============================================
Django 5.1 release notes - UNDER DEVELOPMENT
============================================

*Expected August 2024*

Welcome to Django 5.1!

These release notes cover the :ref:`new features <whats-new-5.1>`, as well as
some :ref:`backwards incompatible changes <backwards-incompatible-5.1>` you
should be aware of when upgrading from Django 5.0 or earlier. We've
:ref:`begun the deprecation process for some features
<deprecated-features-5.1>`.

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

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

Django 5.1 supports Python 3.10, 3.11, and 3.12. We **highly recommend** and
only officially support the latest release of each series.

.. _whats-new-5.1:

What's new in Django 5.1
========================

``{% query_string %}`` template tag
-----------------------------------

Django 5.1 introduces the :ttag:`{% query_string %} <query_string>` template
tag, simplifying the modification of query parameters in URLs, making it easier
to generate links that maintain existing query parameters while adding or
changing specific ones.

For instance, navigating pagination and query strings in templates can be
cumbersome. Consider this template fragment that dynamically generates a URL
for navigating to the next page within a paginated view:

.. code-block:: html+django

    {# Linebreaks added for readability, this should be one, long line. #}
    <a href="?{% for key, values in request.GET.iterlists %}
      {% if key != "page" %}
        {% for value in values %}
          {{ key }}={{ value }}&amp;
        {% endfor %}
      {% endif %}
    {% endfor %}page={{ page.next_page_number }}">Next page</a>

When switching to using this new template tag, the above magically becomes:

.. code-block:: html+django

    <a href="{% query_string page=page.next_page_number %}">Next page</a>

PostgreSQL Connection Pools
---------------------------

Django 5.1 also introduces :ref:`connection pool <postgresql-pool>` support for
PostgreSQL. As the time to establish a new connection can be relatively long,
keeping connections open can reduce latency.

To use a connection pool with `psycopg`_, you can set the ``"pool"`` option
inside :setting:`OPTIONS` to be a dict to be passed to
:class:`~psycopg:psycopg_pool.ConnectionPool`, or to ``True`` to use the
``ConnectionPool`` defaults::

    DATABASES = {
        "default": {
            "ENGINE": "django.db.backends.postgresql",
            # ...
            "OPTIONS": {
                "pool": {
                    "min_size": 2,
                    "max_size": 4,
                    "timeout": 10,
                }
            },
        },
    }

.. _psycopg: https://www.psycopg.org/

Middleware to require authentication by default
-----------------------------------------------

The new :class:`~django.contrib.auth.middleware.LoginRequiredMiddleware`
redirects all unauthenticated requests to a login page. Views can allow
unauthenticated requests by using the new
:func:`~django.contrib.auth.decorators.login_not_required` decorator.

The :class:`~django.contrib.auth.middleware.LoginRequiredMiddleware` respects
the ``login_url`` and ``redirect_field_name`` values set via the
:func:`~.django.contrib.auth.decorators.login_required` decorator, but does not
support setting ``login_url`` or ``redirect_field_name`` via the
:class:`~django.contrib.auth.mixins.LoginRequiredMixin`.

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

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

* :attr:`.ModelAdmin.list_display` now supports using ``__`` lookups to list
  fields from related models.

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

* The default iteration count for the PBKDF2 password hasher is increased from
  720,000 to 870,000.

* The default ``parallelism`` of the ``ScryptPasswordHasher`` is 
  increased from 1 to 5, to follow OWASP recommendations.

* :class:`~django.contrib.auth.forms.BaseUserCreationForm` and
  :class:`~django.contrib.auth.forms.AdminPasswordChangeForm` now support
  disabling password-based authentication by setting an unusable password on
  form save. This is now available in the admin when visiting the user creation
  and password change pages.

* :func:`~.django.contrib.auth.decorators.login_required`,
  :func:`~.django.contrib.auth.decorators.permission_required`, and
  :func:`~.django.contrib.auth.decorators.user_passes_test` decorators now
  support wrapping asynchronous view functions.

* ``ReadOnlyPasswordHashWidget`` now includes a button to reset the user's
  password, which replaces the link previously embedded in the
  ``ReadOnlyPasswordHashField``'s help text, improving the overall
  accessibility of the
  :class:`~django.contrib.auth.forms.UserChangeForm`.

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

* :class:`~django.contrib.gis.db.models.functions.BoundingCircle` is now
  supported on SpatiaLite 5.1+.

