Django 3.1 release notes - UNDER DEVELOPMENT

Expected August 2020

Welcome to Django 3.1!

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 3.0 or earlier. We’ve dropped some features that have reached the end of their deprecation cycle, and we’ve begun the deprecation process for some features.

See the Upgrading Django to a newer version guide if you’re updating an existing project.

Python compatibility

Django 3.1 supports Python 3.6, 3.7, and 3.8. We highly recommend and only officially support the latest release of each series.

What’s new in Django 3.1

Asynchronous views and middleware support

Django now supports a fully asynchronous request path, including:

To get started with async views, you need to declare a view using async def:

async def my_view(request):
    await asyncio.sleep(0.5)
    return HttpResponse('Hello, async world!')

All asynchronous features are supported whether you are running under WSGI or ASGI mode. However, there will be performance penalties using async code in WSGI mode. You can read more about the specifics in Asynchronous support documentation.

You are free to mix async and sync views, middleware, and tests as much as you want. Django will ensure that you always end up with the right execution context. We expect most projects will keep the majority of their views synchronous, and only have a select few running in async mode - but it is entirely your choice.

Django’s ORM, cache layer, and other pieces of code that do long-running network calls do not yet support async access. We expect to add support for them in upcoming releases. Async views are ideal, however, if you are doing a lot of API or HTTP calls inside your view, you can now natively do all those HTTP calls in parallel to considerably speed up your view’s execution.

Asynchronous support should be entirely backwards-compatible and we have tried to ensure that it has no speed regressions for your existing, synchronous code. It should have no noticeable effect on any existing Django projects.

Minor features

django.contrib.admin

  • The new django.contrib.admin.EmptyFieldListFilter for ModelAdmin.list_filter allows filtering on empty values (empty strings and nulls) in the admin changelist view.
  • Filters in the right sidebar of the admin changelist view now contains a link to clear all filters.

django.contrib.auth

  • The default iteration count for the PBKDF2 password hasher is increased from 180,000 to 216,000.
  • Added the PASSWORD_RESET_TIMEOUT setting to define the minimum number of seconds a password reset link is valid for. This is encouraged instead of deprecated PASSWORD_RESET_TIMEOUT_DAYS, which will be removed in Django 4.0.
  • The password reset mechanism now uses the SHA-256 hashing algorithm. Support for tokens that use the old hashing algorithm remains until Django 4.0.

django.contrib.contenttypes

django.contrib.gis

django.contrib.humanize

  • intword template filter now supports negative integers.

django.contrib.postgres

django.contrib.sessions

  • The SESSION_COOKIE_SAMESITE setting now allows 'None' (string) value to explicitly state that the cookie is sent with all same-site and cross-site requests.

Cache

CSRF

  • The CSRF_COOKIE_SAMESITE setting now allows 'None' (string) value to explicitly state that the cookie is sent with all same-site and cross-site requests.

Email

Error Reporting

File Storage

  • FileSystemStorage.save() method now supports pathlib.Path.
  • FileField and ImageField now accept a callable for storage. This allows you to modify the used storage at runtime, selecting different storages for different environments, for example.

File Uploads

  • …

Forms

Generic Views

  • …

Internationalization

  • The LANGUAGE_COOKIE_SAMESITE setting now allows 'None' (string) value to explicitly state that the cookie is sent with all same-site and cross-site requests.
  • Added support and translations for the Algerian Arabic language.

Logging

  • …

Management Commands

  • The new check --database option allows specifying database aliases for running the database system checks. Previously these checks were enabled for all configured DATABASES by passing the database tag to the command.
  • The new migrate --check option makes the command exit with a non-zero status when unapplied migrations are detected.
  • The new returncode argument for CommandError allows customizing the exit status for management commands.
  • The new dbshell -- ARGUMENTS option allows passing extra arguments to the command-line client for the database.

Migrations

  • Migrations are now loaded also from directories without __init__.py files.

Models

  • The new ExtractIsoWeekDay function extracts ISO-8601 week days from DateField and DateTimeField, and the new iso_week_day lookup allows querying by an ISO-8601 day of week.
  • QuerySet.explain() now supports:
    • TREE format on MySQL 8.0.16+,
    • analyze option on MySQL 8.0.18+ and MariaDB.
  • Added PositiveBigIntegerField which acts much like a PositiveIntegerField except that it only allows values under a certain (database-dependent) limit. Values from 0 to 9223372036854775807 are safe in all databases supported by Django.
  • The new RESTRICT option for on_delete argument of ForeignKey and OneToOneField emulates the behavior of the SQL constraint ON DELETE RESTRICT.
  • CheckConstraint.check now supports boolean expressions.
  • The RelatedManager.add(), create(), and set() methods now accept callables as values in the through_defaults argument.
  • The new is_dst parameter of the QuerySet.datetimes() determines the treatment of nonexistent and ambiguous datetimes.
  • The new F expression bitxor() method allows bitwise XOR operation.
  • QuerySet.bulk_create() now sets the primary key on objects when using MariaDB 10.5+.
  • The DatabaseOperations.sql_flush() method now generates more efficient SQL on MySQL by using DELETE instead of TRUNCATE statements for tables which don’t require resetting sequences.
  • SQLite functions are now marked as deterministic on Python 3.8+. This allows using them in check constraints and partial indexes.

