December 7, 2021
Welcome to Django 4.0!
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 3.2 or earlier. We’ve begun the deprecation process for some features.
See the How to upgrade Django to a newer version guide if you’re updating an existing project.
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.
The Django 3.2.x series is the last to support Python 3.6 and 3.7.
zoneinfo default timezone implementation¶The Python standard library’s zoneinfo is now the default timezone
implementation in Django.
This is the next step in the migration from using pytz to using
zoneinfo. Django 3.2 allowed the use of non-pytz time zones. Django
4.0 makes zoneinfo the default implementation. Support for pytz is now
deprecated and will be removed in Django 5.0.
zoneinfo is part of the Python standard library from Python 3.9. The
backports.zoneinfo package is automatically installed alongside Django if
you are using Python 3.8.
The move to zoneinfo should be largely transparent. Selection of the
current timezone, conversion of datetime instances to the current timezone in
forms and templates, as well as operations on aware datetimes in UTC are
unaffected.
However, if you are working with non-UTC time zones, and using the pytz
normalize() and localize() APIs, possibly with the TIME_ZONE setting, you will need to audit your code, since pytz
and zoneinfo are not entirely equivalent.
To give time for such an audit, the transitional USE_DEPRECATED_PYTZ
setting allows continued use of pytz during the 4.x release cycle. This
setting will be removed in Django 5.0.
In addition, a pytz_deprecation_shim package, created by the zoneinfo
author, can be used to assist with the migration from pytz. This package
provides shims to help you safely remove pytz, and has a detailed
migration guide showing how to move to the new zoneinfo APIs.
Using pytz_deprecation_shim and the USE_DEPRECATED_PYTZ
transitional setting is recommended if you need a gradual update path.
The new *expressions
positional argument of
UniqueConstraint() enables
creating functional unique constraints on expressions and database functions.
For example:
from django.db import models
from django.db.models import UniqueConstraint
from django.db.models.functions import Lower
class MyModel(models.Model):
first_name = models.CharField(max_length=255)
last_name = models.CharField(max_length=255)
class Meta:
constraints = [
UniqueConstraint(
Lower("first_name"),
Lower("last_name").desc(),
name="first_last_name_unique",
),
]
Functional unique constraints are added to models using the
Meta.constraints option.
scrypt password hasher¶The new scrypt password hasher is more secure and recommended over PBKDF2. However, it’s not the default as it requires OpenSSL 1.1+ and more memory.
The new django.core.cache.backends.redis.RedisCache cache backend provides
built-in support for caching with Redis. redis-py 3.0.0 or
higher is required. For more details, see the documentation on caching
with Redis in Django.
Forms, Formsets,
and ErrorList are now rendered using the template engine
to enhance customization. See the new render(),
get_context(), and
template_name for Form and
formset rendering for Formset.
django.contrib.admin¶The admin/base.html template now has a new block header which
contains the admin site header.
The new ModelAdmin.get_formset_kwargs() method allows customizing the
keyword arguments passed to the constructor of a formset.
The navigation sidebar now has a quick filter toolbar.
The new context variable model which contains the model class for each
model is added to the AdminSite.each_context() method.
The new ModelAdmin.search_help_text attribute allows specifying a
descriptive text for the search box.
The InlineModelAdmin.verbose_name_plural attribute now fallbacks to
the InlineModelAdmin.verbose_name + 's'.
jQuery is upgraded from version 3.5.1 to 3.6.0.
django.contrib.admindocs¶The admindocs now allows esoteric setups where ROOT_URLCONF is not
a string.
The model section of the admindocs now shows cached properties.
django.contrib.auth¶The default iteration count for the PBKDF2 password hasher is increased from 260,000 to 320,000.
The new
LoginView.next_page
attribute and
get_default_redirect_url() method
allow customizing the redirect after login.
django.contrib.gis¶Added support for SpatiaLite 5.
GDALRaster now allows creating rasters in
any GDAL virtual filesystem.
The new GISModelAdmin class allows
customizing the widget used for GeometryField. This is encouraged instead
of deprecated GeoModelAdmin and OSMGeoAdmin.
django.contrib.postgres¶The PostgreSQL backend now supports connecting by a service name. See PostgreSQL connection settings for more details.
The new AddConstraintNotValid
operation allows creating check constraints on PostgreSQL without verifying
that all existing rows satisfy the new constraint.
