============================================ Django 2.0 release notes - UNDER DEVELOPMENT ============================================ Welcome to Django 2.0! These release notes cover the :ref:`new features `, as well as some :ref:`backwards incompatible changes ` you'll want to be aware of when upgrading from Django 1.11 or earlier. We've :ref:`dropped some features` that have reached the end of their deprecation cycle, and we've :ref:`begun the deprecation process for some features `. See the :doc:`/howto/upgrade-version` guide if you're updating an existing project. Python compatibility ==================== Django 2.0 supports Python 3.5+. Since Django 1.11, support for Python 2.7 and 3.4 is removed. We **highly recommend** and only officially support the latest release of each series. Third-party library support for older version of Django ======================================================= Following the release of Django 2.0, we suggest that third-party app authors drop support for all versions of Django prior to 1.11. At that time, you should be able run your package's tests using ``python -Wd`` so that deprecation warnings do appear. After making the deprecation warning fixes, your app should be compatible with Django 2.0. .. _whats-new-2.0: What's new in Django 2.0 ======================== Minor features -------------- :mod:`django.contrib.admin` ~~~~~~~~~~~~~~~~~~~~~~~~~~~ * ... :mod:`django.contrib.admindocs` ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ * ... :mod:`django.contrib.auth` ~~~~~~~~~~~~~~~~~~~~~~~~~~ * The default iteration count for the PBKDF2 password hasher is increased from 36,000 to 100,000. :mod:`django.contrib.contenttypes` ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ * ... :mod:`django.contrib.gis` ~~~~~~~~~~~~~~~~~~~~~~~~~ * Added MySQL support for the :class:`~django.contrib.gis.db.models.functions.AsGeoJSON` function, :class:`~django.contrib.gis.db.models.functions.GeoHash` function, :class:`~django.contrib.gis.db.models.functions.IsValid` function, :lookup:`isvalid` lookup, and :ref:`distance lookups `. * Added the :class:`~django.contrib.gis.db.models.functions.Azimuth` and :class:`~django.contrib.gis.db.models.functions.LineLocatePoint` functions, supported on PostGIS and SpatiaLite. * Any :class:`~django.contrib.gis.geos.GEOSGeometry` imported from GeoJSON now has its SRID set. * Added the :attr:`.OSMWidget.default_zoom` attribute to customize the map's default zoom level. * Made metadata readable and editable on rasters through the :attr:`~django.contrib.gis.gdal.GDALRaster.metadata`, :attr:`~django.contrib.gis.gdal.GDALRaster.info`, and :attr:`~django.contrib.gis.gdal.GDALBand.metadata` attributes. * Allowed passing driver-specific creation options to :class:`~django.contrib.gis.gdal.GDALRaster` objects using ``papsz_options``. * Allowed creating :class:`~django.contrib.gis.gdal.GDALRaster` objects in GDAL's internal virtual filesystem. Rasters can now be :ref:`created from and converted to binary data ` in-memory. :mod:`django.contrib.messages` ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ * ... :mod:`django.contrib.postgres` ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ * The new ``distinct`` argument for :class:`~django.contrib.postgres.aggregates.ArrayAgg` determines if concatenated values will be distinct. * The new :class:`~django.contrib.postgres.functions.RandomUUID` database function returns a version 4 UUID. It requires use of PostgreSQL's ``pgcrypto`` extension which can be activated using the new :class:`~django.contrib.postgres.operations.CryptoExtension` migration operation. * :class:`django.contrib.postgres.indexes.GinIndex` now supports the ``fast_update`` and ``gin_pending_list_limit`` parameters. :mod:`django.contrib.redirects` ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ * ... :mod:`django.contrib.sessions` ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ * ... :mod:`django.contrib.sitemaps` ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ * Added the ``protocol`` keyword argument to the :class:`~django.contrib.sitemaps.GenericSitemap` constructor. :mod:`django.contrib.sites` ~~~~~~~~~~~~~~~~~~~~~~~~~~~ * ... :mod:`django.contrib.staticfiles` ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ * ... :mod:`django.contrib.syndication` ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ * ... Cache ~~~~~ * ... CSRF ~~~~ * ... Database backends ~~~~~~~~~~~~~~~~~ * ... Email ~~~~~ * ... File Storage ~~~~~~~~~~~~ * :meth:`File.open() ` can be used as a context manager, e.g. ``with file.open() as f:``. File Uploads ~~~~~~~~~~~~ * ... Forms ~~~~~ * The new ``date_attrs`` and ``time_attrs`` arguments for :class:`~django.forms.SplitDateTimeWidget` and :class:`~django.forms.SplitHiddenDateTimeWidget` allow specifying different HTML attributes for the ``DateInput`` and ``TimeInput`` (or hidden) subwidgets. * The new :meth:`Form.errors.get_json_data() ` method returns form errors as a dictionary suitable for including in a JSON response. Generic Views ~~~~~~~~~~~~~ * The new :attr:`.ContextMixin.extra_context` attribute allows adding context in ``View.as_view()``. Internationalization ~~~~~~~~~~~~~~~~~~~~ * ... Management Commands ~~~~~~~~~~~~~~~~~~~ * :djadmin:`inspectdb` now translates MySQL's unsigned integer columns to ``PositiveIntegerField`` or ``PositiveSmallIntegerField``. * The new :option:`makemessages --add-location` option controls the comment format in PO files. * :djadmin:`loaddata` can now :ref:`read from stdin `. * The new :option:`diffsettings --output` option allows formatting the output in a unified diff format. * On Oracle, :djadmin:`inspectdb` can now introspect ``AutoField`` if the column is created as an identity column. * On MySQL, :djadmin:`dbshell` now supports client-side TLS certificates. Migrations ~~~~~~~~~~ * The new :option:`squashmigrations --squashed-name` option allows naming the squashed migration. Models ~~~~~~ * The new :class:`~django.db.models.functions.StrIndex` database function finds the starting index of a string inside another string. * On Oracle, ``AutoField`` and ``BigAutoField`` are now created as `identity columns`_. .. _`identity columns`: https://docs.oracle.com/database/121/DRDAA/migr_tools_feat.htm#DRDAA109 * The new ``chunk_size`` parameter of :meth:`.QuerySet.iterator` controls the number of rows fetched by the Python database client when streaming results from the database. For databases that don't support server-side cursors, it controls the number of results Django fetches from the database adapter. * Added the :class:`~django.db.models.functions.datetime.ExtractQuarter` function to extract the quarter from :class:`~django.db.models.DateField` and :class:`~django.db.models.DateTimeField`, and exposed it through the :lookup:`quarter` lookup. * Added the :class:`~django.db.models.functions.datetime.TruncQuarter` function to truncate :class:`~django.db.models.DateField` and :class:`~django.db.models.DateTimeField` to the first day of a quarter. * Added the :attr:`~django.db.models.Index.db_tablespace` parameter to class-based indexes. * If the database supports a native duration field (Oracle and PostgreSQL), :class:`~django.db.models.functions.datetime.Extract` now works with :class:`~django.db.models.DurationField`. * Added the ``of`` argument to :meth:`.QuerySet.select_for_update()`, supported on PostgreSQL and Oracle, to lock only rows from specific tables rather than all selected tables. It may be helpful particularly when :meth:`~.QuerySet.select_for_update()` is used in conjunction with :meth:`~.QuerySet.select_related()`. * The new ``field_name`` parameter of :meth:`.QuerySet.in_bulk` allows fetching results based on any unique model field. Requests and Responses ~~~~~~~~~~~~~~~~~~~~~~ * The :djadmin:`runserver` Web server supports HTTP 1.1. Serialization ~~~~~~~~~~~~~ * ... Signals ~~~~~~~ * ... Templates ~~~~~~~~~ * To increase the usefulness of :meth:`.Engine.get_default` in third-party apps, it now returns the first engine if multiple ``DjangoTemplates`` engines are configured in ``TEMPLATES`` rather than raising ``ImproperlyConfigured``. * Custom template tags may now accept keyword-only arguments. Tests ~~~~~ * Added threading support to :class:`~django.test.LiveServerTestCase`. * Added settings that allow customizing the test tablespace parameters for Oracle: :setting:`DATAFILE_SIZE`, :setting:`DATAFILE_TMP_SIZE`, :setting:`DATAFILE_EXTSIZE`, and :setting:`DATAFILE_TMP_EXTSIZE`. URLs ~~~~ * ... Validators ~~~~~~~~~~ * ... .. _backwards-incompatible-2.0: