============================================
Django 4.0 release notes - UNDER DEVELOPMENT
============================================

*Expected December 2021*

Welcome to Django 4.0!

These release notes cover the :ref:`new features <whats-new-4.0>`, as well as
some :ref:`backwards incompatible changes <backwards-incompatible-4.0>` you'll
want to be aware of when upgrading from Django 3.2 or earlier. We've
:ref:`begun the deprecation process for some features
<deprecated-features-4.0>`.

See the :doc:`/howto/upgrade-version` guide if you're updating an existing
project.

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

Django 4.0 supports Python 3.8, 3.9, and 3.10. We **highly recommend** and only
officially support the latest release of each series.

.. _whats-new-4.0:

What's new in Django 4.0
========================

Minor features
--------------

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

* The ``admin/base.html`` template now has a new block ``header`` which
  contains the admin site header.

:mod:`django.contrib.admindocs`
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

* ...

:mod:`django.contrib.auth`
~~~~~~~~~~~~~~~~~~~~~~~~~~

* The default iteration count for the PBKDF2 password hasher is increased from
  260,000 to 320,000.

:mod:`django.contrib.contenttypes`
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

* ...

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

* ...

:mod:`django.contrib.messages`
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

* ...

:mod:`django.contrib.postgres`
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

* ...

:mod:`django.contrib.redirects`
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

* ...

:mod:`django.contrib.sessions`
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

* ...

:mod:`django.contrib.sitemaps`
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

* ...

:mod:`django.contrib.sites`
~~~~~~~~~~~~~~~~~~~~~~~~~~~

* ...

:mod:`django.contrib.staticfiles`
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

* ...

:mod:`django.contrib.syndication`
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

* ...

Cache
~~~~~

* ...

CSRF
~~~~

* ...

Decorators
~~~~~~~~~~

* ...

Email
~~~~~

* ...

Error Reporting
~~~~~~~~~~~~~~~

* ...

File Storage
~~~~~~~~~~~~

* ...

File Uploads
~~~~~~~~~~~~

* ...

Forms
~~~~~

* ...

Generic Views
~~~~~~~~~~~~~

* ...

Internationalization
~~~~~~~~~~~~~~~~~~~~

* ...

Logging
~~~~~~~

* ...

Management Commands
~~~~~~~~~~~~~~~~~~~

* The :djadmin:`runserver` management command now supports the
  :option:`--skip-checks` option.

Migrations
~~~~~~~~~~

* ...

Models
~~~~~~

* ...

Requests and Responses
~~~~~~~~~~~~~~~~~~~~~~

* ...

Security
~~~~~~~~

* ...

Serialization
~~~~~~~~~~~~~

* ...

Signals
~~~~~~~

* ...

Templates
~~~~~~~~~

* ...

Tests
~~~~~

* ...

URLs
~~~~

* ...

Utilities
~~~~~~~~~

* ...

Validators
~~~~~~~~~~

* ...

.. _backwards-incompatible-4.0:

Backwards incompatible changes in 4.0
=====================================

Database backend API
--------------------

This section describes changes that may be needed in third-party database
backends.

* ...

:mod:`django.contrib.gis`
-------------------------

* Support for PostGIS 2.3 is removed.

Dropped support for PostgreSQL 9.6
----------------------------------

Upstream support for PostgreSQL 9.6 ends in November 2021. Django 4.0 supports
PostgreSQL 10 and higher.

Miscellaneous
-------------

* ...

.. _deprecated-features-4.0:

Features deprecated in 4.0
==========================

Miscellaneous
-------------

* ...

Features removed in 4.0
=======================

These features have reached the end of their deprecation cycle and are removed
in Django 4.0.

See :ref:`deprecated-features-3.0` for details on these changes, including how
to remove usage of these features.

* ``django.utils.http.urlquote()``, ``urlquote_plus()``, ``urlunquote()``, and
  ``urlunquote_plus()`` are removed.

* ``django.utils.encoding.force_text()`` and ``smart_text()`` are removed.

* ``django.utils.translation.ugettext()``, ``ugettext_lazy()``,
  ``ugettext_noop()``, ``ungettext()``, and ``ungettext_lazy()`` are removed.

* ``django.views.i18n.set_language()`` doesn't set the user language in
  ``request.session`` (key ``_language``).

* ``alias=None`` is required in the signature of
  ``django.db.models.Expression.get_group_by_cols()`` subclasses.

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

* ``django.utils.http.is_safe_url()`` is removed.

See :ref:`deprecated-features-3.1` for details on these changes, including how
to remove usage of these features.

* The ``PASSWORD_RESET_TIMEOUT_DAYS`` setting is removed.

* The :lookup:`isnull` lookup no longer allows using non-boolean values as the
  right-hand side.

* The ``django.db.models.query_utils.InvalidQuery`` exception class is removed.

* The ``django-admin.py`` entry point is removed.

* The ``HttpRequest.is_ajax()`` method is removed.

* Support for the pre-Django 3.1 encoding format of cookies values used by
  ``django.contrib.messages.storage.cookie.CookieStorage`` is removed.

* Support for the pre-Django 3.1 password reset tokens in the admin site (that
  use the SHA-1 hashing algorithm) is removed.

* Support for the pre-Django 3.1 encoding format of sessions is removed.

* Support for the pre-Django 3.1 ``django.core.signing.Signer`` signatures
  (encoded with the SHA-1 algorithm) is removed.

* Support for the pre-Django 3.1 ``django.core.signing.dumps()`` signatures
  (encoded with the SHA-1 algorithm) in ``django.core.signing.loads()`` is
  removed.

* Support for the pre-Django 3.1 user sessions (that use the SHA-1 algorithm)
  is removed.

* The ``get_request`` argument for
  ``django.utils.deprecation.MiddlewareMixin.__init__()`` is required and
  doesn't accept ``None``.

* The ``providing_args`` argument for ``django.dispatch.Signal`` is removed.

* The ``length`` argument for ``django.utils.crypto.get_random_string()`` is
  required.

* The ``list`` message for ``ModelMultipleChoiceField`` is removed.

* Support for passing raw column aliases to ``QuerySet.order_by()`` is removed.

* The ``NullBooleanField`` model field is removed, except for support in
  historical migrations.

* ``django.conf.urls.url()`` is removed.

* The ``django.contrib.postgres.fields.JSONField`` model field is removed,
  except for support in historical migrations.

* ``django.contrib.postgres.fields.jsonb.KeyTransform`` and
  ``django.contrib.postgres.fields.jsonb.KeyTextTransform`` are removed.

* ``django.contrib.postgres.forms.JSONField`` is removed.

* The ``{% ifequal %}`` and ``{% ifnotequal %}`` template tags are removed.

* The ``DEFAULT_HASHING_ALGORITHM`` transitional setting is removed.
