============================================
Django 2.2 release notes - UNDER DEVELOPMENT
============================================
*Expected April 2019*
Welcome to Django 2.2!
These release notes cover the :ref:`new features <whats-new-2.2>`, as well as
some :ref:`backwards incompatible changes <backwards-incompatible-2.2>` you'll
want to be aware of when upgrading from Django 2.1 or earlier. We've
:ref:`begun the deprecation process for some features
<deprecated-features-2.2>`.
See the :doc:`/howto/upgrade-version` guide if you're updating an existing
project.
Django 2.2 is designated as a :term:`long-term support release`. It will
receive security updates for at least three years after its release. Support
for the previous LTS, Django 1.11, will end in April 2020.
Python compatibility
====================
Django 2.2 supports Python 3.5, 3.6, and 3.7. We **highly recommend** and only
officially support the latest release of each series.
.. _whats-new-2.2:
What's new in Django 2.2
========================
Check Constraints
-----------------
The new :class:`~django.db.models.CheckConstraint` class enables adding custom
database constraints. Constraints are added to models using the
:attr:`Meta.constraints <django.db.models.Options.constraints>` option.
Minor features
--------------
:mod:`django.contrib.admin`
~~~~~~~~~~~~~~~~~~~~~~~~~~~
* ...
:mod:`django.contrib.admindocs`
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
* ...
:mod:`django.contrib.auth`
~~~~~~~~~~~~~~~~~~~~~~~~~~
* ...
:mod:`django.contrib.contenttypes`
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
* ...
:mod:`django.contrib.gis`
~~~~~~~~~~~~~~~~~~~~~~~~~
* Added Oracle support for the
:class:`~django.contrib.gis.db.models.functions.Envelope` function.
* Added SpatiaLite support for the :lookup:`coveredby` and :lookup:`covers`
lookups.
:mod:`django.contrib.messages`
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
* ...
:mod:`django.contrib.postgres`
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
* The new ``ordering`` argument for
:class:`~django.contrib.postgres.aggregates.ArrayAgg` and
:class:`~django.contrib.postgres.aggregates.StringAgg` determines the
ordering of the aggregated elements.
* The new :class:`~django.contrib.postgres.indexes.BTreeIndex`,
:class:`~django.contrib.postgres.indexes.HashIndex` and
:class:`~django.contrib.postgres.indexes.SpGistIndex` classes allow
creating ``B-Tree``, ``hash``, and ``SP-GiST`` indexes in the database.
* :class:`~django.contrib.postgres.indexes.BrinIndex` now has the
``autosummarize`` parameter.
* The new ``search_type`` parameter of
:class:`~django.contrib.postgres.search.SearchQuery` allows searching for
a phrase or raw expression.
:mod:`django.contrib.redirects`
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
* ...
:mod:`django.contrib.sessions`
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
* ...
:mod:`django.contrib.sitemaps`
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
* ...
:mod:`django.contrib.sites`
~~~~~~~~~~~~~~~~~~~~~~~~~~~
* ...
:mod:`django.contrib.staticfiles`
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
* Added path matching to the :option:`collectstatic --ignore` option so that
patterns like ``/vendor/*.js`` can be used.
:mod:`django.contrib.syndication`
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
* ...
Cache
~~~~~
* ...
CSRF
~~~~
* ...
Database backends
~~~~~~~~~~~~~~~~~
* Added result streaming for :meth:`.QuerySet.iterator` on SQLite.
Email
~~~~~
* ...
File Storage
~~~~~~~~~~~~
* ...
File Uploads
~~~~~~~~~~~~
* ...
Forms
~~~~~
* ...
Generic Views
~~~~~~~~~~~~~
* ...
Internationalization
~~~~~~~~~~~~~~~~~~~~
* ...
Management Commands
~~~~~~~~~~~~~~~~~~~
* The new :option:`--force-color` option forces colorization of the command
output.
* :djadmin:`inspectdb` now creates models for foreign tables on PostgreSQL.
* :option:`inspectdb --include-views` now creates models for materialized views
on PostgreSQL.
* :djadmin:`inspectdb` now introspects :class:`~django.db.models.DurationField`
for Oracle and PostgreSQL.
* On Oracle, :djadmin:`dbshell` is wrapped with ``rlwrap``, if available.
``rlwrap`` provides a command history and editing of keyboard input.
Migrations
~~~~~~~~~~
* The new :option:`migrate --plan` option prints the list of migration
operations that will be performed.
* ``NoneType`` can now be serialized in migrations.
Models
~~~~~~
* Added support for PostgreSQL operator classes (:attr:`.Index.opclasses`).
* Added support for partial indexes (:attr:`.Index.condition`).
* Added many :ref:`math database functions <math-functions>`.
* Setting the new ``ignore_conflicts`` parameter of
:meth:`.QuerySet.bulk_create` to ``True`` tells the database to ignore
failure to insert rows that fail uniqueness constraints or other checks.
* The new :class:`~django.db.models.functions.ExtractIsoYear` function extracts
ISO-8601 week-numbering years from :class:`~django.db.models.DateField` and
:class:`~django.db.models.DateTimeField`, and the new :lookup:`iso_year`
lookup allows querying by an ISO-8601 week-numbering year.
* The new :meth:`.QuerySet.bulk_update` method allows efficiently updating
specific fields on multiple model instances.
* Django no longer always starts a transaction when a single query is being
performed, such as ``Model.save()``, ``QuerySet.update()``, and
``Model.delete()``. This improves the performance of autocommit by reducing
the number of database round trips.
Requests and Responses
~~~~~~~~~~~~~~~~~~~~~~
* ...