Backwards incompatible changes in 2.0 ===================================== Removed support for bytestrings in some places ---------------------------------------------- To support native Python 2 strings, older Django versions had to accept both bytestrings and unicode strings. Now that Python 2 support is dropped, bytestrings should only be encountered around input/output boundaries (handling of binary fields or HTTP streams, for example). You might have to update your code to limit bytestring usage to a minimum, as Django no longer accepts bytestrings in certain code paths. Database backend API -------------------- This section describes changes that may be needed in third-party database backends. * The ``DatabaseOperations.datetime_cast_date_sql()``, ``datetime_cast_time_sql()``, ``datetime_trunc_sql()``, ``datetime_extract_sql()``, and ``date_interval_sql()`` methods now return only the SQL to perform the operation instead of SQL and a list of parameters. * Third-party database backends should add a ``DatabaseWrapper.display_name`` attribute with the name of the database that your backend works with. Django may use it in various messages, such as in system checks. * The first argument of ``SchemaEditor._alter_column_type_sql()`` is now ``model`` rather than ``table``. * The first argument of ``SchemaEditor._create_index_name()`` is now ``table_name`` rather than ``model``. * To enable ``FOR UPDATE OF`` support, set ``DatabaseFeatures.has_select_for_update_of = True``. If the database requires that the arguments to ``OF`` be columns rather than tables, set ``DatabaseFeatures.select_for_update_of_column = True``. * Third-party database backends should add a ``DatabaseOperations.cast_char_field_without_max_length`` attribute with the database data type that will be used in the :class:`~django.db.models.functions.Cast` function for a ``CharField`` if the ``max_length`` argument isn't provided. Dropped support for Oracle 11.2 ------------------------------- The end of upstream support for Oracle 11.2 is Dec. 2020. Django 1.11 will be supported until April 2020 which almost reaches this date. Django 2.0 officially supports Oracle 12.1+. Default MySQL isolation level is read committed ----------------------------------------------- MySQL's default isolation level, repeatable read, may cause data loss in typical Django usage. To prevent that and for consistency with other databases, the default isolation level is now read committed. You can use the :setting:`DATABASES` setting to :ref:`use a different isolation level `, if needed. :attr:`AbstractUser.last_name ` ``max_length`` increased to 150 ---------------------------------------------------------------------------------------------------------- A migration for :attr:`django.contrib.auth.models.User.last_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 last names, use a custom form:: from django.contrib.auth.forms import UserChangeForm class MyUserChangeForm(UserChangeForm): last_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) ``QuerySet.reverse()`` and ``last()`` are prohibited after slicing ------------------------------------------------------------------ Calling ``QuerySet.reverse()`` or ``last()`` on a sliced queryset leads to unexpected results due to the slice being applied after reordering. This is now prohibited, e.g.:: >>> Model.objects.all()[:2].reverse() Traceback (most recent call last): ... TypeError: Cannot reverse a query once a slice has been taken. Form fields no longer accept optional arguments as positional arguments ----------------------------------------------------------------------- To help prevent runtime errors due to incorrect ordering of form field arguments, optional arguments of built-in form fields are no longer accepted as positional arguments. For example:: forms.IntegerField(25, 10) raises an exception and should be replaced with:: forms.IntegerField(max_value=25, min_value=10) ``call_command()`` validates the options it receives ---------------------------------------------------- ``call_command()`` now validates that the argument parser of the command being called defines all of the options passed to ``call_command()``. For custom management commands that use options not created using ``parser.add_argument()``, add a ``stealth_options`` attribute on the command:: class MyCommand(BaseCommand): stealth_options = ('option_name', ...) Indexes no longer accept positional arguments --------------------------------------------- For example:: models.Index(['headline', '-pub_date'], 'index_name') raises an exception and should be replaced with:: models.Index(fields=['headline', '-pub_date'], name='index_name') Foreign key constraints are now enabled on SQLite ------------------------------------------------- This will appear as a backwards-incompatible change (``IntegrityError: FOREIGN KEY constraint failed``) if attempting to save an existing model instance that's violating a foreign key constraint. Foreign keys are now created with ``DEFERRABLE INITIALLY DEFERRED`` instead of ``DEFERRABLE IMMEDIATE``. Thus, tables may need to be rebuilt to recreate foreign keys with the new definition, particularly if you're using a pattern like this:: from django.db import transaction with transaction.atomic(): Book.objects.create(author_id=1) Author.objects.create(id=1) If you don't recreate the foreign key as ``DEFERRED``, the first ``create()`` would fail now that foreign key constraints are enforced. Backup your database first! After upgrading to Django 2.0, you can then rebuild tables using a script similar to this:: from django.apps import apps from django.db import connection for app in apps.get_app_configs(): for model in app.get_models(include_auto_created=True): if model._meta.managed and not (model._meta.proxy or model._meta.swapped): for base in model.__bases__: if hasattr(base, '_meta'): base._meta.local_many_to_many = [] model._meta.local_many_to_many = [] with connection.schema_editor() as editor: editor._remake_table(model) This script hasn't received extensive testing and needs adaption for various cases such as multiple databases. Feel free to contribute improvements. Miscellaneous ------------- * The ``SessionAuthenticationMiddleware`` class is removed. It provided no functionality since session authentication is unconditionally enabled in Django 1.10. * The default HTTP error handlers (``handler404``, etc.) are now callables instead of dotted Python path strings. Django favors callable references since they provide better performance and debugging experience. * :class:`~django.views.generic.base.RedirectView` no longer silences ``NoReverseMatch`` if the ``pattern_name`` doesn't exist. * When :setting:`USE_L10N` is off, :class:`~django.forms.FloatField` and :class:`~django.forms.DecimalField` now respect :setting:`DECIMAL_SEPARATOR` and :setting:`THOUSAND_SEPARATOR` during validation. For example, with the settings:: USE_L10N = False USE_THOUSAND_SEPARATOR = True DECIMAL_SEPARATOR = ',' THOUSAND_SEPARATOR = '.' an input of ``"1.345"`` is now converted to ``1345`` instead of ``1.345``. * Subclasses of :class:`~django.contrib.auth.models.AbstractBaseUser` are no longer required to implement ``get_short_name()`` and ``get_full_name()``. (The base implementations that raise ``NotImplementedError`` are removed.) ``django.contrib.admin`` uses these methods if implemented but doesn't require them. Third-party apps that use these methods may want to adopt a similar approach. * The ``FIRST_DAY_OF_WEEK`` and ``NUMBER_GROUPING`` format settings are now kept as integers in JavaScript and JSON i18n view outputs. * :meth:`~django.test.TransactionTestCase.assertNumQueries` now ignores connection configuration queries. Previously, if a test opened a new database connection, those queries could be included as part of the ``assertNumQueries()`` count. * The ``PASSWORD_RESET_TIMEOUT_DAYS`` setting is more properly respected in ``contrib.auth`` password reset. Previously, resets were allowed for one day longer than expected. For example, with the default of ``PASSWORD_RESET_TIMEOUT_DAYS = 3``, password reset tokens are now valid for 72 hours rather than 96 hours. * The default size of the Oracle test tablespace is increased from 20M to 50M and the default autoextend size is increased from 10M to 25M. * To improve performance when streaming large result sets from the database, :meth:`.QuerySet.iterator` now fetches 2000 rows at a time instead of 100. The old behavior can be restored using the ``chunk_size`` parameter. For example:: Book.objects.iterator(chunk_size=100) * Providing unknown package names in the ``packages`` argument of the :class:`~django.views.i18n.JavaScriptCatalog` view now raises ``ValueError`` instead of passing silently. * A model instance's primary key now appears in the default ``Model.