docs/releases/4.1.txt
========================
Django 4.1 release notes
========================
*August 3, 2022*
Welcome to Django 4.1!
These release notes cover the :ref:`new features <whats-new-4.1>`, as well as
some :ref:`backwards incompatible changes <backwards-incompatible-4.1>` you'll
want to be aware of when upgrading from Django 4.0 or earlier. We've
:ref:`begun the deprecation process for some features
<deprecated-features-4.1>`.
See the :doc:`/howto/upgrade-version` guide if you're updating an existing
project.
Python compatibility
====================
Django 4.1 supports Python 3.8, 3.9, 3.10, and 3.11 (as of 4.1.3). We
**highly recommend** and only officially support the latest release of each
series.
.. _whats-new-4.1:
What's new in Django 4.1
========================
Asynchronous handlers for class-based views
-------------------------------------------
View subclasses may now define async HTTP method handlers::
import asyncio
from django.http import HttpResponse
from django.views import View
class AsyncView(View):
async def get(self, request, *args, **kwargs):
# Perform view logic using await.
await asyncio.sleep(1)
return HttpResponse("Hello async world!")
See :ref:`async-class-based-views` for more details.
Asynchronous ORM interface
--------------------------
``QuerySet`` now provides an asynchronous interface for all data access
operations. These are named as-per the existing synchronous operations but with
an ``a`` prefix, for example ``acreate()``, ``aget()``, and so on.
The new interface allows you to write asynchronous code without needing to wrap
ORM operations in ``sync_to_async()``::
async for author in Author.objects.filter(name__startswith="A"):
book = await author.books.afirst()
Note that, at this stage, the underlying database operations remain
synchronous, with contributions ongoing to push asynchronous support down into
the SQL compiler, and integrate asynchronous database drivers. The new
asynchronous queryset interface currently encapsulates the necessary
``sync_to_async()`` operations for you, and will allow your code to take
advantage of developments in the ORM's asynchronous support as it evolves.
See :ref:`async-queries` for details and limitations.
Validation of Constraints
-------------------------
:class:`Check <django.db.models.CheckConstraint>`,
:class:`unique <django.db.models.UniqueConstraint>`, and :class:`exclusion
<django.contrib.postgres.constraints.ExclusionConstraint>` constraints defined
in the :attr:`Meta.constraints <django.db.models.Options.constraints>` option
are now checked during :ref:`model validation <validating-objects>`.
Form rendering accessibility
----------------------------
In order to aid users with screen readers, and other assistive technology, new
``<div>`` based form templates are available from this release. These provide
more accessible navigation than the older templates, and are able to correctly
group related controls, such as radio-lists, into fieldsets.
The new templates are recommended, and will become the default form rendering
style when outputting a form, like ``{{ form }}`` in a template, from Django
5.0.
In order to ease adopting the new output style, the default form and formset
templates are now configurable at the project level via the
:setting:`FORM_RENDERER` setting.
See :ref:`the Forms section (below)<forms-4.1>` for full details.
.. _csrf-cookie-masked-usage:
``CSRF_COOKIE_MASKED`` setting
------------------------------
The new ``CSRF_COOKIE_MASKED`` transitional setting allows specifying whether
to mask the CSRF cookie.
:class:`~django.middleware.csrf.CsrfViewMiddleware` no longer masks the CSRF
cookie like it does the CSRF token in the DOM. If you are upgrading multiple
instances of the same project to Django 4.1, you should set
``CSRF_COOKIE_MASKED`` to ``True`` during the transition, in order to allow
compatibility with the older versions of Django. Once the transition to 4.1 is
complete you can stop overriding ``CSRF_COOKIE_MASKED``.
This setting is deprecated as of this release and will be removed in Django
5.0.
Minor features
--------------
:mod:`django.contrib.admin`
~~~~~~~~~~~~~~~~~~~~~~~~~~~
* The admin :ref:`dark mode CSS variables <admin-theming>` are now applied in a
separate stylesheet and template block.
* :ref:`modeladmin-list-filters` providing custom ``FieldListFilter``
subclasses can now control the query string value separator when filtering
for multiple values using the ``__in`` lookup.