Requests and Responses

Security

  • The SECURE_REFERRER_POLICY setting now defaults to 'same-origin'. With this configured, SecurityMiddleware sets the Referrer Policy header to same-origin on all responses that do not already have it. This prevents the Referer header being sent to other origins. If you need the previous behavior, explicitly set SECURE_REFERRER_POLICY to None.

  • The default django.core.signing.Signer algorithm is changed to the SHA-256. Support for signatures made with the old SHA-1 algorithm remains until Django 4.0.

    Also, the new algorithm parameter of the Signer allows customizing the hashing algorithm.

Serialization

  • …

Signals

  • …

Templates

  • The renamed translate and blocktranslate template tags are introduced for internationalization in template code. The older trans and blocktrans template tags aliases continue to work, and will be retained for the foreseeable future.
  • The include template tag now accepts iterables of template names.

Tests

  • SimpleTestCase now implements the debug() method to allow running a test without collecting the result and catching exceptions. This can be used to support running tests under a debugger.
  • The new MIGRATE test database setting allows disabling of migrations during a test database creation.
  • Django test runner now supports a test --buffer option to discard output for passing tests.
  • DiscoverRunner now skips running the system checks on databases not referenced by tests.
  • TransactionTestCase teardown is now faster on MySQL due to flush command improvements. As a side effect the latter doesn’t automatically reset sequences on teardown anymore. Enable TransactionTestCase.reset_sequences if your tests require this feature.

URLs

  • Path converters can now raise ValueError in to_url() to indicate no match when reversing URLs.

Utilities

Validators

  • …

Miscellaneous

  • The SQLite backend now supports pathlib.Path for the NAME setting.
  • The settings.py generated by the startproject command now uses pathlib.Path instead of os.path for building filesystem paths.
  • The TIME_ZONE setting is now allowed on databases that support time zones.

Backwards incompatible changes in 3.1

Database backend API

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

  • DatabaseOperations.fetch_returned_insert_columns() now requires an additional returning_params argument.
  • connection.timezone property is now 'UTC' by default, or the TIME_ZONE when USE_TZ is True on databases that support time zones. Previously, it was None on databases that support time zones.
  • connection._nodb_connection property is changed to the connection._nodb_cursor() method and now returns a context manager that yields a cursor and automatically closes the cursor and connection upon exiting the with statement.
  • DatabaseClient.runshell() now requires an additional parameters argument as a list of extra arguments to pass on to the command-line client.

Dropped support for MariaDB 10.1

Upstream support for MariaDB 10.1 ends in October 2020. Django 3.1 supports MariaDB 10.2 and higher.

contrib.admin browser support

The admin no longer supports the legacy Internet Explorer browser. See the admin FAQ for details on supported browsers.

AbstractUser.first_name max_length increased to 150

A migration for django.contrib.auth.models.User.first_name is included. If you have a custom user model inheriting from AbstractUser, you’ll need to generate and apply a database migration for your user model.

If you want to preserve the 30 character limit for first names, use a custom form:

from django import forms
from django.contrib.auth.forms import UserChangeForm

class MyUserChangeForm(UserChangeForm):
    first_name = forms.CharField(max_length=30, required=False)

If you wish to keep this restriction in the admin when editing users, set UserAdmin.form to use this form:

from django.contrib.auth.admin import UserAdmin
from django.contrib.auth.models import User

class MyUserAdmin(UserAdmin):
    form = MyUserChangeForm

admin.site.unregister(User)
admin.site.register(User, MyUserAdmin)

