.9>` that have reached the end of their deprecation
cycle, and we've `begun the deprecation process for some features`_.

.. _`new features`: `What's new in Django 1.9`_
.. _`backwards incompatible changes`: `Backwards incompatible changes in 1.9`_
.. _`dropped some features`: `Features removed in 1.9`_
.. _`begun the deprecation process for some features`: `Features deprecated in 1.9`_

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

Like Django 1.8, Django 1.9 requires Python 2.7 or above, though we
**highly recommend** the latest minor release. We've dropped support for
Python 3.2 and 3.3, and added support for Python 3.5.

What's new in Django 1.9
========================

Performing actions after a transaction commit
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The new :func:`~django.db.transaction.on_commit` hook allows performing actions
after a database transaction is successfully committed. This is useful for
tasks such as sending notification emails, creating queued tasks, or
invalidating caches.

This functionality from the `django-transaction-hooks`_ package has been
integrated into Django.

.. _django-transaction-hooks: https://pypi.python.org/pypi/django-transaction-hooks

Password validation
~~~~~~~~~~~~~~~~~~~

Django now offers password validation to help prevent the usage of weak
passwords by users. The validation is integrated in the included password
change and reset forms and is simple to integrate in any other code.
Validation is performed by one or more validators, configured in the new
:setting:`AUTH_PASSWORD_VALIDATORS` setting.

Four validators are included in Django, which can enforce a minimum length,
compare the password to the user's attributes like their name, ensure
passwords aren't entirely numeric, or check against an included list of common
passwords. You can combine multiple validators, and some validators have
custom configuration options. For example, you can choose to provide a custom
list of common passwords. Each validator provides a help text to explain its
requirements to the user.

By default, no validation is performed and all passwords are accepted, so if
you don't set :setting:`AUTH_PASSWORD_VALIDATORS`, you will not see any
change. In new projects created with the default :djadmin:`startproject`
template, a simple set of validators is enabled. To enable basic validation in
the included auth forms for your project, you could set, for example::

    AUTH_PASSWORD_VALIDATORS = [
        {
            'NAME': 'django.contrib.auth.password_validation.UserAttributeSimilarityValidator',
        },
        {
            'NAME': 'django.contrib.auth.password_validation.MinimumLengthValidator',
        },
        {
            'NAME': 'django.contrib.auth.password_validation.CommonPasswordValidator',
        },
        {
            'NAME': 'django.contrib.auth.password_validation.NumericPasswordValidator',
        },
    ]

See :ref:`password-validation` for more details.

Permission mixins for class-based views
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Django now ships with the mixins
:class:`~django.contrib.auth.mixins.AccessMixin`,
:class:`~django.contrib.auth.mixins.LoginRequiredMixin`,
:class:`~django.contrib.auth.mixins.PermissionRequiredMixin`, and
:class:`~django.contrib.auth.mixins.UserPassesTestMixin` to provide the
functionality of the ``django.contrib.auth.decorators`` for class-based views.
These mixins have been taken from, or are at least inspired by, the
`django-braces`_ project.

There are a few differences between Django's and django-braces' implementation,
though:

* The :attr:`~django.contrib.auth.mixins.AccessMixin.raise_exception` attribute
  can only be ``True`` or ``False``. Custom exceptions or callables are not
  supported.

* The :meth:`~django.contrib.auth.mixins.AccessMixin.handle_no_permission`
  method does not take a ``request`` argument. The current request is available
  in ``self.request``.

* The custom ``test_func()`` of :class:`~django.contrib.auth.mixins.UserPassesTestMixin`
  does not take a ``user`` argument. The current user is available in
  ``self.request.user``.

* The :attr:`permission_required <django.contrib.auth.mixins.PermissionRequiredMixin>`
  attribute supports a string (defining one permission) or a list/tuple of
  strings (defining multiple permissions) that need to be fulfilled to grant
  access.

* The new :attr:`~django.contrib.auth.mixins.AccessMixin.permission_denied_message`
  attribute allows passing a message to the ``PermissionDenied`` exception.

.. _django-braces: http://django-braces.readthedocs.org/en/latest/index.html

New styling for ``contrib.admin``
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The admin sports a modern, flat design. It still provides a fully-functional
experience to `YUI's A-grade`_ browsers. Older browser may experience varying
levels of graceful degradation.

.. _YUI's A-grade: https://github.com/yui/yui3/wiki/Graded-Browser-Support

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

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

* Admin views now have ``model_admin`` or ``admin_site`` attributes.

* The URL of the admin change view has been changed (was at
  ``/admin/<app>/<model>/<pk>/`` by default and is now at
  ``/admin/<app>/<model>/<pk>/change/``). This should not affect your
  application unless you have hardcoded admin URLs. In that case, replace those
  links by :ref:`reversing admin URLs <admin-reverse-urls>` instead. Note that
  the old URL still redirects to the new one for backwards compatibility, but
  it may be removed in a future version.

* :meth:`ModelAdmin.get_list_select_related()
  <django.contrib.admin.ModelAdmin.get_list_select_related>` was added to allow
  changing the ``select_related()`` values used in the admin's changelist query
  based on the request.

* The ``available_apps`` context variable, which lists the available
  applications for the current user, has been added to the
  :meth:`AdminSite.each_context() <django.contrib.admin.AdminSite.each_context>`
  method.

* :attr:`AdminSite.empty_value_display
  <django.contrib.admin.AdminSite.empty_value_display>` and
  :attr:`ModelAdmin.empty_value_display
  <django.contrib.admin.ModelAdmin.empty_value_display>` were added to override
  the display of empty values in admin change list. You can also customize the
  value for each field.

* The time picker widget includes a '6 p.m' option for consistency of having
  predefined options every 6 hours.

* JavaScript slug generation now supports Romanian characters.

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

* The default iteration count for the PBKDF2 password hasher has been increased
  by 20%. This backwards compatible change will not affect users who have
  subclassed ``django.contrib.auth.hashers.PBKDF2PasswordHasher`` to change the
  default value.

* The ``BCryptSHA256PasswordHasher`` will now update passwords if its
  ``rounds`` attribute is changed.

* ``AbstractBaseUser`` and ``BaseUserManager`` were moved to a new
  ``django.contrib.auth.base_user`` module so that they can be imported without
