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Django 3.0 release notes - UNDER DEVELOPMENT

Expected December 2019

Welcome to Django 3.0!

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 2.2 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 3.0 supports Python 3.6, 3.7, and 3.8. We highly recommend and only officially support the latest release of each series.

The Django 2.2.x series is the last to support Python 3.5.

Third-party library support for older version of Django

Following the release of Django 3.0, we suggest that third-party app authors drop support for all versions of Django prior to 2.2. At that time, you should be able to run your package’s tests using python -Wd so that deprecation warnings appear. After making the deprecation warning fixes, your app should be compatible with Django 3.0.

What’s new in Django 3.0

MariaDB support

Django now officially supports MariaDB 10.1 and higher. See MariaDB notes for more details.

ASGI support

Django 3.0 begins our journey to making Django fully async-capable by providing support for running as an ASGI application.

This is in addition to our existing WSGI support. Django intends to support both for the foreseeable future. Async features will only be available to applications that run under ASGI, however.

There is no need to switch your applications over unless you want to start experimenting with asynchronous code, but we have documentation on deploying with ASGI if you want to learn more.

Note that as a side-effect of this change, Django is now aware of asynchronous event loops and will block you calling code marked as “async unsafe” - such as ORM operations - from an asynchronous context. If you were using Django from async code before, this may trigger if you were doing it incorrectly. If you see a SynchronousOnlyOperation error, then closely examine your code and move any database operations to be in a synchronous child thread.

Exclusion constraints on PostgreSQL

The new ExclusionConstraint class enable adding exclusion constraints on PostgreSQL. Constraints are added to models using the Meta.constraints option.

Minor features

django.contrib.admin

  • Added support for the admin_order_field attribute on properties in ModelAdmin.list_display.
  • The new ModelAdmin.get_inlines() method allows specifying the inlines based on the request or model instance.
  • Select2 library is upgraded from version 4.0.3 to 4.0.7.
  • jQuery is upgraded from version 3.3.1 to 3.4.1.

django.contrib.auth

  • The new reset_url_token attribute in PasswordResetConfirmView allows specifying a token parameter displayed as a component of password reset URLs.
  • Added BaseBackend class to ease customization of authentication backends.
  • Added get_user_permissions() method to mirror the existing get_group_permissions() method.
  • Added HTML autocomplete attribute to widgets of username, email, and password fields in django.contrib.auth.forms for better interaction with browser password managers.
  • createsuperuser now falls back to environment variables for password and required fields, when a corresponding command line argument isn’t provided in non-interactive mode.

django.contrib.gis

  • Allowed MySQL spatial lookup functions to operate on real geometries. Previous support was limited to bounding boxes.
  • Added the GeometryDistance function, supported on PostGIS.
  • Added support for the furlong unit in Distance.
  • The GEOIP_PATH setting now supports pathlib.Path.
  • The GeoIP2 class now accepts pathlib.Path path.

django.contrib.postgres

django.contrib.sessions

django.contrib.syndication

Cache

CSRF

Email

File Storage

File Uploads

Forms

Generic Views

Internationalization

Management Commands

Migrations

Models

  • Added hash database functions MD5, SHA1, SHA224, SHA256, SHA384, and SHA512.
  • Added the Sign database function.
  • The new is_dst parameter of the Trunc database functions determines the treatment of nonexistent and ambiguous datetimes.
  • connection.queries now shows COPY TO statements on PostgreSQL.
  • FilePathField now accepts a callable path.
  • Allowed symmetrical intermediate table for self-referential ManyToManyField.
  • The name attributes of CheckConstraint, UniqueConstraint, and Index now support app label and class interpolation using the '%(app_label)s' and '%(class)s' placeholders.
  • The new Field.descriptor_class attribute allows model fields to customize the get and set behavior by overriding their descriptors.
  • Avg and Sum now support the distinct argument.
  • Added SmallAutoField which acts much like an AutoField except that it only allows values under a certain (database-dependent) limit. Values from 1 to 32767 are safe in all databases supported by Django.
  • AutoField, BigAutoField, and SmallAutoField now inherit from IntegerField, BigIntegerField and SmallIntegerField respectively. System checks and validators are now also properly inherited.
  • FileField.upload_to now supports pathlib.Path.

