============================================
Django 2.0 release notes - UNDER DEVELOPMENT
============================================

Welcome to Django 2.0!

These release notes cover the :ref:`new features <whats-new-2.0>`, as well as
some :ref:`backwards incompatible changes <backwards-incompatible-2.0>` you'll
want to be aware of when upgrading from Django 1.11 or earlier. We've
:ref:`dropped some features<removed-features-2.0>` that have reached the end of
their deprecation cycle, and we've :ref:`begun the deprecation process for some
features <deprecated-features-2.0>`.

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, and
  :lookup:`isvalid` lookup.

* 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.

: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.

: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() <django.core.files.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()
  <django.forms.Form.errors.get_json_data>` method returns form errors as
  a dictionary suitable for including in a JSON response.

Generic Views
~~~~~~~~~~~~~

* ...

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 <loading-fixtures-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.

Migrations
~~~~~~~~~~

* ...

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.

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`.

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
--------------------

* The ``DatabaseOperations.datetime_cast_date_sql()``,
  ``datetime_cast_time_sql()``, ``datetime_trunc_sql()``, and
  ``datetime_extract_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.

* 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)

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
<mysql-isolation-level>`, if needed.

:attr:`AbstractUser.last_name <django.contrib.auth.models.User.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.

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.

.. _deprecated-features-2.0:

Features deprecated in 2.0
==========================

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.