The new ValidateConstraint
operation allows validating check constraints which were created using
AddConstraintNotValid on
PostgreSQL.
The new
ArraySubquery()
expression allows using subqueries to construct lists of values on
PostgreSQL.
The new trigram_word_similar lookup, and the
TrigramWordDistance() and
TrigramWordSimilarity() expressions allow
using trigram word similarity.
django.contrib.staticfiles¶ManifestStaticFilesStorage now
replaces paths to JavaScript source map references with their hashed
counterparts.
The new manifest_storage argument of
ManifestFilesMixin and
ManifestStaticFilesStorage
allows customizing the manifest file storage.
The new async API for django.core.cache.backends.base.BaseCache begins
the process of making cache backends async-compatible. The new async methods
all have a prefixed names, e.g. aadd(), aget(), aset(),
aget_or_set(), or adelete_many().
Going forward, the a prefix will be used for async variants of methods
generally.
CSRF protection now consults the Origin header, if present. To facilitate
this, some changes to the
CSRF_TRUSTED_ORIGINS setting are required.
ModelChoiceField now includes the provided value in
the params argument of a raised
ValidationError for the invalid_choice
error message. This allows custom error messages to use the %(value)s
placeholder.
BaseFormSet now renders non-form errors with
an additional class of nonform to help distinguish them from
form-specific errors.
BaseFormSet now allows customizing the widget
used when deleting forms via
can_delete by setting the
deletion_widget attribute or
overriding get_deletion_widget()
method.
Added support and translations for the Malay language.
DeleteView now uses
FormMixin, allowing you to provide a
Form subclass, with a checkbox for example, to confirm
deletion. In addition, this allows DeleteView to function with
django.contrib.messages.views.SuccessMessageMixin.
In accordance with FormMixin, object deletion for POST requests is
handled in form_valid(). Custom delete logic in delete() handlers
should be moved to form_valid(), or a shared helper method, as needed.
The alias of the database used in an SQL call is now passed as extra context along with each message to the django.db.backends logger.
The runserver management command now supports the
--skip-checks option.
On PostgreSQL, dbshell now supports specifying a password file.
The shell command now respects sys.__interactivehook__
at startup. This allows loading shell history between interactive sessions.
As a consequence, readline is no longer loaded if running in isolated
mode.
The new BaseCommand.suppressed_base_arguments attribute
allows suppressing unsupported default command options in the help output.
The new startapp --exclude and startproject --exclude
options allow excluding directories from the template.
New QuerySet.contains(obj) method returns
whether the queryset contains the given object. This tries to perform the
query in the simplest and fastest way possible.
The new precision argument of the
Round() database function allows
specifying the number of decimal places after rounding.
QuerySet.bulk_create() now sets the primary key on objects when using
SQLite 3.35+.
DurationField now supports multiplying and
dividing by scalar values on SQLite.
QuerySet.bulk_update() now returns the number of objects updated.
The new Expression.empty_result_set_value attribute allows
specifying a value to return when the function is used over an empty result
set.
The skip_locked argument of QuerySet.select_for_update() is now
allowed on MariaDB 10.6+.
Lookup expressions may now be used in QuerySet
annotations, aggregations, and directly in filters.
The new default argument for built-in aggregates
allows specifying a value to be returned when the queryset (or grouping)
contains no entries, rather than None.
The SecurityMiddleware now adds the
Cross-Origin Opener Policy header with a
value of 'same-origin' to prevent cross-origin popups from sharing the
same browsing context. You can prevent this header from being added by
setting the SECURE_CROSS_ORIGIN_OPENER_POLICY setting to None.
The new stdout argument for pre_migrate()
and post_migrate() signals allows redirecting
output to a stream-like object. It should be preferred over
sys.stdout and print() when emitting verbose output in
order to allow proper capture when testing.
floatformat template filter now allows using the u suffix to
force disabling localization.
The new serialized_aliases argument of
django.test.utils.setup_databases() determines which
DATABASES aliases test databases should have their state
serialized to allow usage of the
serialized_rollback feature.
Django test runner now supports a --buffer option
with parallel tests.
The new logger argument to DiscoverRunner
allows a Python logger to be used for logging.
The new DiscoverRunner.log() method provides a way to log messages
that uses the DiscoverRunner.logger, or prints to the console if not set.