Requests and Responses

  • Allowed HttpResponse to be initialized with memoryview content.
  • For use in, for example, Django templates, HttpRequest.headers now allows look ups using underscores (e.g. user_agent) in place of hyphens.

Serialization

Signals

Templates

Tests

  • The new test Client argument raise_request_exception allows controlling whether or not exceptions raised during the request should also be raised in the test. The value defaults to True for backwards compatibility. If it is False and an exception occurs, the test client will return a 500 response with the attribute exc_info, a tuple providing information of the exception that occurred.
  • Tests and test cases to run can be selected by test name pattern using the new test -k option.
  • HTML comparison, as used by assertHTMLEqual(), now treats text, character references, and entity references that refer to the same character as equivalent.
  • Django test runner now supports headless mode for selenium tests on supported browsers. Add the --headless option to enable this mode.
  • Django test runner now supports --start-at and --start-after options to run tests starting from a specific top-level module.
  • Django test runner now supports a --pdb option to spawn a debugger at each error or failure.

URLs

Validators

Backwards incompatible changes in 3.0

Database backend API

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

  • The second argument of DatabaseIntrospection.get_geometry_type() is now the row description instead of the column name.
  • DatabaseIntrospection.get_field_type() may no longer return tuples.
  • If the database can create foreign keys in the same SQL statement that adds a field, add SchemaEditor.sql_create_column_inline_fk with the appropriate SQL; otherwise, set DatabaseFeatures.can_create_inline_fk = False.
  • DatabaseFeatures.can_return_id_from_insert and can_return_ids_from_bulk_insert are renamed to can_return_columns_from_insert and can_return_rows_from_bulk_insert.
  • Database functions now handle datetime.timezone formats when created using datetime.timedelta instances (e.g. timezone(timedelta(hours=5)), which would output 'UTC+05:00'). Third-party backends should handle this format when preparing DateTimeField in datetime_cast_date_sql(), datetime_extract_sql(), etc.
  • DatabaseOperations.return_insert_id() now requires an additional field argument with the model field.
  • Entries for AutoField, BigAutoField, and SmallAutoField are added to DatabaseOperations.integer_field_ranges to support the integer range validators on these field types. Third-party backends may need to customize the default entries.

django.contrib.admin

  • Admin’s model history change messages now prefers more readable field labels instead of field names.

django.contrib.gis

  • Support for PostGIS 2.1 is removed.
  • Support for SpatiaLite 4.1 and 4.2 is removed.
  • Support for GDAL 1.11 and GEOS 3.4 is removed.

Dropped support for PostgreSQL 9.4

Upstream support for PostgreSQL 9.4 ends in December 2019. Django 3.0 supports PostgreSQL 9.5 and higher.

Dropped support for Oracle 12.1

Upstream support for Oracle 12.1 ends in July 2021. Django 2.2 will be supported until April 2022. Django 3.0 officially supports Oracle 12.2 and 18c.

Removed private Python 2 compatibility APIs

While Python 2 support was removed in Django 2.0, some private APIs weren’t removed from Django so that third party apps could continue using them until the Python 2 end-of-life.

Since we expect apps to drop Python 2 compatibility when adding support for Django 3.0, we’re removing these APIs at this time.

