============================================
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.

Migrations
~~~~~~~~~~

* The new :option:`migrate --plan` option prints the list of migration
  operations that will be performed.

Models
~~~~~~

* Added support for PostgreSQL operator classes (:attr:`.Index.opclasses`).

* 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.

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
~~~~~~~~~~

* ...

.. _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``.

:mod:`django.contrib.gis`
-------------------------

* Support for GDAL 1.9 and 1.10 is dropped.

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.

.. _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.