  including ``django.contrib.auth`` in :setting:`INSTALLED_APPS` (this raised
  a deprecation warning in older versions and is no longer supported in
  Django 1.9).

* The permission argument of
  :func:`~django.contrib.auth.decorators.permission_required()` accepts all
  kinds of iterables, not only list and tuples.

* The new :class:`~django.contrib.auth.middleware.PersistentRemoteUserMiddleware`
  makes it possible to use ``REMOTE_USER`` for setups where the header is only
  populated on login pages instead of every request in the session.

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

* All ``GeoQuerySet`` methods have been deprecated and replaced by
  :doc:`equivalent database functions </ref/contrib/gis/functions>`. As soon
  as the legacy methods have been replaced in your code, you should even be
  able to remove the special ``GeoManager`` from your GIS-enabled classes.

* The GDAL interface now supports instantiating file-based and in-memory
  :ref:`GDALRaster objects <raster-data-source-objects>` from raw data.
  Setters for raster properties such as projection or pixel values have
  been added.

* For PostGIS users, the new :class:`~django.contrib.gis.db.models.RasterField`
  allows :ref:`storing GDALRaster objects <creating-and-saving-raster-models>`.
  It supports automatic spatial index creation and reprojection when saving a
  model. It does not yet support spatial querying.

* The new :meth:`GDALRaster.warp() <django.contrib.gis.gdal.GDALRaster.warp>`
  method allows warping a raster by specifying target raster properties such as
  origin, width, height, or pixel size (amongst others).

* The new :meth:`GDALRaster.transform()
  <django.contrib.gis.gdal.GDALRaster.transform>` method allows transforming a
  raster into a different spatial reference system by specifying a target
  ``srid``.

* The new :class:`~django.contrib.gis.geoip2.GeoIP2` class allows using
  MaxMind's GeoLite2 databases which includes support for IPv6 addresses.

:mod:`django.contrib.messages`
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

* ...

:mod:`django.contrib.postgres`
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

* Added support for the :lookup:`rangefield.contained_by` lookup for some built
  in fields which correspond to the range fields.

* Added :class:`~django.contrib.postgres.fields.JSONField`.

* Added :doc:`/ref/contrib/postgres/aggregates`.

* Fixed serialization of
  :class:`~django.contrib.postgres.fields.DateRangeField` and
  :class:`~django.contrib.postgres.fields.DateTimeRangeField`.

* Added the :class:`~django.contrib.postgres.functions.TransactionNow` database
  function.

:mod:`django.contrib.redirects`
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

* ...

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

* ...

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

* ...

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

* :func:`~django.contrib.sites.shortcuts.get_current_site` now handles the case
  where ``request.get_host()`` returns ``domain:port``, e.g.
  ``example.com:80``. If the lookup fails because the host does not match a
  record in the database and the host has a port, the port is stripped and the
  lookup is retried with the domain part only.

:mod:`django.contrib.staticfiles`
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

* ...

:mod:`django.contrib.syndication`
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

* ...

Cache
^^^^^

* ``django.core.cache.backends.base.BaseCache`` now has a ``get_or_set()``
  method.

* :func:`django.views.decorators.cache.never_cache` now sends more persuasive
  headers (added ``no-cache, no-store, must-revalidate`` to ``Cache-Control``)
  to better prevent caching.

Email
^^^^^

* ...

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

* :meth:`Storage.get_valid_name()
  <django.core.files.storage.Storage.get_valid_name>` is now called when
  the :attr:`~django.db.models.FileField.upload_to` is a callable.

* :class:`~django.core.files.File` now has the ``seekable()`` method when using
  Python 3.

File Uploads
^^^^^^^^^^^^

* ...

Forms
^^^^^

* :class:`~django.forms.ModelForm` accepts the new ``Meta`` option
  ``field_classes`` to customize the type of the fields. See
  :ref:`modelforms-overriding-default-fields` for details.

* You can now specify the order in which form fields are rendered with the
  :attr:`~django.forms.Form.field_order` attribute, the ``field_order``
  constructor argument , or the :meth:`~django.forms.Form.order_fields` method.

* A form prefix can be specified inside a form class, not only when
  instantiating a form. See :ref:`form-prefix` for details.

* You can now :ref:`specify keyword arguments <custom-formset-form-kwargs>`
  that you want to pass to the constructor of forms in a formset.

* :class:`~django.forms.SlugField` now accepts an
  :attr:`~django.forms.SlugField.allow_unicode` argument to allow Unicode
  characters in slugs.

* :class:`~django.forms.CharField` now accepts a
  :attr:`~django.forms.CharField.strip` argument to strip input data of leading
  and trailing whitespace.  As this defaults to ``True`` this is different
  behavior from previous releases.

* Form fields now support the :attr:`~django.forms.Field.disabled` argument,
  allowing the field widget to be displayed disabled by browsers.

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

* Class-based views generated using ``as_view()`` now have ``view_class``
  and ``view_initkwargs`` attributes.

* :func:`~django.utils.decorators.method_decorator` can now be used to
  :ref:`decorate classes instead of methods <decorating-class-based-views>`.

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

* The :func:`django.views.i18n.set_language` view now properly redirects to
  :ref:`translated URLs <url-internationalization>`, when available.

* The :func:`django.views.i18n.javascript_catalog` view now works correctly
  if used multiple times with different configurations on the same page.

* The :func:`django.utils.timezone.make_aware` function gained an ``is_dst``
  argument to help resolve ambiguous times during DST transitions.

* You can now use locale variants supported by gettext. These are usually used
  for languages which can be written in different scripts, for example Latin
  and Cyrillic (e.g. ``be@latin``).

* Added the :func:`django.views.i18n.json_catalog` view to help build a custom
  client-side i18n library upon Django translations. It returns a JSON object
  containing a translations catalog, formatting settings, and a plural rule.

* Added the ``name_translated`` attribute to the object returned by the
  :ttag:`get_language_info` template tag. Also added a corresponding template
  filter: :tfilter:`language_name_translated`.

* You can now run :djadmin:`compilemessages` from the root directory of your
  project and it will find all the app message files that were created by
  :djadmin:`makemessages`.

* :ttag:`blocktrans` supports assigning its output to a variable using
  ``asvar``.