* The admin :meth:`history view <django.contrib.admin.ModelAdmin.history_view>`
is now paginated.
* Related widget wrappers now have a link to object's change form.
* The :meth:`.AdminSite.get_app_list` method now allows changing the order of
apps and models on the admin index page.
:mod:`django.contrib.auth`
~~~~~~~~~~~~~~~~~~~~~~~~~~
* The default iteration count for the PBKDF2 password hasher is increased from
320,000 to 390,000.
* The :meth:`.RemoteUserBackend.configure_user` method now allows synchronizing
user attributes with attributes in a remote system such as an LDAP directory.
:mod:`django.contrib.gis`
~~~~~~~~~~~~~~~~~~~~~~~~~
* The new :meth:`.GEOSGeometry.make_valid()` method allows converting invalid
geometries to valid ones.
* The new ``clone`` argument for :meth:`.GEOSGeometry.normalize` allows
creating a normalized clone of the geometry.
:mod:`django.contrib.postgres`
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
* The new :class:`BitXor() <django.contrib.postgres.aggregates.BitXor>`
aggregate function returns an ``int`` of the bitwise ``XOR`` of all non-null
input values.
* :class:`~django.contrib.postgres.indexes.SpGistIndex` now supports covering
indexes on PostgreSQL 14+.
* :class:`~django.contrib.postgres.constraints.ExclusionConstraint` now
supports covering exclusion constraints using SP-GiST indexes on PostgreSQL
14+.
* The new ``default_bounds`` attribute of :attr:`DateTimeRangeField
<django.contrib.postgres.fields.DateTimeRangeField.default_bounds>` and
:attr:`DecimalRangeField
<django.contrib.postgres.fields.DecimalRangeField.default_bounds>` allows
specifying bounds for list and tuple inputs.
* :class:`~django.contrib.postgres.constraints.ExclusionConstraint` now allows
specifying operator classes with the
:class:`OpClass() <django.contrib.postgres.indexes.OpClass>` expression.
:mod:`django.contrib.sitemaps`
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
* The default sitemap index template ``<sitemapindex>`` now includes the
``<lastmod>`` timestamp where available, through the new
:meth:`~django.contrib.sitemaps.Sitemap.get_latest_lastmod` method. Custom
sitemap index templates should be updated for the adjusted :ref:`context
variables <sitemap-index-context-variables>`.
:mod:`django.contrib.staticfiles`
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
* :class:`~django.contrib.staticfiles.storage.ManifestStaticFilesStorage` now
replaces paths to CSS source map references with their hashed counterparts.
Database backends
~~~~~~~~~~~~~~~~~
* Third-party database backends can now specify the minimum required version of
the database using the ``DatabaseFeatures.minimum_database_version``
attribute which is a tuple (e.g. ``(10, 0)`` means "10.0"). If a minimum
version is specified, backends must also implement
``DatabaseWrapper.get_database_version()``, which returns a tuple of the
current database version. The backend's
``DatabaseWrapper.init_connection_state()`` method must call ``super()`` in
order for the check to run.
.. _forms-4.1:
Forms
~~~~~
* The default template used to render forms when cast to a string, e.g. in
templates as ``{{ form }}``, is now configurable at the project-level by
setting :attr:`~django.forms.renderers.BaseRenderer.form_template_name` on
the class provided for :setting:`FORM_RENDERER`.
:attr:`.Form.template_name` is now a property deferring to the renderer, but
may be overridden with a string value to specify the template name per-form
class.
Similarly, the default template used to render formsets can be specified via
the matching
:attr:`~django.forms.renderers.BaseRenderer.formset_template_name` renderer
attribute.
* The new ``div.html`` form template, referencing
:attr:`.Form.template_name_div` attribute, and matching :meth:`.Form.as_div`
method, render forms using HTML ``<div>`` elements.
This new output style is recommended over the existing
:meth:`~.Form.as_table`, :meth:`~.Form.as_p` and :meth:`~.Form.as_ul` styles,
as the template implements ``<fieldset>`` and ``<legend>`` to group related
inputs and is easier for screen reader users to navigate.