* :class:`~django.contrib.gis.db.models.Collect` is now supported on MySQL
  8.0.24+.

* :class:`~django.contrib.gis.geoip2.GeoIP2` now allows querying using
  :class:`ipaddress.IPv4Address` or :class:`ipaddress.IPv6Address` objects.

* :meth:`.GeoIP2.country` now exposes the ``continent_code``,
  ``continent_name``, and ``is_in_european_union`` values.

* :meth:`.GeoIP2.city` now exposes the ``accuracy_radius`` and ``region_name``
  values. In addition, the ``dma_code`` and ``region`` values are now exposed
  as ``metro_code`` and ``region_code``, but the previous keys are also
  retained for backward compatibility.

* :class:`~django.contrib.gis.measure.Area` now supports the ``ha`` unit.

* The new :attr:`.OGRGeometry.is_3d` attribute allows checking if a geometry
  has a ``Z`` coordinate dimension.

* The new :meth:`.OGRGeometry.set_3d` method allows addition and removal of the
  ``Z`` coordinate dimension.

* :class:`~django.contrib.gis.gdal.OGRGeometry`,
  :class:`~django.contrib.gis.gdal.Point`,
  :class:`~django.contrib.gis.gdal.LineString`,
  :class:`~django.contrib.gis.gdal.Polygon`, and
  :class:`~django.contrib.gis.gdal.GeometryCollection` and its subclasses now
  support measured geometries via the new :attr:`.OGRGeometry.is_measured` and
  ``m`` properties, and the :meth:`.OGRGeometry.set_measured` method.

* :attr:`.OGRGeometry.centroid` is now available on all supported geometry
  types.

* :class:`FromWKB() <django.contrib.gis.db.models.functions.FromWKB>` and
  :class:`FromWKT() <django.contrib.gis.db.models.functions.FromWKT>` functions
  now support the optional ``srid`` argument (except for Oracle where it is
  ignored).

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

* :class:`~django.contrib.postgres.indexes.BTreeIndex` now supports the
  ``deduplicate_items`` parameter.

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

* :class:`django.contrib.sessions.backends.cached_db.SessionStore` now handles
  exceptions when storing session information in the cache, logging proper
  error messages with their traceback via the newly added
  :ref:`sessions logger <django-contrib-sessions-logger>`.

* :class:`django.contrib.sessions.backends.base.SessionBase` and all built-in
  session engines now provide async API. The new asynchronous methods all have
  ``a`` prefixed names, e.g. ``aget()``, ``akeys()``, or ``acycle_key()``.

Database backends
~~~~~~~~~~~~~~~~~

* ``"init_command"`` option is now supported in :setting:`OPTIONS` on SQLite
  to allow specifying :ref:`pragma options <sqlite-init-command>` to set upon
  connection.

* ``"transaction_mode"`` option is now supported in :setting:`OPTIONS` on
  SQLite to allow specifying the :ref:`sqlite-transaction-behavior`.

* ``"pool"`` option is now supported in :setting:`OPTIONS` on PostgreSQL to
  allow using :ref:`connection pools <postgresql-pool>`.

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

* In order to improve accessibility, the technical 404 and 500 error pages now
  use HTML landmark elements for the header, footer, and main content areas.

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

* The :attr:`~django.core.files.storage.FileSystemStorage.allow_overwrite`
  parameter of :class:`~django.core.files.storage.FileSystemStorage` now allows
  saving new files over existing ones.

Forms
~~~~~

* In order to improve accessibility and enable screen readers to associate
  fieldsets with their help text, the form fieldset now includes the
  ``aria-describedby`` HTML attribute.

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

* The :djadmin:`makemigrations` command now displays meaningful symbols for
  each operation to highlight :class:`operation categories
  <django.db.migrations.operations.base.OperationCategory>`.

Migrations
~~~~~~~~~~

* The new ``Operation.category`` attribute allows specifying an
  :class:`operation category
  <django.db.migrations.operations.base.OperationCategory>` used by the
  :djadmin:`makemigrations` to display a meaningful symbol for the operation.

Models
~~~~~~

* :meth:`.QuerySet.explain` now supports the ``generic_plan`` option on
  PostgreSQL 16+.

* :class:`~django.db.models.expressions.RowRange` now accepts positive integers
  for the ``start`` argument and negative integers for the ``end`` argument.

* The new ``exclusion`` argument of
  :class:`~django.db.models.expressions.RowRange` and
  :class:`~django.db.models.expressions.ValueRange` allows excluding rows,
  groups, and ties from the window frames.