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

* The new :djadmin:`sendtestemail` command lets you send a test email to
  easily confirm that email sending through Django is working.

* To increase the readability of the SQL code generated by
  :djadmin:`sqlmigrate`, the SQL code generated for each migration operation is
  preceded by the operation's description.

* The :djadmin:`dumpdata` command output is now deterministically ordered.
  Moreover, when the ``--ouput`` option is specified, it also shows a progress
  bar in the terminal.

* The :djadmin:`createcachetable` command now has a ``--dry-run`` flag to
  print out the SQL rather than execute it.

* The :djadmin:`startapp` command creates an ``apps.py`` file and adds
  ``default_app_config`` in ``__init__.py``.

* When using the PostgreSQL backend, the :djadmin:`dbshell` command can connect
  to the database using the password from your settings file (instead of
  requiring it to be manually entered).

Migrations
^^^^^^^^^^

* Initial migrations are now marked with an :attr:`initial = True
  <django.db.migrations.Migration.initial>` class attribute which allows
  :djadminopt:`migrate --fake-initial <--fake-initial>` to more easily detect
  initial migrations.

* Added support for serialization of ``functools.partial`` objects.

Models
^^^^^^

* :meth:`QuerySet.bulk_create() <django.db.models.query.QuerySet.bulk_create>`
  now works on proxy models.

* Database configuration gained a :setting:`TIME_ZONE <DATABASE-TIME_ZONE>`
  option for interacting with databases that store datetimes in local time and
  don't support time zones when :setting:`USE_TZ` is ``True``.

* Added the :meth:`RelatedManager.set()
  <django.db.models.fields.related.RelatedManager.set()>` method to the related
  managers created by ``ForeignKey``, ``GenericForeignKey``, and
  ``ManyToManyField``.

* The :meth:`~django.db.models.fields.related.RelatedManager.add` method on
  a reverse foreign key now has a ``bulk`` parameter to allow executing one
  query regardless of the number of objects being added rather than one query
  per object.

* Added the ``keep_parents`` parameter to :meth:`Model.delete()
  <django.db.models.Model.delete>` to allow deleting only a child's data in a
  model that uses multi-table inheritance.

* :meth:`Model.delete() <django.db.models.Model.delete>`
  and :meth:`QuerySet.delete() <django.db.models.query.QuerySet.delete>` return
  the number of objects deleted.

* Added a system check to prevent defining both ``Meta.ordering`` and
  ``order_with_respect_to`` on the same model.

* :lookup:`Date and time <year>` lookups can be chained with other lookups
  (such as :lookup:`exact`, :lookup:`gt`, :lookup:`lt`, etc.). For example:
  ``Entry.objects.filter(pub_date__month__gt=6)``.

* Time lookups (hour, minute, second) are now supported by
  :class:`~django.db.models.TimeField` for all database backends. Support for
  backends other than SQLite was added but undocumented in Django 1.7.

* You can specify the ``output_field`` parameter of the
  :class:`~django.db.models.Avg` aggregate in order to aggregate over
  non-numeric columns, such as ``DurationField``.

* Added the :lookup:`date` lookup to :class:`~django.db.models.DateTimeField`
  to allow querying the field by only the date portion.

* Added the :class:`~django.db.models.functions.Greatest` and
  :class:`~django.db.models.functions.Least` database functions.

* Added the :class:`~django.db.models.functions.Now` database function, which
  returns the current date and time.

* :class:`~django.db.models.SlugField` now accepts an
  :attr:`~django.db.models.SlugField.allow_unicode` argument to allow Unicode
  characters in slugs.

* Added support for referencing annotations in ``QuerySet.distinct()``.

CSRF
^^^^

* The request header's name used for CSRF authentication can be customized
  with :setting:`CSRF_HEADER_NAME`.

Signals
^^^^^^^

* ...

Templates
^^^^^^^^^

* Template tags created with the :meth:`~django.template.Library.simple_tag`
  helper can now store results in a template variable by using the ``as``
  argument.

* Added a :meth:`Context.setdefault() <django.template.Context.setdefault>`
  method.

* A warning will now be logged for missing context variables. These messages
  will be logged to the :ref:`django.template <django-template-logger>` logger.

* The :ttag:`firstof` template tag supports storing the output in a variable
  using 'as'.

* :meth:`Context.update() <django.template.Context.update>` can now be used as
  a context manager.

* Django template loaders can now extend templates recursively.

* The debug page template postmortem now include output from each engine that
  is installed.

* :ref:`Debug page integration <template-debug-integration>` for custom
  template engines was added.

* The :class:`~django.template.backends.django.DjangoTemplates` backend gained
  the ability to register libraries and builtins explicitly through the
  template :setting:`OPTIONS <TEMPLATES-OPTIONS>`.

* The ``timesince`` and ``timeuntil`` filters were improved to deal with leap
  years when given large time spans.

* The ``include`` tag now caches parsed templates objects during template
  rendering, speeding up reuse in places such as for loops.

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

* Unless :attr:`HttpResponse.reason_phrase
  <django.http.HttpResponse.reason_phrase>` is explicitly set, it now is
  determined by the current value of :attr:`HttpResponse.status_code
  <django.http.HttpResponse.status_code>`. Modifying the value of
  ``status_code`` outside of the constructor will also modify the value of
  ``reason_phrase``.

* The debug view now shows details of chained exceptions on Python 3.

* The default 40x error views now accept a second positional parameter, the
  exception that triggered the view.

* View error handlers now support
  :class:`~django.template.response.TemplateResponse`, commonly used with
  class-based views.

* Exceptions raised by the ``render()`` method are now passed to the
  ``process_exception()`` method of each middleware.

* Request middleware can now set :attr:`HttpRequest.urlconf
  <django.http.HttpRequest.urlconf>` to ``None`` to revert any changes made
  by previous middleware and return to using the :setting:`ROOT_URLCONF`.

* The :setting:`DISALLOWED_USER_AGENTS` check in
  :class:`~django.middleware.common.CommonMiddleware` now raises a
  :class:`~django.core.exceptions.PermissionDenied` exception as opposed to
  returning an :class:`~django.http.HttpResponseForbidden` so that
  :data:`~django.conf.urls.handler403` is invoked.

* Added :meth:`HttpRequest.get_port() <django.http.HttpRequest.get_port>` to
  fetch the originating port of the request.

* Added the ``json_dumps_params`` parameter to
  :class:`~django.http.JsonResponse` to allow passing keyword arguments to the
  ``json.dumps()`` call used to generate the response.

Tests
^^^^^

* Added the :meth:`json() <django.test.Response.json>` method to test client
  responses to give access to the response body as JSON.

* Added the :meth:`~django.test.Client.force_login()` method to the test