The div-based output will become the default rendering style from Django 5.0.
* In order to smooth adoption of the new ``<div>`` output style, two
transitional form renderer classes are available:
``django.forms.renderers.DjangoDivFormRenderer`` and
``django.forms.renderers.Jinja2DivFormRenderer``, for the Django and Jinja2
template backends respectively.
You can apply one of these via the :setting:`FORM_RENDERER` setting. For
example::
FORM_RENDERER = "django.forms.renderers.DjangoDivFormRenderer"
Once the ``<div>`` output style is the default, from Django 5.0, these
transitional renderers will be deprecated, for removal in Django 6.0. The
``FORM_RENDERER`` declaration can be removed at that time.
* If the new ``<div>`` output style is not appropriate for your project, you should
define a renderer subclass specifying
:attr:`~django.forms.renderers.BaseRenderer.form_template_name` and
:attr:`~django.forms.renderers.BaseRenderer.formset_template_name` for your
required style, and set :setting:`FORM_RENDERER` accordingly.
For example, for the ``<p>`` output style used by :meth:`~.Form.as_p`, you
would define a form renderer setting ``form_template_name`` to
``"django/forms/p.html"`` and ``formset_template_name`` to
``"django/forms/formsets/p.html"``.
* The new :meth:`~django.forms.BoundField.legend_tag` allows rendering field
labels in ``<legend>`` tags via the new ``tag`` argument of
:meth:`~django.forms.BoundField.label_tag`.
* The new ``edit_only`` argument for :func:`.modelformset_factory` and
:func:`.inlineformset_factory` allows preventing new objects creation.
* The ``js`` and ``css`` class attributes of :doc:`Media </topics/forms/media>`
now allow using hashable objects, not only path strings, as long as those
objects implement the ``__html__()`` method (typically when decorated with
the :func:`~django.utils.html.html_safe` decorator).
* The new :attr:`.BoundField.use_fieldset` and :attr:`.Widget.use_fieldset`
attributes help to identify widgets where its inputs should be grouped in a
``<fieldset>`` with a ``<legend>``.
* The :ref:`formsets-error-messages` argument for
:class:`~django.forms.formsets.BaseFormSet` now allows customizing
error messages for invalid number of forms by passing ``'too_few_forms'``
and ``'too_many_forms'`` keys.
* :class:`~django.forms.IntegerField`, :class:`~django.forms.FloatField`, and
:class:`~django.forms.DecimalField` now optionally accept a ``step_size``
argument. This is used to set the ``step`` HTML attribute, and is validated
on form submission.
Internationalization
~~~~~~~~~~~~~~~~~~~~
* The :func:`~django.conf.urls.i18n.i18n_patterns` function now supports
languages with both scripts and regions.
Management Commands
~~~~~~~~~~~~~~~~~~~
* :option:`makemigrations --no-input` now logs default answers and reasons why
migrations cannot be created.
* The new :option:`makemigrations --scriptable` option diverts log output and
input prompts to ``stderr``, writing only paths of generated migration files
to ``stdout``.
* The new :option:`migrate --prune` option allows deleting nonexistent
migrations from the ``django_migrations`` table.
* Python files created by :djadmin:`startproject`, :djadmin:`startapp`,
:djadmin:`optimizemigration`, :djadmin:`makemigrations`, and
:djadmin:`squashmigrations` are now formatted using the ``black`` command if
it is present on your ``PATH``.
* The new :djadmin:`optimizemigration` command allows optimizing operations for
a migration.
Migrations
~~~~~~~~~~
* The new :class:`~django.db.migrations.operations.RenameIndex` operation
allows renaming indexes defined in the
:attr:`Meta.indexes <django.db.models.Options.indexes>` or
``index_together`` options.
* The migrations autodetector now generates
:class:`~django.db.migrations.operations.RenameIndex` operations instead of
``RemoveIndex`` and ``AddIndex``, when renaming indexes defined in the
:attr:`Meta.indexes <django.db.models.Options.indexes>`.
