Django 3.0 リリースノート

2019年12月2日

Django 3.0 へようこそ！

このリリースノートでは、 バージョン 3.0 の新機能 と、Django 2.2 以前からアップグレードする際に注意すべき、 後方互換性のない変更 について説明します。 非推奨サイクルが終了した機能を廃止しました 。また、 一部の機能を非推奨 としました。

既存のプロジェクトをアップデートするときは、 Django の新しいバージョンへの更新 ガイドに従ってください。

Python バージョン間の互換性

Django 3.0 は Python 3.6, 3.7, 3.8, 3.9 をサポートします（3.0.11現在）。各バージョン系列の最新リリースのみを公式にサポートし、最新リリースを使用することを 強く推奨 します。

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

古いバージョンの Django をサポートするサードパーティのライブラリ

Django 3.0 リリース後は、サードパーティアプリの開発者は 2.2 より前のバージョンの Django のサポートを終了することを推奨します。このとき、python -Wd を使ったパッケージテストを実行して、廃止予定 (deprecation) の警告を出力できます。廃止予定の警告が出ないように修正すれば、アプリケーションは Django 3.0 と互換性のある状態になっているはずです。

Django 3.0 の新機能

MariaDB のサポート

Django は新たに公式に MariaDB 10.1 以上をサポートするようになりました。詳しくは、 MariaDB ノート を参照してください。

ASGI のサポート

Django 3.0 から、ASGI アプリケーションとして実行できるようにすることによって、私たちは Django を完全な非同期処理が可能なフレームワークに作り変える旅を始めます。

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.

At this stage async support only applies to the outer ASGI application. Internally everything remains synchronous. Asynchronous middleware, views, etc. are not yet supported. You can, however, use ASGI middleware around Django's application, allowing you to combine Django with other ASGI frameworks.

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.

PostgreSQL における排他制約 (Exclusion constraints)

新しい ExclusionConstraint クラスでは、PostgreSQL への排他制約 (exclusion constraints) の追加を有効になります。制約は Meta.constraints オプションを用いてモデルに追加されます。

Filter expressions

Expressions that output BooleanField may now be used directly in QuerySet filters, without having to first annotate and then filter against the annotation.

Enumerations for model field choices

Custom enumeration types TextChoices, IntegerChoices, and Choices are now available as a way to define Field.choices. TextChoices and IntegerChoices types are provided for text and integer fields. The Choices class allows defining a compatible enumeration for other concrete data types. These custom enumeration types support human-readable labels that can be translated and accessed via a property on the enumeration or its members. See Enumeration types for more details and examples.

マイナーな機能

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 ライブラリのバージョンが 4.0.3 から 4.0.7 にアップグレードされました。

• jQuery のバージョンが 3.3.1 から 3.4.1 にアップグレードされました。

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.

• REQUIRED_FIELDS now supports ManyToManyFields.

• The new UserManager.with_perm() method returns users that have the specified permission.

• PBKDF2 パスワードハッシュに対するデフォルトのイテレーション回数が 150,000 から 180,000 に増加しました。

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

• The new RangeOperators helps to avoid typos in SQL operators that can be used together with RangeField.

• The new RangeBoundary expression represents the range boundaries.

• The new AddIndexConcurrently and RemoveIndexConcurrently classes allow creating and dropping indexes CONCURRENTLY on PostgreSQL.

django.contrib.sessions

• The new get_session_cookie_age() method allows dynamically specifying the session cookie age.

django.contrib.syndication

• Added the language class attribute to the django.contrib.syndication.views.Feed to customize a feed language. The default value is get_language() instead of LANGUAGE_CODE.

キャッシュ

• add_never_cache_headers() and never_cache() now add the private directive to Cache-Control headers.

ファイルストレージ

• The new Storage.get_alternative_name() method allows customizing the algorithm for generating filenames if a file with the uploaded name already exists.

フォーム

• Formsets may control the widget used when ordering forms via can_order by setting the ordering_widget attribute or overriding get_ordering_widget.

国際化 (internationalization)

• Added the LANGUAGE_COOKIE_HTTPONLY, LANGUAGE_COOKIE_SAMESITE, and LANGUAGE_COOKIE_SECURE settings to set the HttpOnly, SameSite, and Secure flags on language cookies. The default values of these settings preserve the previous behavior.

• Added support and translations for the Uzbek language.

ロギング

• The new reporter_class parameter of AdminEmailHandler allows providing an django.views.debug.ExceptionReporter subclass to customize the traceback text sent to site ADMINS when DEBUG is False.

管理コマンド

• The new compilemessages --ignore option allows ignoring specific directories when searching for .po files to compile.

• showmigrations --list now shows the applied datetimes when --verbosity is 2 and above.

• On PostgreSQL, dbshell now supports client-side TLS certificates.

• inspectdb now introspects OneToOneField when a foreign key has a unique or primary key constraint.

• The new --skip-checks option skips running system checks prior to running the command.

• The startapp --template and startproject --template options now support templates stored in XZ archives (.tar.xz, .txz) and LZMA archives (.tar.lzma, .tlz).

モデル

• 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 for 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.

• CheckConstraint is now supported on MySQL 8.0.16+.

• The new allows_group_by_selected_pks_on_model() method of django.db.backends.base.BaseDatabaseFeatures allows optimization of GROUP BY clauses to require only the selected models' primary keys. By default, it's supported only for managed models on PostgreSQL.