  client. Use this method to simulate the effect of a user logging into the
  site while skipping the authentication and verification steps of
  :meth:`~django.test.Client.login()`.

URLs
^^^^

* Regular expression lookaround assertions are now allowed in URL patterns.

* The application namespace can now be set using an ``app_name`` attribute
  on the included module or object. It can also be set by passing a 2-tuple
  of (<list of patterns>, <application namespace>) as the first argument to
  :func:`~django.conf.urls.include`.

Validators
^^^^^^^^^^

* Added :func:`django.core.validators.int_list_validator` to generate
  validators of strings containing integers separated with a custom character.

* :class:`~django.core.validators.EmailValidator` now limits the length of
  domain name labels to 63 characters per :rfc:`1034`.

* Added :func:`~django.core.validators.validate_unicode_slug` to validate slugs
  that may contain Unicode characters.

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

* The PostgreSQL backend (``django.db.backends.postgresql_psycopg2``) is also
  available as ``django.db.backends.postgresql``. The old name will continue to
  be available for backwards compatibility.

Backwards incompatible changes in 1.9
=====================================

.. warning::

    In addition to the changes outlined in this section, be sure to review the
    :doc:`deprecation timeline </internals/deprecation>` 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.

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

* A couple of new tests rely on the ability of the backend to introspect column
  defaults (returning the result as ``Field.default``). You can set the
  ``can_introspect_default`` database feature to ``False`` if your backend
  doesn't implement this. You may want to review the implementation on the
  backends that Django includes for reference (:ticket:`24245`).

* Registering a global adapter or converter at the level of the DB-API module
  to handle time zone information of :class:`~datetime.datetime` values passed
  as query parameters or returned as query results on databases that don't
  support time zones is discouraged. It can conflict with other libraries.

  The recommended way to add a time zone to :class:`~datetime.datetime` values
  fetched from the database is to register a converter for ``DateTimeField``
  in ``DatabaseOperations.get_db_converters()``.

  The ``needs_datetime_string_cast`` database feature was removed. Database
  backends that set it must register a converter instead, as explained above.

* The ``DatabaseOperations.value_to_db_<type>()`` methods were renamed to
  ``adapt_<type>field_value()`` to mirror the ``convert_<type>field_value()``
  methods.

* To use the new ``date`` lookup, third-party database backends may need to
  implement the ``DatabaseOperations.datetime_cast_date_sql()`` method.

* The ``DatabaseOperations.time_extract_sql()`` method was added. It calls the
  existing ``date_extract_sql()`` method. This method is overridden by the
  SQLite backend to add time lookups (hour, minute, second) to
  :class:`~django.db.models.TimeField`, and may be needed by third-party
  database backends.

* The ``DatabaseOperations.datetime_cast_sql()`` method (not to be confused
  with ``DatabaseOperations.datetime_cast_date_sql()`` mentioned above)
  has been removed. This method served to format dates on Oracle long
  before 1.0, but hasn't been overridden by any core backend in years
  and hasn't been called anywhere in Django's code or tests.

Default settings that were tuples are now lists
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The default settings in ``django.conf.global_settings`` were a combination of
lists and tuples. All settings that were formerly tuples are now lists.

``is_usable`` attribute on template loaders is removed
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Django template loaders previously required an ``is_usable`` attribute to be
defined. If a loader was configured in the template settings and this attribute
was ``False``, the loader would be silently ignored. In practice, this was only
used by the egg loader to detect if setuptools was installed. The ``is_usable``
attribute is now removed and the egg loader instead fails at runtime if
setuptools is not installed.

Related set direct assignment
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

:ref:`Direct assignment <direct-assignment>`) used to perform a ``clear()``
followed by a call to ``add()``. This caused needlessly large data changes
and prevented using the :data:`~django.db.models.signals.m2m_changed` signal
to track individual changes in many-to-many relations.

Direct assignment now relies on the the new
:meth:`django.db.models.fields.related.RelatedManager.set()` method on
related managers which by default only processes changes between the
existing related set and the one that's newly assigned. The previous behavior
can be restored by replacing direct assignment by a call to ``set()`` with
the keyword argument ``clear=True``.

``ModelForm``, and therefore ``ModelAdmin``, internally rely on direct
assignment for many-to-many relations and as a consequence now use the new
behavior.

Filesystem-based template loaders catch more specific exceptions
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

When using the :class:`filesystem.Loader <django.template.loaders.filesystem.Loader>`
or :class:`app_directories.Loader <django.template.loaders.app_directories.Loader>`
template loaders, earlier versions of Django raised a
:exc:`~django.template.TemplateDoesNotExist` error if a template source existed
but was unreadable. This could happen under many circumstances, such as if
Django didn't have permissions to open the file, or if the template source was
a directory. Now, Django only silences the exception if the template source
does not exist. All other situations result in the original ``IOError`` being
raised.

HTTP redirects no longer forced to absolute URIs
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Relative redirects are no longer converted to absolute URIs. :rfc:`2616`
required the ``Location`` header in redirect responses to be an absolute URI,
but it has been superseded by :rfc:`7231` which allows relative URIs in
``Location``, recognizing the actual practice of user agents, almost all of
which support them.

Consequently, the expected URLs passed to ``assertRedirects`` should generally
no longer include the scheme and domain part of the URLs. For example,
``self.assertRedirects(response, 'http://testserver/some-url/')`` should be
replaced by ``self.assertRedirects(response, '/some-url/')`` (unless the
redirection specifically contained an absolute URL, of course).

Dropped support for PostgreSQL 9.0
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Upstream support for PostgreSQL 9.0 ended in September 2015. As a consequence,
Django 1.9 sets 9.1 as the minimum PostgreSQL version it officially supports.

Bulk behavior of ``add()`` method of related managers