* :meth:`.QuerySet.order_by` now supports ordering by annotation transforms
  such as ``JSONObject`` keys and ``ArrayAgg`` indices.

* :class:`F() <django.db.models.F>` and :class:`OuterRef()
  <django.db.models.OuterRef>` expressions that output
  :class:`~django.db.models.CharField`, :class:`~django.db.models.EmailField`,
  :class:`~django.db.models.SlugField`, :class:`~django.db.models.URLField`,
  :class:`~django.db.models.TextField`, or
  :class:`~django.contrib.postgres.fields.ArrayField` can now be :ref:`sliced
  <slicing-using-f>`.

* The new ``from_queryset`` argument of :meth:`.Model.refresh_from_db` and
  :meth:`.Model.arefresh_from_db`  allows customizing the queryset used to
  reload a model's value. This can be used to lock the row before reloading or
  to select related objects.

* The new :attr:`.Expression.constraint_validation_compatible` attribute allows
  specifying that the expression should be ignored during a constraint
  validation.

Templates
~~~~~~~~~

* Custom tags may now set extra data on the ``Parser`` object that will later
  be made available on the ``Template`` instance. Such data may be used, for
  example, by the template loader, or other template clients.

* :ref:`Template engines <field-checking>` now implement a ``check()`` method
  that is already registered with the check framework.

Tests
~~~~~

* :meth:`~django.test.SimpleTestCase.assertContains`,
  :meth:`~django.test.SimpleTestCase.assertNotContains`, and
  :meth:`~django.test.SimpleTestCase.assertInHTML` assertions now add haystacks
  to assertion error messages.

* The :class:`~django.test.RequestFactory`,
  :class:`~django.test.AsyncRequestFactory`, :class:`~django.test.Client`, and
  :class:`~django.test.AsyncClient` classes now support the ``query_params``
  parameter, which accepts a dictionary of query string keys and values. This
  allows setting query strings on any HTTP methods more easily.

  .. code-block:: python

     self.client.post("/items/1", query_params={"action": "delete"})
     await self.async_client.post("/items/1", query_params={"action": "delete"})

* The new :meth:`.SimpleTestCase.assertNotInHTML` assertion allows testing that
  an HTML fragment is not contained in the given HTML haystack.

* In order to enforce test isolation, database connections inside threads are
  no longer allowed in :class:`~django.test.SimpleTestCase`.