  To enable the GROUP BY primary key-only optimization for unmanaged models, you have to subclass the PostgreSQL database engine, overriding the features class allows_group_by_selected_pks_on_model() method as you require. See Subclassing the built-in database backends for an example.

Request と Response

• Allowed HttpResponse to be initialized with memoryview content.

• For use in, for example, Django templates, HttpRequest.headers now allows lookups using underscores (e.g. user_agent) in place of hyphens.

セキュリティ

• X_FRAME_OPTIONS now defaults to 'DENY'. In older versions, the X_FRAME_OPTIONS setting defaults to 'SAMEORIGIN'. If your site uses frames of itself, you will need to explicitly set X_FRAME_OPTIONS = 'SAMEORIGIN' for them to continue working.

• SECURE_CONTENT_TYPE_NOSNIFF がデフォルトで True になりました。この設定を有効にすることにより、 SecurityMiddleware が X-Content-Type-Options: nosniff ヘッダを付与されていなかった全レスポンスにこのヘッダを付与することになります。

• SecurityMiddleware can now send the Referrer-Policy header.

テスト

• 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.

• DiscoverRunner can now spawn a debugger at each error or failure using the test --pdb option.

3.0 における後方互換性のない変更

Model.save() when providing a default for the primary key

Model.save() no longer attempts to find a row when saving a new Model instance and a default value for the primary key is provided, and always performs a single INSERT query. In older Django versions, Model.save() performed either an INSERT or an UPDATE based on whether or not the row exists.

This makes calling Model.save() while providing a default primary key value equivalent to passing force_insert=True to model's save(). Attempts to use a new Model instance to update an existing row will result in an IntegrityError.

In order to update an existing model for a specific primary key value, use the update_or_create() method or QuerySet.filter(pk=…).update(…) instead. For example:

>>> MyModel.objects.update_or_create(pk=existing_pk, defaults={"name": "new name"})
>>> MyModel.objects.filter(pk=existing_pk).update(name="new name")

データベースバックエンド API

このセクションでは、サードパーティのデータベースバックエンドで必要になる可能性のある変更について説明します。

• 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.

• 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.

• DatabaseOperations.fetch_returned_insert_id() is replaced by fetch_returned_insert_columns() which returns a list of values returned by the INSERT … RETURNING statement, instead of a single value.

• DatabaseOperations.return_insert_id() is replaced by return_insert_columns() that accepts a fields argument, which is an iterable of fields to be returned after insert. Usually this is only the auto-generated primary key.

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

2019年12月に PostgreSQL 9.4 に対する upstream のサポートが終了しました。これに伴い、Django 3.0 からは PostgreSQL 9.5 以降のみをサポートします。

Dropped support for Oracle 12.1

Oracle 12.1 の upstream のサポートが2021年7月に終了します。Django2.2 は2022年4月までサポートされます。Django 3.0 は、公式には Oracle 12.1 と 18c をサポートします。

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.

Django アプリが Django 3.0 をサポートに加える時点で、アプリの Python 2 との後方互換性が失われると考えられます。そのため、これらの API はこの時点で削除されます。

• 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 - このベンダリングされたライブラリの使用を止めて、 six に切り替えてください。

• 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 5b1c389603a353625ae1603ba345147356336afb.

• 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_PERMISSIONS now defaults to 0o644 to avoid this inconsistency.

New default values for security settings

To make Django projects more secure by default, some security settings now have more secure default values:

• X_FRAME_OPTIONS now defaults to 'DENY'.

• SECURE_CONTENT_TYPE_NOSNIFF now defaults to True.

これらの変更の詳細については、What's New Security section を見てください。

その他

• ContentType.__str__() now includes the model's app_label to disambiguate models 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.

• 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 afterward 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 '*'.

• On MySQL 8.0.16+, PositiveIntegerField and PositiveSmallIntegerField now include a check constraint to prevent negative values in the database.

• alias=None is added to the signature of Expression.get_group_by_cols().

• RegexPattern, used by re_path(), no longer returns keyword arguments with None values to be passed to the view for the optional named groups that are missing.

3.0 で非推奨になった機能

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.

その他

• django.utils.http.urlquote(), urlquote_plus(), urlunquote(), and urlunquote_plus() are deprecated in favor of the functions that they're aliases for: urllib.parse.quote(), quote_plus(), unquote(), and unquote_plus().

• django.utils.translation.ugettext(), ugettext_lazy(), ugettext_noop(), ungettext(), and ungettext_lazy() are deprecated in favor of the functions that they're aliases for: django.utils.translation.gettext(), gettext_lazy(), gettext_noop(), ngettext(), and ngettext_lazy().

• To limit creation of sessions and hence favor some caching strategies, django.views.i18n.set_language() will stop setting the user's language in the session in Django 4.0. Since Django 2.1, the language is always stored in the LANGUAGE_COOKIE_NAME cookie.

• django.utils.text.unescape_entities() is deprecated in favor of html.unescape(). Note that unlike unescape_entities(), html.unescape() evaluates lazy strings immediately.

• To avoid possible confusion as to effective scope, the private internal utility is_safe_url() is renamed to url_has_allowed_host_and_scheme(). That a URL has an allowed host and scheme doesn't in general imply that it's "safe". It may still be quoted incorrectly, for example. Ensure to also use iri_to_uri() on the path component of untrusted URLs.

3.0 で削除された機能

以下の機能は、非推奨サイクルの終わりに達したため、Django 3.0 で削除されます。

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 2.1 で非推奨になった機能 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.