Django test runner now supports a --shuffle option
to execute tests in a random order.
The test --parallel option now supports the value auto to run
one test process for each processor core.
TestCase.captureOnCommitCallbacks() now captures new callbacks added
while executing transaction.on_commit() callbacks.
This section describes changes that may be needed in third-party database backends.
DatabaseOperations.year_lookup_bounds_for_date_field() and
year_lookup_bounds_for_datetime_field() methods now take the optional
iso_year argument in order to support bounds for ISO-8601 week-numbering
years.
The second argument of DatabaseSchemaEditor._unique_sql() and
_create_unique_sql() methods is now fields instead of columns.
django.contrib.gis¶Support for PostGIS 2.3 is removed.
Support for GDAL 2.0 and GEOS 3.5 is removed.
Upstream support for PostgreSQL 9.6 ends in November 2021. Django 4.0 supports PostgreSQL 10 and higher.
Also, the minimum supported version of psycopg2 is increased from 2.5.4 to
2.8.4, as psycopg2 2.8.4 is the first release to support Python 3.8.
Upstream support for Oracle 12.2 ends in March 2022 and for Oracle 18c it ends in June 2021. Django 3.2 will be supported until April 2024. Django 4.0 officially supports Oracle 19c.
CSRF_TRUSTED_ORIGINS changes¶Values in the CSRF_TRUSTED_ORIGINS setting must include the scheme
(e.g. 'http://' or 'https://') instead of only the hostname.
Also, values that started with a dot, must now also include an asterisk before
the dot. For example, change '.example.com' to 'https://*.example.com'.
A system check detects any required changes.
As CSRF protection now consults the Origin header, you may need to set
CSRF_TRUSTED_ORIGINS, particularly if you allow requests from
subdomains by setting CSRF_COOKIE_DOMAIN (or
SESSION_COOKIE_DOMAIN if CSRF_USE_SESSIONS is enabled) to
a value starting with a dot.
SecurityMiddleware no longer sets the X-XSS-Protection header¶The SecurityMiddleware no longer sets the
X-XSS-Protection header if the SECURE_BROWSER_XSS_FILTER setting is
True. The setting is removed.
Most modern browsers don’t honor the X-XSS-Protection HTTP header. You can
use Content-Security-Policy without allowing 'unsafe-inline' scripts
instead.
If you want to support legacy browsers and set the header, use this line in a custom middleware:
response.headers.setdefault("X-XSS-Protection", "1; mode=block")
The migrations autodetector now uses model states instead of model classes.
Also, migration operations for ForeignKey and ManyToManyField fields no
longer specify attributes which were not passed to the fields during
initialization.
As a side-effect, running makemigrations might generate no-op
AlterField operations for ManyToManyField and ForeignKey fields in
some cases.
DeleteView changes¶DeleteView now uses
FormMixin to handle POST requests. As a
consequence, any custom deletion logic in delete() handlers should be
moved to form_valid(), or a shared helper method, if required.
Django 4.0 inadvertently changed the table and column naming scheme on Oracle.
This causes errors for models and fields with names longer than 30 characters.
Unfortunately, renaming some Oracle tables and columns is required. Use the
upgrade script in 33789 to generate RENAME
statements to change naming scheme.
Support for cx_Oracle < 7.0 is removed.
To allow serving a Django site on a subpath without changing the value of
STATIC_URL, the leading slash is removed from that setting (now
'static/') in the default startproject template.
The AdminSite method for the admin index
view is no longer decorated with never_cache when accessed directly,
rather than via the recommended AdminSite.urls property, or
AdminSite.get_urls() method.
Unsupported operations on a sliced queryset now raise TypeError instead
of AssertionError.
The undocumented django.test.runner.reorder_suite() function is renamed
to reorder_tests(). It now accepts an iterable of tests rather than a
test suite, and returns an iterator of tests.
Calling FileSystemStorage.delete() with an empty name now raises
ValueError instead of AssertionError.
Calling EmailMultiAlternatives.attach_alternative() or
EmailMessage.attach() with an invalid content or mimetype
arguments now raise ValueError instead of AssertionError.
assertHTMLEqual() no longer considers a
non-boolean attribute without a value equal to an attribute with the same
name and value.