  • django.test.utils.str_prefix() - Strings don’t have ‘u’ prefixes in Python 3.
  • django.test.utils.patch_logger() - Use unittest.TestCase.assertLogs() instead.
  • django.utils.lru_cache.lru_cache() - Alias of functools.lru_cache().
  • django.utils.decorators.available_attrs() - This function returns functools.WRAPPER_ASSIGNMENTS.
  • django.utils.decorators.ContextDecorator - Alias of contextlib.ContextDecorator.
  • django.utils._os.abspathu() - Alias of os.path.abspath().
  • django.utils._os.upath() and npath() - These functions do nothing on Python 3.
  • django.utils.six - Remove usage of this vendored library or switch to six.
  • django.utils.encoding.python_2_unicode_compatible() - Alias of six.python_2_unicode_compatible().
  • django.utils.functional.curry() - Use functools.partial() or functools.partialmethod. See 5b1c389603a353625ae1603.
  • django.utils.safestring.SafeBytes - Unused since Django 2.0.

New default value for the FILE_UPLOAD_PERMISSIONS setting

In older versions, the FILE_UPLOAD_PERMISSIONS setting defaults to None. With the default FILE_UPLOAD_HANDLERS, this results in uploaded files having different permissions depending on their size and which upload handler is used.

FILE_UPLOAD_PERMISSION now defaults to 0o644 to avoid this inconsistency.

Miscellaneous

  • ContentType.__str__() now includes the model’s app_label to disambiguate model’s with the same name in different apps.
  • Because accessing the language in the session rather than in the cookie is deprecated, LocaleMiddleware no longer looks for the user’s language in the session and django.contrib.auth.logout() no longer preserves the session’s language after logout.
  • django.utils.html.escape() now uses html.escape() to escape HTML. This converts ' to ' instead of the previous equivalent decimal code '.
  • The django-admin test -k option now works as the unittest -k option rather than as a shortcut for --keepdb.
  • Support for pywatchman < 1.2.0 is removed.
  • HTML rendered by SelectDateWidget for required fields now have the placeholder attribute, which mainly may require some adjustments in tests that compare HTML.
  • urlencode() now encodes iterable values as they are when doseq=False, rather than iterating them, bringing it into line with the standard library urllib.parse.urlencode() function.
  • intword template filter now translates 1.0 as a singular phrase and all other numeric values as plural. This may be incorrect for some languages.
  • Assigning a value to a model’s ForeignKey or OneToOneField '_id' attribute now unsets the corresponding field. Accessing the field afterwards will result in a query.
  • patch_vary_headers() now handles an asterisk '*' according to RFC 7231#section-7.1.4, i.e. if a list of header field names contains an asterisk, then the Vary header will consist of a single asterisk '*'.
  • SECURE_CONTENT_TYPE_NOSNIFF setting now defaults to True. With the enabled SECURE_CONTENT_TYPE_NOSNIFF, the SecurityMiddleware sets the X-Content-Type-Options: nosniff header on all responses that do not already have it.

Features deprecated in 3.0

django.utils.encoding.force_text() and smart_text()

The smart_text() and force_text() aliases (since Django 2.0) of smart_str() and force_str() are deprecated. Ignore this deprecation if your code supports Python 2 as the behavior of smart_str() and force_str() is different there.

Miscellaneous

Features removed in 3.0

These features have reached the end of their deprecation cycle and are removed in Django 3.0.

See Features deprecated in 2.0 for details on these changes, including how to remove usage of these features.

  • The django.db.backends.postgresql_psycopg2 module is removed.
  • django.shortcuts.render_to_response() is removed.
  • The DEFAULT_CONTENT_TYPE setting is removed.
  • HttpRequest.xreadlines() is removed.
  • Support for the context argument of Field.from_db_value() and Expression.convert_value() is removed.
  • The field_name keyword argument of QuerySet.earliest() and latest() is removed.

See Features deprecated in 2.1 for details on these changes, including how to remove usage of these features.

  • The ForceRHR GIS function is removed.
  • django.utils.http.cookie_date() is removed.
  • The staticfiles and admin_static template tag libraries are removed.
  • django.contrib.staticfiles.templatetags.staticfiles.static() is removed.
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