Miscellaneous

  • The cache keys used by cache and generated by make_template_fragment_key() are different from the keys generated by older versions of Django. After upgrading to Django 3.1, the first request to any previously cached template fragment will be a cache miss.
  • The logic behind the decision to return a redirection fallback or a 204 HTTP response from the set_language() view is now based on the Accept HTTP header instead of the X-Requested-With HTTP header presence.
  • The compatibility imports of django.core.exceptions.EmptyResultSet in django.db.models.query, django.db.models.sql, and django.db.models.sql.datastructures are removed.
  • The compatibility import of django.core.exceptions.FieldDoesNotExist in django.db.models.fields is removed.
  • The compatibility imports of django.forms.utils.pretty_name() and django.forms.boundfield.BoundField in django.forms.forms are removed.
  • The compatibility imports of Context, ContextPopException, and RequestContext in django.template.base are removed.
  • The compatibility import of django.contrib.admin.helpers.ACTION_CHECKBOX_NAME in django.contrib.admin is removed.
  • The STATIC_URL and MEDIA_URL settings set to relative paths are now prefixed by the server-provided value of SCRIPT_NAME (or / if not set). This change should not affect settings set to valid URLs or absolute paths.
  • ConditionalGetMiddleware no longer adds the ETag header to responses with an empty content.
  • django.utils.decorators.classproperty() decorator is made public and moved to django.utils.functional.classproperty().
  • floatformat template filter now outputs (positive) 0 for negative numbers which round to zero.
  • Meta.ordering and Meta.unique_together options on models in django.contrib modules that were formerly tuples are now lists.
  • The admin calendar widget now handles two-digit years according to the Open Group Specification, i.e. values between 69 and 99 are mapped to the previous century, and values between 0 and 68 are mapped to the current century.
  • Date-only formats are removed from the default list for DATETIME_INPUT_FORMATS.
  • The FileInput widget no longer renders with the required HTML attribute when initial data exists.
  • The undocumented django.views.debug.ExceptionReporterFilter class is removed. As per the Custom error reports documentation, classes to be used with DEFAULT_EXCEPTION_REPORTER_FILTER needs to inherit from django.views.debug.SafeExceptionReporterFilter.
  • The cache timeout set by cache_page() decorator now takes precedence over the max-age directive from the Cache-Control header.
  • Providing a non-local remote field in the ForeignKey.to_field argument now raises FieldError.
  • SECURE_REFERRER_POLICY now defaults to 'same-origin'. See the What’s New Security section above for more details.
  • check management command now runs the database system checks only for database aliases specified using check --database option.
  • migrate management command now runs the database system checks only for a database to migrate.
  • The admin CSS classes row1 and row2 are removed in favor of :nth-child(odd) and :nth-child(even) pseudo-classes.
  • The make_password() now requires its argument to be a string or bytes. Other types should be explicitly cast to one of these.
  • The undocumented version parameter to the AsKML function is removed.

Features deprecated in 3.1

Miscellaneous

  • PASSWORD_RESET_TIMEOUT_DAYS setting is deprecated in favor of PASSWORD_RESET_TIMEOUT.

  • The undocumented usage of the isnull lookup with non-boolean values as the right-hand side is deprecated, use True or False instead.

  • The barely documented django.db.models.query_utils.InvalidQuery exception class is deprecated in favor of FieldDoesNotExist and FieldError.

  • The django-admin.py entry point is deprecated in favor of django-admin.

  • The HttpRequest.is_ajax() method is deprecated as it relied on a jQuery-specific way of signifying AJAX calls, while current usage tends to use the JavaScript Fetch API. Depending on your use case, you can either write your own AJAX detection method, or use the new HttpRequest.accepts() method if your code depends on the client Accept HTTP header.

    If you are writing your own AJAX detection method, request.is_ajax() can be reproduced exactly as request.headers.get('x-requested-with') == 'XMLHttpRequest'.

  • Passing None as the first argument to django.utils.deprecation.MiddlewareMixin.__init__() is deprecated.

  • The encoding format of cookies values used by CookieStorage is different from the format generated by older versions of Django. Support for the old format remains until Django 4.0.

  • The encoding format of sessions is different from the format generated by older versions of Django. Support for the old format remains until Django 4.0.

  • The purely documentational providing_args argument for Signal is deprecated. If you rely on this argument as documentation, you can move the text to a code comment or docstring.

  • Calling django.utils.crypto.get_random_string() without a length argument is deprecated.

  • The list message for ModelMultipleChoiceField is deprecated in favor of invalid_list.

  • The passing of URL kwargs directly to the context by TemplateView is deprecated. Reference them in the template with view.kwargs instead.

  • Passing raw column aliases to QuerySet.order_by() is deprecated. The same result can be achieved by passing aliases in a RawSQL instead beforehand.

Features removed in 3.1

These features have reached the end of their deprecation cycle and are removed in Django 3.1.

See Features deprecated in 2.2 for details on these changes, including how to remove usage of these features.

  • django.utils.timezone.FixedOffset is removed.
  • django.core.paginator.QuerySetPaginator is removed.
  • A model’s Meta.ordering doesn’t affect GROUP BY queries.
  • django.contrib.postgres.fields.FloatRangeField and django.contrib.postgres.forms.FloatRangeField are removed.
  • The FILE_CHARSET setting is removed.
  • django.contrib.staticfiles.storage.CachedStaticFilesStorage is removed.
  • The RemoteUserBackend.configure_user() method requires request as the first positional argument.
  • Support for SimpleTestCase.allow_database_queries and TransactionTestCase.multi_db is removed.
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