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

To improve performance, the ``add()`` methods of the related managers created
by ``ForeignKey`` and ``GenericForeignKey`` changed from a series of
``Model.save()`` calls to a single ``QuerySet.update()`` call. The change means
that ``pre_save`` and ``post_save`` signals aren't sent anymore. You can use
the ``bulk=False`` keyword argument to revert to the previous behavior.

Template ``LoaderOrigin`` and ``StringOrigin`` are removed
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

In previous versions of Django, when a template engine was initialized with
debug as ``True``, an instance of ``django.template.loader.LoaderOrigin`` or
``django.template.base.StringOrigin`` was set as the origin attribute on the
template object. These classes have been combined into
:class:`~django.template.base.Origin` and is now always set regardless of the
engine debug setting.

.. _default-logging-changes-19:

Changes to the default logging configuration
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

To make it easier to write custom logging configurations, Django's default
logging configuration no longer defines 'django.request' and 'django.security'
loggers. Instead, it defines a single 'django' logger with two handlers:

* 'console': filtered at the ``INFO`` level and only active if ``DEBUG=True``.
* 'mail_admins': filtered at the ``ERROR`` level and only active if
  ``DEBUG=False``.

If you aren't overriding Django's default logging, you should see minimal
changes in behavior, but you might see some new logging to the ``runserver``
console, for example.

If you are overriding Django's default logging, you should check to see how
your configuration merges with the new defaults.

``HttpRequest`` details in error reporting
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

It was redundant to display the full details of the
:class:`~django.http.HttpRequest` each time it appeared as a stack frame
variable in the HTML version of the debug page and error email. Thus, the HTTP
request will now display the same standard representation as other variables
(``repr(request)``). As a result, the method
``ExceptionReporterFilter.get_request_repr()`` was removed.

The contents of the text version of the email were modified to provide a
traceback of the same structure as in the case of AJAX requests. The traceback
details are rendered by the ``ExceptionReporter.get_traceback_text()`` method.

Removal of time zone aware global adapters and converters for datetimes
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Django no longer registers global adapters and converters for managing time
zone information on :class:`~datetime.datetime` values sent to the database as
query parameters or read from the database in query results. This change
affects projects that meet all the following conditions:

* The :setting:`USE_TZ` setting is ``True``.
* The database is SQLite, MySQL, Oracle, or a third-party database that
  doesn't support time zones. In doubt, you can check the value of
  ``connection.features.supports_timezones``.
* The code queries the database outside of the ORM, typically with
  ``cursor.execute(sql, params)``.

If you're passing aware :class:`~datetime.datetime` parameters to such
queries, you should turn them into naive datetimes in UTC::

    from django.utils import timezone
    param = timezone.make_naive(param, timezone.utc)

If you fail to do so, Django 1.9 and 2.0 will perform the conversion like
earlier versions but emit a deprecation warning. Django 2.0 won't perform any
conversion, which may result in data corruption.

If you're reading :class:`~datetime.datetime` values from the results, they
will be naive instead of aware. You can compensate as follows::

    from django.utils import timezone
    value = timezone.make_aware(value, timezone.utc)

You don't need any of this if you're querying the database through the ORM,
even if you're using :meth:`raw() <django.db.models.query.QuerySet.raw>`
queries. The ORM takes care of managing time zone information.

Template tag modules are imported when templates are configured
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The :class:`~django.template.backends.django.DjangoTemplates` backend now
performs discovery on installed template tag modules when instantiated. This
update enables libraries to be provided explicitly via the ``'libraries'``
key of :setting:`OPTIONS <TEMPLATES-OPTIONS>` when defining a
:class:`~django.template.backends.django.DjangoTemplates` backend. Import
or syntax errors in template tag modules now fail early at instantiation time
rather than when a template with a :ttag:`{% load %}<load>` tag is first
compiled.

``django.template.base.add_to_builtins()`` is removed
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Although it was a private API, projects commonly used ``add_to_builtins()`` to
make template tags and filters available without using the
:ttag:`{% load %}<load>` tag. This API has been formalized. Projects should now
define built-in libraries via the ``'builtins'`` key of :setting:`OPTIONS
<TEMPLATES-OPTIONS>` when defining a
:class:`~django.template.backends.django.DjangoTemplates` backend.

.. _simple-tag-conditional-escape-fix:

``simple_tag`` now wraps tag output in ``conditional_escape``
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

In general, template tags do not autoescape their contents, and this behavior is
:ref:`documented <tags-auto-escaping>`. For tags like
:class:`~django.template.Library.inclusion_tag`, this is not a problem because
the included template will perform autoescaping. For
:class:`~django.template.Library.assignment_tag`, the output will be escaped
when it is used as a variable in the template.

For the intended use cases of :class:`~django.template.Library.simple_tag`,
however, it is very easy to end up with incorrect HTML and possibly an XSS
exploit. For example::

    @register.simple_tag(takes_context=True)
    def greeting(context):
        return "Hello {0}!".format(context['request'].user.first_name)

In older versions of Django, this will be an XSS issue because
``user.first_name`` is not escaped.

In Django 1.9, this is fixed: if the template context has ``autoescape=True``
set (the default), then ``simple_tag`` will wrap the output of the tag function
with :func:`~django.utils.html.conditional_escape`.

To fix your ``simple_tag``\s, it is best to apply the following practices:

* Any code that generates HTML should use either the template system or
  :func:`~django.utils.html.format_html`.

* If the output of a ``simple_tag`` needs escaping, use
  :func:`~django.utils.html.escape` or
  :func:`~django.utils.html.conditional_escape`.

* If you are absolutely certain that you are outputting HTML from a trusted
  source (e.g. a CMS field that stores HTML entered by admins), you can mark it
  as such using :func:`~django.utils.safestring.mark_safe`.

Tags that follow these rules will be correct and safe whether they are run on
Django 1.9+ or earlier.

``Paginator.page_range``
~~~~~~~~~~~~~~~~~~~~~~~~