__str__()`` method, e.g. ``Question object (1)``. * ``makemigrations`` now detects changes to the model field ``limit_choices_to`` option. Add this to your existing migrations or accept an auto-generated migration for fields that use it. * Performing queries that require :ref:`automatic spatial transformations ` now raises ``NotImplementedError`` on MySQL instead of silently using non-transformed geometries. * ``django.core.exceptions.DjangoRuntimeWarning`` is removed. It was only used in the cache backend as an intermediate class in ``CacheKeyWarning``'s inheritance of ``RuntimeWarning``. * Renamed ``BaseExpression._output_field`` to ``output_field``. You may need to update custom expressions. * In older versions, forms and formsets combine their ``Media`` with widget ``Media`` by concatenating the two. The combining now tries to :ref:`preserve the relative order of elements in each list `. ``MediaOrderConflictWarning`` is issued if the order can't be preserved. .. _deprecated-features-2.0: Features deprecated in 2.0 ========================== ``context`` argument of ``Field.from_db_value()`` and ``Expression.convert_value()`` ------------------------------------------------------------------------------------ The ``context`` argument of ``Field.from_db_value()`` and ``Expression.convert_value()`` is unused as it's always an empty dictionary. The signature of both methods is now:: (self, value, expression, connection) instead of:: (self, value, expression, connection, context) Support for the old signature in custom fields and expressions remains until Django 3.0. Miscellaneous ------------- * The ``django.db.backends.postgresql_psycopg2`` module is deprecated in favor of ``django.db.backends.postgresql``. It's been an alias since Django 1.9. This only affects code that imports from the module directly. The ``DATABASES`` setting can still use ``'django.db.backends.postgresql_psycopg2'``, though you can simplify that by using the ``'django.db.backends.postgresql'`` name added in Django 1.9. * ``django.shortcuts.render_to_response()`` is deprecated in favor of :func:`django.shortcuts.render`. ``render()`` takes the same arguments except that is also requires a ``request``. * The ``DEFAULT_CONTENT_TYPE`` setting is deprecated. It doesn't interact well well with third-party apps and is obsolete since HTML5 has mostly superseded XHTML. * ``HttpRequest.xreadlines()`` is deprecated in favor of iterating over the request. .. _removed-features-2.0: Features removed in 2.0 ======================= These features have reached the end of their deprecation cycle and are removed in Django 2.0. See :ref:`deprecated-features-1.9` and :ref:`deprecated-features-1.10` for details, including how to remove usage of these features. * The ``weak`` argument to ``django.dispatch.signals.Signal.disconnect()`` is removed. * ``django.db.backends.base.BaseDatabaseOperations.check_aggregate_support()`` is removed. * The ``django.forms.extras`` package is removed. * The ``assignment_tag`` helper is removed. * The ``host`` argument to ``SimpleTestCase.assertsRedirects()`` is removed. The compatibility layer which allows absolute URLs to be considered equal to relative ones when the path is identical is also removed. * ``Field.rel`` and ``Field.remote_field.to`` are removed. * The ``on_delete`` argument for ``ForeignKey`` and ``OneToOneField`` are now required. * ``django.db.models.fields.add_lazy_relation()`` is removed. * When time zone support is enabled, database backends that don't support time zones no longer convert aware datetimes to naive values in UTC anymore when such values are passed as parameters to SQL queries executed outside of the ORM, e.g. with ``cursor.execute()``. * ``django.contrib.auth.tests.utils.skipIfCustomUser()`` is removed. * The ``GeoManager`` and ``GeoQuerySet`` classes are removed. * The ``django.contrib.gis.geoip`` module is removed. * The ``supports_recursion`` check for template loaders is removed from: * ``django.template.engine.Engine.find_template()`` * ``django.template.loader_tags.ExtendsNode.find_template()`` * ``django.template.loaders.base.Loader.supports_recursion()`` * ``django.template.loaders.cached.Loader.supports_recursion()`` * The ``load_template`` and ``load_template_sources`` template loader methods are removed. * The ``template_dirs`` argument for template loaders is removed: * ``django.template.loaders.base.Loader.get_template()`` * ``django.template.loaders.cached.Loader.cache_key()`` * ``django.template.loaders.cached.Loader.get_template()`` * ``django.template.loaders.cached.Loader.get_template_sources()`` * ``django.template.loaders.filesystem.Loader.get_template_sources()`` * ``django.template.loaders.base.Loader.__call__()`` is removed. * Support for custom error views that don't accept an ``exception`` parameter is removed. * The ``mime_type`` attribute of ``django.utils.feedgenerator.Atom1Feed`` and ``django.utils.feedgenerator.RssFeed`` is removed. * The ``app_name`` argument to ``include()`` is removed. * Support for passing a 3-tuple (including ``admin.site.urls``) as the first argument to ``include()`` is removed. * Support for setting a URL instance namespace without an application namespace is removed. * ``Field._get_val_from_obj()`` is removed. * ``django.template.loaders.eggs.Loader`` is removed. * The ``current_app`` parameter to the ``contrib.auth`` function-based views is removed. * The ``callable_obj`` keyword argument to ``SimpleTestCase.assertRaisesMessage()`` is removed. * Support for the ``allow_tags`` attribute on ``ModelAdmin`` methods is removed. * The ``enclosure`` keyword argument to ``SyndicationFeed.add_item()`` is removed. * The ``django.template.loader.LoaderOrigin`` and ``django.template.base.StringOrigin`` aliases for ``django.template.base.Origin`` are removed. * The ``makemigrations --exit`` option is removed. * Support for direct assignment to a reverse foreign key or many-to-many relation is removed. * The ``get_srid()`` and ``set_srid()`` methods of ``django.contrib.gis.geos.GEOSGeometry`` are removed. * The ``get_x()``, ``set_x()``, ``get_y()``, ``set_y()``, ``get_z()``, and ``set_z()`` methods of ``django.contrib.gis.geos.Point`` are removed. * The ``get_coords()`` and ``set_coords()`` methods of ``django.contrib.gis.geos.Point`` are removed. * The ``cascaded_union`` property of ``django.contrib.gis.geos.MultiPolygon`` is removed. * ``django.utils.functional.allow_lazy()`` is removed. * The ``shell --plain`` option is removed. * The ``django.core.urlresolvers`` module is removed. * ``CommaSeparatedIntegerField`` is removed, except for support in historical migrations. * The template ``Context.has_key()`` method is removed. * Support for the ``django.core.files.storage.Storage.accessed_time()``, ``created_time()``, and ``modified_time()`` methods is removed. * Support for query lookups using the model name when ``Meta.default_related_name`` is set is removed. * The MySQL ``__search`` lookup is removed. * The shim for supporting custom related manager classes without a ``_apply_rel_filters()`` method is removed. * Using ``User.is_authenticated()`` and ``User.is_anonymous()`` as methods rather than properties is no longer supported. * The ``Model._meta.virtual_fields`` attribute is removed. * The keyword arguments ``virtual_only`` in ``Field.contribute_to_class()`` and ``virtual`` in ``Model._meta.add_field()`` are removed. * The ``javascript_catalog()`` and ``json_catalog()`` views are removed. * ``django.contrib.gis.utils.precision_wkt()`` is removed. * In multi-table inheritance, implicit promotion of a ``OneToOneField`` to a ``parent_link`` is removed. * Support for ``Widget._format_value()`` is removed. * ``FileField`` methods ``get_directory_name()`` and ``get_filename()`` are removed. * The ``mark_for_escaping()`` function and the classes it uses: ``EscapeData``, ``EscapeBytes``, ``EscapeText``, ``EscapeString``, and ``EscapeUnicode`` are removed. * The ``escape`` filter now uses ``django.utils.html.conditional_escape()``. * ``Manager.use_for_related_fields`` is removed. * Model ``Manager`` inheritance follows MRO inheritance rules. The requirement to use ``Meta.manager_inheritance_from_future`` to opt-in to the behavior is removed. * Support for old-style middleware using ``settings.MIDDLEWARE_CLASSES`` is removed.