* The migrations autodetector now generates
:class:`~django.db.migrations.operations.RenameIndex` operations instead of
``AlterIndexTogether`` and ``AddIndex``, when moving indexes defined in the
``Meta.index_together`` to the
:attr:`Meta.indexes <django.db.models.Options.indexes>`.
Models
~~~~~~
* The ``order_by`` argument of the
:class:`~django.db.models.expressions.Window` expression now accepts string
references to fields and transforms.
* The new :setting:`CONN_HEALTH_CHECKS` setting allows enabling health checks
for :ref:`persistent database connections <persistent-database-connections>`
in order to reduce the number of failed requests, e.g. after database server
restart.
* :meth:`.QuerySet.bulk_create` now supports updating fields when a row
insertion fails uniqueness constraints. This is supported on MariaDB, MySQL,
PostgreSQL, and SQLite 3.24+.
* :meth:`.QuerySet.iterator` now supports prefetching related objects as long
as the ``chunk_size`` argument is provided. In older versions, no prefetching
was done.
* :class:`~django.db.models.Q` objects and querysets can now be combined using
``^`` as the exclusive or (``XOR``) operator. ``XOR`` is natively supported
on MariaDB and MySQL. For databases that do not support ``XOR``, the query
will be converted to an equivalent using ``AND``, ``OR``, and ``NOT``.
* The new :ref:`Field.non_db_attrs <custom-field-non_db_attrs>` attribute
allows customizing attributes of fields that don't affect a column
definition.
* On PostgreSQL, ``AutoField``, ``BigAutoField``, and ``SmallAutoField`` are
now created as identity columns rather than serial columns with sequences.
Requests and Responses
~~~~~~~~~~~~~~~~~~~~~~
* :meth:`.HttpResponse.set_cookie` now supports :class:`~datetime.timedelta`
objects for the ``max_age`` argument.
Security
~~~~~~~~
* The new :setting:`SECRET_KEY_FALLBACKS` setting allows providing a list of
values for secret key rotation.
* The :setting:`SECURE_PROXY_SSL_HEADER` setting now supports a comma-separated
list of protocols in the header value.
Signals
~~~~~~~
* The :data:`~django.db.models.signals.pre_delete` and
:data:`~django.db.models.signals.post_delete` signals now dispatch the
``origin`` of the deletion.
.. _templates-4.1:
Templates
~~~~~~~~~
* The HTML ``<script>`` element ``id`` attribute is no longer required when
wrapping the :tfilter:`json_script` template filter.
* The :class:`cached template loader <django.template.loaders.cached.Loader>`
is now enabled in development, when :setting:`DEBUG` is ``True``, and
:setting:`OPTIONS['loaders'] <TEMPLATES-OPTIONS>` isn't specified. You may
specify ``OPTIONS['loaders']`` to override this, if necessary.
Tests
~~~~~
* The :class:`.DiscoverRunner` now supports running tests in parallel on
macOS, Windows, and any other systems where the default
:mod:`multiprocessing` start method is ``spawn``.
* A nested atomic block marked as durable in :class:`django.test.TestCase` now
raises a ``RuntimeError``, the same as outside of tests.
* :meth:`.SimpleTestCase.assertFormError` and
:meth:`assertFormsetError() <django.test.SimpleTestCase.assertFormSetError>`
now support passing a form/formset object directly.
URLs
~~~~
* The new :attr:`.ResolverMatch.captured_kwargs` attribute stores the captured
keyword arguments, as parsed from the URL.
* The new :attr:`.ResolverMatch.extra_kwargs` attribute stores the additional
keyword arguments passed to the view function.
Utilities
~~~~~~~~~
* ``SimpleLazyObject`` now supports addition operations.
* :func:`~django.utils.safestring.mark_safe` now preserves lazy objects.
Validators
~~~~~~~~~~
* The new :class:`~django.core.validators.StepValueValidator` checks if a value
is an integral multiple of a given step size. This new validator is used for
the new ``step_size`` argument added to form fields representing numeric
values.
.. _backwards-incompatible-4.1:
Backwards incompatible changes in 4.1
=====================================
Database backend API
--------------------
This section describes changes that may be needed in third-party database
backends.