:attr:`Paginator.page_range <django.core.paginator.Paginator.page_range>` is
now an iterator instead of a list.

In versions of Django previous to 1.8, ``Paginator.page_range`` returned a
``list`` in Python 2 and a ``range`` in Python 3. Django 1.8 consistently
returned a list, but an iterator is more efficient.

Existing code that depends on ``list`` specific features, such as indexing,
can be ported by converting the iterator into a ``list`` using ``list()``.

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

* CSS and images in ``contrib.admin`` to support Internet Explorer 6 & 7 have
  been removed as these browsers have reached end-of-life.

* The jQuery static files in ``contrib.admin`` have been moved into a
  ``vendor/jquery`` subdirectory.

* The text displayed for null columns in the admin changelist ``list_display``
  cells has changed from ``(None)`` (or its translated equivalent) to ``-``.

* ``django.http.responses.REASON_PHRASES`` and
  ``django.core.handlers.wsgi.STATUS_CODE_TEXT`` have been removed. Use
  Python's stdlib instead: :data:`http.client.responses` for Python 3 and
  `httplib.responses`_ for Python 2.

  .. _`httplib.responses`: https://docs.python.org/2/library/httplib.html#httplib.responses

* ``ValuesQuerySet`` and ``ValuesListQuerySet`` have been removed.

* The ``admin/base.html`` template no longer sets
  ``window.__admin_media_prefix__`` or ``window.__admin_utc_offset__``. Image
  references in JavaScript that used that value to construct absolute URLs have
  been moved to CSS for easier customization. The UTC offset is stored on a
  data attribute of the ``<body>`` tag.

* ``CommaSeparatedIntegerField`` validation has been refined to forbid values
  like ``','``, ``',1'``, and ``'1,,2'``.

* Form initialization was moved from the :meth:`ProcessFormView.get()
  <django.views.generic.edit.ProcessFormView.get>` method to the new
  :meth:`FormMixin.get_context_data()
  <django.views.generic.edit.FormMixin.get_context_data>` method. This may be
  backwards incompatible if you have overridden the ``get_context_data()``
  method without calling ``super()``.

* Support for PostGIS 1.5 has been dropped.

* The ``django.contrib.sites.models.Site.domain`` field was changed to be
  :attr:`~django.db.models.Field.unique`.

* In order to enforce test isolation, database queries are not allowed
  by default in :class:`~django.test.SimpleTestCase` tests anymore. You
  can disable this behavior by setting the
  :attr:`~django.test.SimpleTestCase.allow_database_queries` class attribute
  to ``True`` on your test class.

* :attr:`ResolverMatch.app_name
  <django.core.urlresolvers.ResolverMatch.app_name>` was changed to contain
  the full namespace path in the case of nested namespaces. For consistency
  with :attr:`ResolverMatch.namespace
  <django.core.urlresolvers.ResolverMatch.namespace>`, the empty value is now
  an empty string instead of ``None``.

* For security hardening, session keys must be at least 8 characters.