Tests that fail to load, for example due to syntax errors, now always match
when using test --tag.
The undocumented django.contrib.admin.utils.lookup_needs_distinct()
function is renamed to lookup_spawns_duplicates().
The undocumented HttpRequest.get_raw_uri() method is removed. The
HttpRequest.build_absolute_uri() method may be a suitable alternative.
The object argument of undocumented ModelAdmin.log_addition(),
log_change(), and log_deletion() methods is renamed to obj.
RssFeed,
Atom1Feed, and their subclasses now emit
elements with no content as self-closing tags.
NodeList.render() no longer casts the output of render() method for
individual nodes to a string. Node.render() should always return a string
as documented.
The where_class property of django.db.models.sql.query.Query and the
where_class argument to the private get_extra_restriction() method of
ForeignObject and ForeignObjectRel are removed. If needed, initialize
django.db.models.sql.where.WhereNode instead.
The filter_clause argument of the undocumented Query.add_filter()
method is replaced by two positional arguments filter_lhs and
filter_rhs.
CsrfViewMiddleware now uses
request.META['CSRF_COOKIE_NEEDS_UPDATE'] in place of
request.META['CSRF_COOKIE_USED'], request.csrf_cookie_needs_reset,
and response.csrf_cookie_set to track whether the CSRF cookie should be
sent. This is an undocumented, private API.
The undocumented TRANSLATOR_COMMENT_MARK constant is moved from
django.template.base to django.utils.translation.template.
The real_apps argument of the undocumented
django.db.migrations.state.ProjectState.__init__() method must now be a
set if provided.
RadioSelect and
CheckboxSelectMultiple widgets are now rendered in
<div> tags so they are announced more concisely by screen readers. If you
need the previous behavior, override the widget template with the appropriate template from
Django 3.2.
The floatformat template filter no longer depends on the
USE_L10N setting and always returns localized output. Use the u
suffix to disable localization.
The default value of the USE_L10N setting is changed to True. See the
Localization section above for more details.
As part of the move to zoneinfo,
django.utils.timezone.utc is changed to alias
datetime.timezone.utc.
The minimum supported version of asgiref is increased from 3.3.2 to
3.4.1.
pytz time zones¶As part of the move to zoneinfo, use of pytz time
zones is deprecated.
Accordingly, the is_dst arguments to the following are also deprecated:
Support for use of pytz will be removed in Django 5.0.
In order to follow good practice, the default value of the USE_TZ
setting will change from False to True, and time zone support will be
enabled by default, in Django 5.0.
Note that the default settings.py file created by
django-admin startproject includes
USE_TZ = True since Django 1.4.
You can set USE_TZ to False in your project settings before then to
opt-out.
In order to follow good practice, the default value of the USE_L10N setting
is changed from False to True.
Moreover USE_L10N is deprecated as of this release. Starting with Django
5.0, by default, any date or number displayed by Django will be localized.
The {% localize %} tag and the localize/
unlocalize filters will still be honored by Django.
SERIALIZE test setting is deprecated as it can be inferred from the
databases with the
serialized_rollback option enabled.
The undocumented django.utils.baseconv module is deprecated.
The undocumented django.utils.datetime_safe module is deprecated.
The default sitemap protocol for sitemaps built outside the context of a
request will change from 'http' to 'https' in Django 5.0.
The extra_tests argument for DiscoverRunner.build_suite() and
DiscoverRunner.run_tests() is deprecated.
The ArrayAgg,
JSONBAgg, and
StringAgg aggregates will return
None when there are no rows instead of [], [], and ''
respectively in Django 5.0. If you need the previous behavior, explicitly set
default to Value([]), Value('[]'), or Value('').
The django.contrib.gis.admin.GeoModelAdmin and OSMGeoAdmin classes
are deprecated. Use ModelAdmin and
GISModelAdmin instead.
Since form rendering now uses the template engine, the undocumented
BaseForm._html_output() helper method is deprecated.
The ability to return a str from ErrorList and ErrorDict is
deprecated. It is expected these methods return a SafeString.
These features have reached the end of their deprecation cycle and are removed in Django 4.0.
See Features deprecated in 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 Features deprecated in 3.1 for details on these changes, including how to remove usage of these features.
The PASSWORD_RESET_TIMEOUT_DAYS setting is removed.
The 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_response 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.
Dec 25, 2023