* ``BaseDatabaseFeatures.has_case_insensitive_like`` is changed from ``True``
to ``False`` to reflect the behavior of most databases.
* ``DatabaseIntrospection.get_key_columns()`` is removed. Use
``DatabaseIntrospection.get_relations()`` instead.
* ``DatabaseOperations.ignore_conflicts_suffix_sql()`` method is replaced by
``DatabaseOperations.on_conflict_suffix_sql()`` that accepts the ``fields``,
``on_conflict``, ``update_fields``, and ``unique_fields`` arguments.
* The ``ignore_conflicts`` argument of the
``DatabaseOperations.insert_statement()`` method is replaced by
``on_conflict`` that accepts ``django.db.models.constants.OnConflict``.
* ``DatabaseOperations._convert_field_to_tz()`` is replaced by
``DatabaseOperations._convert_sql_to_tz()`` that accepts the ``sql``,
``params``, and ``tzname`` arguments.
* Several date and time methods on ``DatabaseOperations`` now take ``sql`` and
``params`` arguments instead of ``field_name`` and return 2-tuple containing
some SQL and the parameters to be interpolated into that SQL. The changed
methods have these new signatures:
* ``DatabaseOperations.date_extract_sql(lookup_type, sql, params)``
* ``DatabaseOperations.datetime_extract_sql(lookup_type, sql, params, tzname)``
* ``DatabaseOperations.time_extract_sql(lookup_type, sql, params)``
* ``DatabaseOperations.date_trunc_sql(lookup_type, sql, params, tzname=None)``
* ``DatabaseOperations.datetime_trunc_sql(self, lookup_type, sql, params, tzname)``
* ``DatabaseOperations.time_trunc_sql(lookup_type, sql, params, tzname=None)``
* ``DatabaseOperations.datetime_cast_date_sql(sql, params, tzname)``
* ``DatabaseOperations.datetime_cast_time_sql(sql, params, tzname)``
:mod:`django.contrib.gis`
-------------------------
* Support for GDAL 2.1 is removed.
* Support for PostGIS 2.4 is removed.
Dropped support for PostgreSQL 10
---------------------------------
Upstream support for PostgreSQL 10 ends in November 2022. Django 4.1 supports
PostgreSQL 11 and higher.
Dropped support for MariaDB 10.2
--------------------------------
Upstream support for MariaDB 10.2 ends in May 2022. Django 4.1 supports MariaDB
10.3 and higher.
Admin changelist searches spanning multi-valued relationships changes
---------------------------------------------------------------------
Admin changelist searches using multiple search terms are now applied in a
single call to ``filter()``, rather than in sequential ``filter()`` calls.
For multi-valued relationships, this means that rows from the related model
must match all terms rather than any term. For example, if ``search_fields``
is set to ``['child__name', 'child__age']``, and a user searches for
``'Jamal 17'``, parent rows will be returned only if there is a relationship to
some 17-year-old child named Jamal, rather than also returning parents who
merely have a younger or older child named Jamal in addition to some other
17-year-old.
See the :ref:`spanning-multi-valued-relationships` topic for more discussion of
this difference. In Django 4.0 and earlier,
:meth:`~django.contrib.admin.ModelAdmin.get_search_results` followed the
second example query, but this undocumented behavior led to queries with
excessive joins.
Reverse foreign key changes for unsaved model instances
-------------------------------------------------------
In order to unify the behavior with many-to-many relations for unsaved model
instances, a reverse foreign key now raises ``ValueError`` when calling
:class:`related managers <django.db.models.fields.related.RelatedManager>` for
unsaved objects.
Miscellaneous
-------------
* Related managers for :class:`~django.db.models.ForeignKey`,
:class:`~django.db.models.ManyToManyField`, and
:class:`~django.contrib.contenttypes.fields.GenericRelation` are now cached
on the :class:`~django.db.models.Model` instance to which they belong. *This
change was reverted in Django 4.1.2.*
* :class:`~django.test.runner.DiscoverRunner` now returns a non-zero error code
for unexpected successes from tests marked with
:py:func:`unittest.expectedFailure`.