* Private function ``django.utils.functional.total_ordering()`` has been
  removed. It contained a workaround for a ``functools.total_ordering()`` bug
  in Python versions older than 2.7.3.
* XML serialization (either through :djadmin:`dumpdata` or the syndication
  framework) used to output any characters it received. Now if the content to
  be serialized contains any control characters not allowed in the XML 1.0
  standard, the serialization will fail with a :exc:`ValueError`.

* :class:`~django.forms.CharField` now strips input of leading and trailing
  whitespace by default. This can be disabled by setting the new
  :attr:`~django.forms.CharField.strip` argument to ``False``.

* Template text that is translated and uses two or more consecutive percent
  signs, e.g. ``"%%"``, may have a new `msgid` after ``makemessages`` is run
  (most likely the translation will be marked fuzzy). The new ``msgid`` will be
  marked ``"#, python-format"``.

* If neither :attr:`request.current_app <django.http.HttpRequest.current_app>`
  nor :class:`Context.current_app <django.template.Context>` are set, the
  :ttag:`url` template tag will now use the namespace of the current request.
  Set ``request.current_app`` to ``None`` if you don't want to use a namespace
  hint.

.. _deprecated-features-1.9:

Features deprecated in 1.9
==========================

``assignment_tag()``
~~~~~~~~~~~~~~~~~~~~

Django 1.4 added the ``assignment_tag`` helper to ease the creation of
template tags that store results in a template variable. The
:meth:`~django.template.Library.simple_tag` helper has gained this same
ability, making the ``assignment_tag`` obsolete. Tags that use
``assignment_tag`` should be updated to use ``simple_tag``.

``{% cycle %}`` syntax with comma-separated arguments
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The :ttag:`cycle` tag supports an inferior old syntax from previous Django
versions:

.. code-block:: html+django

    {% cycle row1,row2,row3 %}

Its parsing caused bugs with the current syntax, so support for the old syntax
will be removed in Django 2.0 following an accelerated deprecation.

``ForeignKey`` and ``OneToOneField`` ``on_delete`` argument
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

In order to increase awareness about cascading model deletion, the
``on_delete`` argument of ``ForeignKey`` and ``OneToOneField`` will be required
in Django 2.0.

Update models and existing migrations to explicitly set the argument. Since the
default is ``models.CASCADE``, add ``on_delete=models.CASCADE`` to all
``ForeignKey`` and ``OneToOneField``\s that don't use a different option. You
can also pass it as the second positional argument if you don't care about
compatibility with older versions of Django.

``Field.rel`` changes
~~~~~~~~~~~~~~~~~~~~~

``Field.rel`` and its methods and attributes have changed to match the related
fields API. The ``Field.rel`` attribute is renamed to ``remote_field`` and many
of its methods and attributes are either changed or renamed.

The aim of these changes is to provide a documented API for relation fields.

``GeoManager`` and ``GeoQuerySet`` custom methods
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

All custom ``GeoQuerySet`` methods (``area()``, ``distance()``, ``gml()``, ...)
have been replaced by equivalent geographic expressions in annotations (see in
new features). Hence the need to set a custom ``GeoManager`` to GIS-enabled
models is now obsolete. As soon as your code doesn't call any of the deprecated
methods, you can simply remove the ``objects = GeoManager()`` lines from your
models.

Template loader APIs have changed
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Django template loaders have been updated to allow recursive template
extending. This change necessitated a new template loader API. The old
``load_template()`` and ``load_template_sources()`` methods are now deprecated.
Details about the new API can be found :ref:`in the template loader
documentation <custom-template-loaders>`.

Passing a 3-tuple or an ``app_name`` to :func:`~django.conf.urls.include()`
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The instance namespace part of passing a tuple as the first argument has been
replaced by passing the ``namespace`` argument to ``include()``. The
``app_name`` argument to ``include()`` has been replaced by passing a 2-tuple,
or passing an object or module with an ``app_name`` attribute.

If the ``app_name`` is set in this new way, the ``namespace`` argument is no
longer required. It will default to the value of ``app_name``.

This change also means that the old way of including an ``AdminSite`` instance
is deprecated. Instead, pass ``admin.site.urls`` directly to
:func:`~django.conf.urls.url()`:

.. snippet::
    :filename: urls.py

    from django.conf.urls import url
    from django.contrib import admin

    urlpatterns = [
        url(r'^admin/', admin.site.urls),
    ]

URL application namespace required if setting an instance namespace
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

In the past, an instance namespace without an application namespace
would serve the same purpose as the application namespace, but it was
impossible to reverse the patterns if there was an application namespace
with the same name. Includes that specify an instance namespace require that
the included URLconf sets an application namespace.

``current_app`` parameter to ``contrib.auth`` views
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

All views in ``django.contrib.auth.views`` have the following structure::

    def view(request, ..., current_app=None, ...):

        ...

        if current_app is not None:
            request.current_app = current_app

        return TemplateResponse(request, template_name, context)

As of Django 1.8, ``current_app`` is set on the ``request`` object. For
consistency, these views will require the caller to set ``current_app`` on the
``request`` instead of passing it in a separate argument.

``django.contrib.gis.geoip``
~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The :mod:`django.contrib.gis.geoip2` module supersedes
``django.contrib.gis.geoip``. The new module provides a similar API except that
it doesn't provide the legacy GeoIP-Python API compatibility methods.

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

* The ``weak`` argument to ``django.dispatch.signals.Signal.disconnect()`` has
  been deprecated as it has no effect.

* The ``check_aggregate_support()`` method of
  ``django.db.backends.base.BaseDatabaseOperations`` has been deprecated and
  will be removed in Django 2.0. The more general ``check_expression_support()``
  should be used instead.