Serialization
~~~~~~~~~~~~~
* You can now deserialize data using natural keys containing :ref:`forward
references <natural-keys-and-forward-references>` by passing
``handle_forward_references=True`` to ``serializers.deserialize()``.
Additionally, :djadmin:`loaddata` handles forward references automatically.
Signals
~~~~~~~
* ...
Templates
~~~~~~~~~
* ...
Tests
~~~~~
* The new :meth:`.SimpleTestCase.assertURLEqual` assertion checks for a given
URL, ignoring the ordering of the query string.
:meth:`~.SimpleTestCase.assertRedirects` uses the new assertion.
* The test :class:`~.django.test.Client` now supports automatic JSON
serialization of list and tuple ``data`` when
``content_type='application/json'``.
URLs
~~~~
* ...
Validators
~~~~~~~~~~
* :class:`.MaxValueValidator`, :class:`.MinValueValidator`,
:class:`.MinLengthValidator`, and :class:`.MaxLengthValidator` now accept
a callable ``limit_value``.
.. _backwards-incompatible-2.2:
Backwards incompatible changes in 2.2
=====================================
Database backend API
--------------------
* Third-party database backends must implement support for table check
constraints or set ``DatabaseFeatures.supports_table_check_constraints`` to
``False``.
* Third party database backends must implement support for ignoring
constraints or uniqueness errors while inserting or set
``DatabaseFeatures.supports_ignore_conflicts`` to ``False``.
* Third party database backends must implement introspection for
``DurationField`` or set ``DatabaseFeatures.can_introspect_duration_field``
to ``False``.
* ``DatabaseFeatures.uses_savepoints`` now defaults to ``True``.
* Third party database backends must implement support for partial indexes or
set ``DatabaseFeatures.supports_partial_indexes`` to ``False``.
Admin actions are no longer collected from base ``ModelAdmin`` classes
----------------------------------------------------------------------
For example, in older versions of Django::
from django.contrib import admin
class BaseAdmin(admin.ModelAdmin):
actions = ['a']
class SubAdmin(BaseAdmin):
actions = ['b']
``SubAdmin`` will have actions ``'a'`` and ``'b'``.
Now ``actions`` follows standard Python inheritance. To get the same result as
before::
class SubAdmin(BaseAdmin):
actions = BaseAdmin.actions + ['b']
:mod:`django.contrib.gis`
-------------------------
* Support for GDAL 1.9 and 1.10 is dropped.
``TransactionTestCase`` serialized data loading
-----------------------------------------------
Initial data migrations are now loaded in
:class:`~django.test.TransactionTestCase` at the end of the test, after the
database flush. In older versions, this data was loaded at the beginning of the
test, but this prevents the :option:`test --keepdb` option from working
properly (the database was empty at the end of the whole test suite). This
change shouldn't have an impact on your tests unless you've customized
:class:`~django.test.TransactionTestCase`'s internals.
``sqlparse`` is required dependency
-----------------------------------
To simplify a few parts of Django's database handling, `sqlparse
<https://pypi.org/project/sqlparse/>`_ is now a required dependency. It's
automatically installed along with Django.
Miscellaneous
-------------
* To improve readability, the ``UUIDField`` form field now displays values with
dashes, e.g. ``550e8400-e29b-41d4-a716-446655440000`` instead of
``550e8400e29b41d4a716446655440000``.
* On SQLite, ``PositiveIntegerField`` and ``PositiveSmallIntegerField`` now
include a check constraint to prevent negative values in the database. If you
have existing invalid data and run a migration that recreates a table, you'll
see ``CHECK constraint failed``.
* For consistency with WSGI servers, the test client now sets the
``Content-Length`` header to a string rather than an integer.
* The return value of :func:`django.utils.text.slugify` is no longer marked as
HTML safe.
* The default truncation character used by the :tfilter:`urlizetrunc`,
:tfilter:`truncatechars`, :tfilter:`truncatechars_html`,
:tfilter:`truncatewords`, and :tfilter:`truncatewords_html` template filters
is now the real ellipsis character (``…``) instead of 3 dots. You may have to
adapt some test output comparisons.
* Support for bytestring paths in the template filesystem loader is removed.
* :func:`django.utils.http.urlsafe_base64_encode` now returns a string instead
of a bytestring, and :func:`django.utils.http.urlsafe_base64_decode` may no
longer be passed a bytestring.
* Support for ``cx_Oracle`` < 6.0 is removed.
.. _deprecated-features-2.2:
Features deprecated in 2.2
==========================
Model ``Meta.ordering`` will no longer affect ``GROUP BY`` queries
------------------------------------------------------------------
A model's ``Meta.ordering`` affecting ``GROUP BY`` queries (such as
``.annotate().values()``) is a common source of confusion. Such queries now
issue a deprecation warning with the advice to add an ``order_by()`` to retain
the current query. ``Meta.ordering`` will be ignored in such queries starting
in Django 3.1.
Miscellaneous
-------------
* ``django.utils.timezone.FixedOffset`` is deprecated in favor of
:class:`datetime.timezone`.
* The undocumented ``QuerySetPaginator`` alias of
``django.core.paginator.Paginator`` is deprecated.
* The ``FloatRangeField`` model and form fields in ``django.contrib.postgres``
are deprecated in favor of a new name, ``DecimalRangeField``, to match the
underlying ``numrange`` data type used in the database.
* The ``FILE_CHARSET`` setting is deprecated. Starting with Django 3.1, files
read from disk must be UTF-8 encoded.
* ``django.contrib.staticfiles.storage.CachedStaticFilesStorage`` is
deprecated due to the intractable problems that is has. Use
:class:`.ManifestStaticFilesStorage` or a third-party cloud storage instead.