* :class:`~django.middleware.csrf.CsrfViewMiddleware` no longer masks the CSRF
cookie like it does the CSRF token in the DOM.
* :class:`~django.middleware.csrf.CsrfViewMiddleware` now uses
``request.META['CSRF_COOKIE']`` for storing the unmasked CSRF secret rather
than a masked version. This is an undocumented, private API.
* The :attr:`.ModelAdmin.actions` and
:attr:`~django.contrib.admin.ModelAdmin.inlines` attributes now default to an
empty tuple rather than an empty list to discourage unintended mutation.
* The ``type="text/css"`` attribute is no longer included in ``<link>`` tags
for CSS :doc:`form media </topics/forms/media>`.
* ``formset:added`` and ``formset:removed`` JavaScript events are now pure
JavaScript events and don't depend on jQuery. See
:ref:`admin-javascript-inline-form-events` for more details on the change.
* The ``exc_info`` argument of the undocumented
``django.utils.log.log_response()`` function is replaced by ``exception``.
* The ``size`` argument of the undocumented
``django.views.static.was_modified_since()`` function is removed.
* The admin log out UI now uses ``POST`` requests.
* The undocumented ``InlineAdminFormSet.non_form_errors`` property is replaced
by the ``non_form_errors()`` method. This is consistent with ``BaseFormSet``.
* As per :ref:`above<templates-4.1>`, the cached template loader is now
enabled in development. You may specify ``OPTIONS['loaders']`` to override
this, if necessary.
* The undocumented ``django.contrib.auth.views.SuccessURLAllowedHostsMixin``
mixin is replaced by ``RedirectURLMixin``.
* :class:`~django.db.models.BaseConstraint` subclasses must implement
:meth:`~django.db.models.BaseConstraint.validate` method to allow those
constraints to be used for validation.
* The undocumented ``URLResolver._is_callback()``,
``URLResolver._callback_strs``, and ``URLPattern.lookup_str()`` are
moved to ``django.contrib.admindocs.utils``.
* The :meth:`.Model.full_clean` method now converts an ``exclude`` value to a
``set``. It’s also preferable to pass an ``exclude`` value as a ``set`` to
the :meth:`.Model.clean_fields`, :meth:`.Model.full_clean`,
:meth:`.Model.validate_unique`, and :meth:`.Model.validate_constraints`
methods.
* The minimum supported version of ``asgiref`` is increased from 3.4.1 to
3.5.2.
* Combined expressions no longer use the error-prone behavior of guessing
``output_field`` when argument types match. As a consequence, resolving an
``output_field`` for database functions and combined expressions may now
crash with mixed types. You will need to explicitly set the ``output_field``
in such cases.
* The :djadmin:`makemessages` command no longer changes ``.po`` files when up
to date. In older versions, ``POT-Creation-Date`` was always updated.
.. _deprecated-features-4.1:
Features deprecated in 4.1
==========================
Log out via GET
---------------
Logging out via ``GET`` requests to the :py:class:`built-in logout view
<django.contrib.auth.views.LogoutView>` is deprecated. Use ``POST`` requests
instead.
If you want to retain the user experience of an HTML link, you can use a form
that is styled to appear as a link:
.. code-block:: html
<form id="logout-form" method="post" action="{% url 'admin:logout' %}">
{% csrf_token %}
<button type="submit">{% translate "Log out" %}</button>
</form>
.. code-block:: css
#logout-form {
display: inline;
}
#logout-form button {
background: none;
border: none;
cursor: pointer;
padding: 0;
text-decoration: underline;
}
Miscellaneous
-------------
* The context for sitemap index templates of a flat list of URLs is deprecated.
Custom sitemap index templates should be updated for the adjusted
:ref:`context variables <sitemap-index-context-variables>`, expecting a list
of objects with ``location`` and optional ``lastmod`` attributes.
* ``CSRF_COOKIE_MASKED`` transitional setting is deprecated.
* The ``name`` argument of :func:`django.utils.functional.cached_property` is
deprecated as it's unnecessary as of Python 3.6.