* ``django.forms.extras`` is deprecated. You can find
  :class:`~django.forms.SelectDateWidget` in ``django.forms.widgets``
  (or simply ``django.forms``) instead.

* Private API ``django.db.models.fields.add_lazy_relation()`` is deprecated.

* The ``django.contrib.auth.tests.utils.skipIfCustomUser()`` decorator is
  deprecated. With the test discovery changes in Django 1.6, the tests for
  ``django.contrib`` apps are no longer run as part of the user's project.
  Therefore, the ``@skipIfCustomUser`` decorator is no longer needed to
  decorate tests in ``django.contrib.auth``.

* If you customized some :ref:`error handlers <error-views>`, the view
  signatures with only one request parameter are deprecated. The views should
  now also accept a second ``exception`` positional parameter.

* The ``django.utils.feedgenerator.Atom1Feed.mime_type`` and
  ``django.utils.feedgenerator.RssFeed.mime_type`` attributes are deprecated in
  favor of ``content_type``.

* :class:`~django.core.signing.Signer` now issues a warning if an invalid
  separator is used. This will become an exception in Django 1.10.

* ``django.db.models.Field._get_val_from_obj()`` is deprecated in favor of
  ``Field.value_from_object()``.

* ``django.template.loaders.eggs.Loader`` is deprecated as distributing
  applications as eggs is not recommended.

* The ``callable_obj`` keyword argument to
  ``SimpleTestCase.assertRaisesMessage()`` is deprecated. Pass the callable as
  a positional argument instead.

.. removed-features-1.9:

Features removed in 1.9
=======================

These features have reached the end of their deprecation cycle and so have been
removed in Django 1.9 (please see the :ref:`deprecation timeline
<deprecation-removed-in-1.9>` for more details):

* ``django.utils.dictconfig`` is removed.

* ``django.utils.importlib`` is removed.

* ``django.utils.tzinfo`` is removed.

* ``django.utils.unittest`` is removed.

* The ``syncdb`` command is removed.

* ``django.db.models.signals.pre_syncdb`` and
  ``django.db.models.signals.post_syncdb`` is removed.

* Support for ``allow_syncdb`` on database routers is removed.

* The legacy method of syncing apps without migrations is removed,
  and migrations are compulsory for all apps. This includes automatic
  loading of ``initial_data`` fixtures and support for initial SQL data.

* All models need to be defined inside an installed application or declare an
  explicit :attr:`~django.db.models.Options.app_label`. Furthermore, it isn't
  possible to import them before their application is loaded. In particular, it
  isn't possible to import models inside the root package of an application.

* The model and form ``IPAddressField`` is removed. A stub field remains for
  compatibility with historical migrations.

* ``AppCommand.handle_app()`` is no longer be supported.

* ``RequestSite`` and ``get_current_site()`` are no longer importable from
  ``django.contrib.sites.models``.

* FastCGI support via the ``runfcgi`` management command is removed.

* ``django.utils.datastructures.SortedDict`` is removed.

* ``ModelAdmin.declared_fieldsets`` is removed.

* The ``util`` modules that provided backwards compatibility are removed:

  * ``django.contrib.admin.util``
  * ``django.contrib.gis.db.backends.util``
  * ``django.db.backends.util``
  * ``django.forms.util``

* ``ModelAdmin.get_formsets`` is removed.

* The backward compatible shims introduced to rename the
  ``BaseMemcachedCache._get_memcache_timeout()`` method to
  ``get_backend_timeout()`` is removed.

* The ``--natural`` and ``-n`` options for :djadmin:`dumpdata` are removed.

* The ``use_natural_keys`` argument for ``serializers.serialize()`` is removed.

* Private API ``django.forms.forms.get_declared_fields()`` is removed.

* The ability to use a ``SplitDateTimeWidget`` with ``DateTimeField`` is
  removed.

* The ``WSGIRequest.REQUEST`` property is removed.

* The class ``django.utils.datastructures.MergeDict`` is removed.

* The ``zh-cn`` and ``zh-tw`` language codes are removed.

* The internal ``django.utils.functional.memoize()`` is removed.

* ``django.core.cache.get_cache`` is removed.

* ``django.db.models.loading`` is removed.

* Passing callable arguments to querysets is no longer possible.

* ``BaseCommand.requires_model_validation`` is removed in favor of
  ``requires_system_checks``. Admin validators is replaced by admin checks.

* The ``ModelAdmin.validator_class`` and ``default_validator_class`` attributes
  are removed.

* ``ModelAdmin.validate()`` is removed.

* ``django.db.backends.DatabaseValidation.validate_field`` is removed in
  favor of the ``check_field`` method.

* The ``validate`` management command is removed.

* ``django.utils.module_loading.import_by_path`` is removed in favor of
  ``django.utils.module_loading.import_string``.

* ``ssi`` and ``url`` template tags are removed from the ``future`` template
  tag library.

* ``django.utils.text.javascript_quote()`` is removed.

* Database test settings as independent entries in the database settings,
  prefixed by ``TEST_``, are no longer supported.

* The `cache_choices` option to :class:`~django.forms.ModelChoiceField` and
  :class:`~django.forms.ModelMultipleChoiceField` is removed.

* The default value of the
  :attr:`RedirectView.permanent <django.views.generic.base.RedirectView.permanent>`
  attribute has changed from ``True`` to ``False``.

* ``django.contrib.sitemaps.FlatPageSitemap`` is removed in favor of
  ``django.contrib.flatpages.sitemaps.FlatPageSitemap``.

* Private API ``django.test.utils.TestTemplateLoader`` is removed.

* The ``django.contrib.contenttypes.generic`` module is removed.