Validators
~~~~~~~~~~

* The new :class:`~django.core.validators.DomainNameValidator` validates domain
  names, including internationalized domain names. The new
  :func:`~django.core.validators.validate_domain_name` function returns an
  instance of :class:`~django.core.validators.DomainNameValidator`.

.. _backwards-incompatible-5.1:

Backwards incompatible changes in 5.1
=====================================

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

* Support for PostGIS 2.5 is removed.

* Support for PROJ < 6 is removed.

* Support for GDAL 2.4 is removed.

* :class:`~django.contrib.gis.geoip2.GeoIP2` no longer opens both city and
  country databases when a directory path is provided, preferring the city
  database, if it is available. The country database is a subset of the city
  database and both are not typically needed. If you require use of the country
  database when in the same directory as the city database, explicitly pass the
  country database path to the constructor.

Dropped support for MariaDB 10.4
--------------------------------

Upstream support for MariaDB 10.4 ends in June 2024. Django 5.1 supports
MariaDB 10.5 and higher.

Dropped support for PostgreSQL 12
---------------------------------

Upstream support for PostgreSQL 12 ends in November 2024. Django 5.1 supports
PostgreSQL 13 and higher.

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

* In order to improve accessibility, the admin's changelist filter is now
  rendered in a ``<nav>`` tag instead of a ``<div>``.

* In order to improve accessibility, the admin's footer is now rendered in
  a ``<footer>`` tag instead of a ``<div>``, and also moved below the
  ``<div id="main">`` element.

* In order to improve accessibility, the expandable widget used for
  :attr:`ModelAdmin.fieldsets <django.contrib.admin.ModelAdmin.fieldsets>` and
  :attr:`InlineModelAdmin.fieldsets <django.contrib.admin.InlineModelAdmin>`,
  when the fieldset has a name and use the ``collapse`` class, now includes
  ``<details>`` and ``<summary>`` elements.

* The JavaScript file ``collapse.js`` is removed since it is no longer needed
  in the Django admin site.

* :meth:`.SimpleTestCase.assertURLEqual` and
  :meth:`~django.test.SimpleTestCase.assertInHTML` now add ``": "`` to the
  ``msg_prefix``. This is consistent with the behavior of other assertions.

* ``django.utils.text.Truncator`` used by :tfilter:`truncatechars_html` and
  :tfilter:`truncatewords_html` template filters now uses
  :py:class:`html.parser.HTMLParser` subclasses. This results in a more robust
  and faster operation, but there may be small differences in the output.

* The undocumented ``django.urls.converters.get_converter()`` function is
  removed.

* The minimum supported version of SQLite is increased from 3.27.0 to 3.31.0.

* :class:`~django.db.models.FileField` now raises a
  :class:`~django.core.exceptions.FieldError` when saving a file without a
  ``name``.

* ``ImageField.update_dimension_fields(force=True)`` is no longer called after
  saving the image to storage. If your storage backend resizes images, the
  ``width_field`` and ``height_field`` will not match the width and height of
  the image.

.. _deprecated-features-5.1:

Features deprecated in 5.1
==========================

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

* The ``ModelAdmin.log_deletion()`` and ``LogEntryManager.log_action()``
  methods are deprecated. Subclasses should implement
  ``ModelAdmin.log_deletions()`` and  ``LogEntryManager.log_actions()``
  instead.

* The undocumented ``django.utils.itercompat.is_iterable()`` function and the
  ``django.utils.itercompat`` module are deprecated. Use
  ``isinstance(..., collections.abc.Iterable)`` instead.

* The ``django.contrib.gis.geoip2.GeoIP2.coords()`` method is deprecated. Use
  ``django.contrib.gis.geoip2.GeoIP2.lon_lat()`` instead.

* The ``django.contrib.gis.geoip2.GeoIP2.open()`` method is deprecated. Use the
  :class:`~django.contrib.gis.geoip2.GeoIP2` constructor instead.

* Passing positional arguments to :meth:`.Model.save` and :meth:`.Model.asave`
  is deprecated in favor of keyword-only arguments.

* Setting ``django.contrib.gis.gdal.OGRGeometry.coord_dim`` is deprecated. Use
  :meth:`~django.contrib.gis.gdal.OGRGeometry.set_3d` instead.

* Overriding existing converters with ``django.urls.register_converter()`` is
  deprecated.

* The ``check`` keyword argument of ``CheckConstraint`` is deprecated in favor
  of ``condition``.

* The undocumented ``OS_OPEN_FLAGS`` property of
  :class:`~django.core.files.storage.FileSystemStorage` is deprecated. To allow
  overwriting files in storage, set the new
  :attr:`~django.core.files.storage.FileSystemStorage.allow_overwrite` option
  to ``True`` instead.

* The ``get_cache_name()`` method of ``FieldCacheMixin`` is deprecated in favor
  of the ``cache_name`` cached property.

Features removed in 5.1
=======================

These features have reached the end of their deprecation cycle and are removed
in Django 5.1.

See :ref:`deprecated-features-4.2` for details on these changes, including how
to remove usage of these features.

* The ``BaseUserManager.make_random_password()`` method is removed.

* The model's ``Meta.index_together`` option is removed.

* The ``length_is`` template filter is removed.

* The ``django.contrib.auth.hashers.SHA1PasswordHasher``,
  ``django.contrib.auth.hashers.UnsaltedSHA1PasswordHasher``, and
  ``django.contrib.auth.hashers.UnsaltedMD5PasswordHasher`` are removed.

* The model ``django.contrib.postgres.fields.CICharField``,
  ``django.contrib.postgres.fields.CIEmailField``, and
  ``django.contrib.postgres.fields.CITextField`` are removed, except for
  support in historical migrations.

* The ``django.contrib.postgres.fields.CIText`` mixin is removed.

* The ``map_width`` and ``map_height`` attributes of ``BaseGeometryWidget`` are
  removed.

* The ``SimpleTestCase.assertFormsetError()`` method is removed.

* The ``TransactionTestCase.assertQuerysetEqual()`` method is removed.

* Support for passing encoded JSON string literals to ``JSONField`` and
  associated lookups and expressions is removed.

* Support for passing positional arguments to ``Signer`` and
  ``TimestampSigner`` is removed.

* The ``DEFAULT_FILE_STORAGE`` and ``STATICFILES_STORAGE`` settings is removed.

* The ``django.core.files.storage.get_storage_class()`` function is removed.