* The ``opclasses`` argument of
``django.contrib.postgres.constraints.ExclusionConstraint`` is deprecated in
favor of using :class:`OpClass() <django.contrib.postgres.indexes.OpClass>`
in :attr:`.ExclusionConstraint.expressions`. To use it, you need to add
``'django.contrib.postgres'`` in your :setting:`INSTALLED_APPS`.
After making this change, :djadmin:`makemigrations` will generate a new
migration with two operations: ``RemoveConstraint`` and ``AddConstraint``.
Since this change has no effect on the database schema,
the :class:`~django.db.migrations.operations.SeparateDatabaseAndState`
operation can be used to only update the migration state without running any
SQL. Move the generated operations into the ``state_operations`` argument of
:class:`~django.db.migrations.operations.SeparateDatabaseAndState`. For
example::
class Migration(migrations.Migration):
...
operations = [
migrations.SeparateDatabaseAndState(
database_operations=[],
state_operations=[
migrations.RemoveConstraint(...),
migrations.AddConstraint(...),
],
),
]
* The undocumented ability to pass ``errors=None`` to
:meth:`.SimpleTestCase.assertFormError` and
:meth:`assertFormsetError() <django.test.SimpleTestCase.assertFormSetError>`
is deprecated. Use ``errors=[]`` instead.
* ``django.contrib.sessions.serializers.PickleSerializer`` is deprecated due to
the risk of remote code execution.
* The usage of ``QuerySet.iterator()`` on a queryset that prefetches related
objects without providing the ``chunk_size`` argument is deprecated. In older
versions, no prefetching was done. Providing a value for ``chunk_size``
signifies that the additional query per chunk needed to prefetch is desired.
* Passing unsaved model instances to related filters is deprecated. In Django
5.0, the exception will be raised.
* ``created=True`` is added to the signature of
:meth:`.RemoteUserBackend.configure_user`. Support for ``RemoteUserBackend``
subclasses that do not accept this argument is deprecated.
* The ``django.utils.timezone.utc`` alias to :attr:`datetime.timezone.utc` is
deprecated. Use :attr:`datetime.timezone.utc` directly.
* Passing a response object and a form/formset name to
``SimpleTestCase.assertFormError()`` and ``assertFormsetError()`` is
deprecated. Use::
assertFormError(response.context["form_name"], ...)
assertFormsetError(response.context["formset_name"], ...)
or pass the form/formset object directly instead.
* The undocumented ``django.contrib.gis.admin.OpenLayersWidget`` is deprecated.
* ``django.contrib.auth.hashers.CryptPasswordHasher`` is deprecated.
* The ability to pass ``nulls_first=False`` or ``nulls_last=False`` to
``Expression.asc()`` and ``Expression.desc()`` methods, and the ``OrderBy``
expression is deprecated. Use ``None`` instead.
* The ``"django/forms/default.html"`` and
``"django/forms/formsets/default.html"`` templates which are a proxy to the
table-based templates are deprecated. Use the specific template instead.
* The undocumented ``LogoutView.get_next_page()`` method is renamed to
``get_success_url()``.
Features removed in 4.1
=======================
These features have reached the end of their deprecation cycle and are removed
in Django 4.1.
See :ref:`deprecated-features-3.2` for details on these changes, including how
to remove usage of these features.
* Support for assigning objects which don't support creating deep copies with
``copy.deepcopy()`` to class attributes in ``TestCase.setUpTestData()`` is
removed.
* Support for using a boolean value in
:attr:`.BaseCommand.requires_system_checks` is removed.
* The ``whitelist`` argument and ``domain_whitelist`` attribute of
``django.core.validators.EmailValidator`` are removed.
* The ``default_app_config`` application configuration variable is removed.
* ``TransactionTestCase.assertQuerysetEqual()`` no longer calls ``repr()`` on a
queryset when compared to string values.
* The ``django.core.cache.backends.memcached.MemcachedCache`` backend is
removed.
* Support for the pre-Django 3.2 format of messages used by
``django.contrib.messages.storage.cookie.CookieStorage`` is removed.