mirror of
https://github.com/django/django.git
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bc7dd8490b
Checked the following locations:
* Model.save(): If there are parents involved, take the safe way and use
transactions since this should be an all or nothing operation.
If the model has no parents:
* Signals are executed before and after the previous existing
transaction -- they were never been part of the transaction.
* if `force_insert` is set then only one query is executed -> atomic
by definition and no transaction needed.
* same applies to `force_update`.
* If a primary key is set and no `force_*` is set Django will try an
UPDATE and if that returns zero rows it tries an INSERT. The first
case is completly save (single query). In the second case a
transaction should not produce different results since the update
query is basically a no-op then (might miss something though).
* QuerySet.update(): no signals issued, single query -> no transaction
needed.
* Model/Collector.delete(): This one is fun due to the fact that is
does many things at once.
Most importantly though: It does send signals as part of the
transaction, so for maximum backwards compatibility we need to be
conservative.
To ensure maximum compatibility the transaction here is removed only
if the following holds true:
* A single instance is being deleted.
* There are no signal handlers attached to that instance.
* There are no deletions/updates to cascade.
* There are no parents which also need deletion.
343 lines
8.8 KiB
Plaintext
343 lines
8.8 KiB
Plaintext
============================================
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Django 2.2 release notes - UNDER DEVELOPMENT
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============================================
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*Expected April 2019*
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Welcome to Django 2.2!
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These release notes cover the :ref:`new features <whats-new-2.2>`, as well as
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some :ref:`backwards incompatible changes <backwards-incompatible-2.2>` you'll
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want to be aware of when upgrading from Django 2.1 or earlier. We've
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:ref:`begun the deprecation process for some features
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<deprecated-features-2.2>`.
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See the :doc:`/howto/upgrade-version` guide if you're updating an existing
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project.
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Django 2.2 is designated as a :term:`long-term support release`. It will
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receive security updates for at least three years after its release. Support
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for the previous LTS, Django 1.11, will end in April 2020.
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Python compatibility
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====================
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Django 2.2 supports Python 3.5, 3.6, and 3.7. We **highly recommend** and only
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officially support the latest release of each series.
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.. _whats-new-2.2:
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What's new in Django 2.2
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========================
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Check Constraints
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-----------------
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The new :class:`~django.db.models.CheckConstraint` class enables adding custom
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database constraints. Constraints are added to models using the
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:attr:`Meta.constraints <django.db.models.Options.constraints>` option.
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Minor features
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--------------
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:mod:`django.contrib.admin`
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~~~~~~~~~~~~~~~~~~~~~~~~~~~
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* ...
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:mod:`django.contrib.admindocs`
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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* ...
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:mod:`django.contrib.auth`
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~~~~~~~~~~~~~~~~~~~~~~~~~~
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* ...
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:mod:`django.contrib.contenttypes`
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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* ...
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:mod:`django.contrib.gis`
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~~~~~~~~~~~~~~~~~~~~~~~~~
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* Added Oracle support for the
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:class:`~django.contrib.gis.db.models.functions.Envelope` function.
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* Added SpatiaLite support for the :lookup:`coveredby` and :lookup:`covers`
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lookups.
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:mod:`django.contrib.messages`
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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* ...
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:mod:`django.contrib.postgres`
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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* The new ``ordering`` argument for
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:class:`~django.contrib.postgres.aggregates.ArrayAgg` and
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:class:`~django.contrib.postgres.aggregates.StringAgg` determines the
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ordering of the aggregated elements.
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* The new :class:`~django.contrib.postgres.indexes.BTreeIndex`,
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:class:`~django.contrib.postgres.indexes.HashIndex` and
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:class:`~django.contrib.postgres.indexes.SpGistIndex` classes allow
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creating ``B-Tree``, ``hash``, and ``SP-GiST`` indexes in the database.
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* :class:`~django.contrib.postgres.indexes.BrinIndex` now has the
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``autosummarize`` parameter.
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* The new ``search_type`` parameter of
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:class:`~django.contrib.postgres.search.SearchQuery` allows searching for
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a phrase or raw expression.
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:mod:`django.contrib.redirects`
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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* ...
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:mod:`django.contrib.sessions`
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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* ...
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:mod:`django.contrib.sitemaps`
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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* ...
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:mod:`django.contrib.sites`
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~~~~~~~~~~~~~~~~~~~~~~~~~~~
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* ...
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:mod:`django.contrib.staticfiles`
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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* Added path matching to the :option:`collectstatic --ignore` option so that
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patterns like ``/vendor/*.js`` can be used.
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:mod:`django.contrib.syndication`
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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* ...
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Cache
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~~~~~
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* ...
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CSRF
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~~~~
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* ...
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Database backends
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~~~~~~~~~~~~~~~~~
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* Added result streaming for :meth:`.QuerySet.iterator` on SQLite.
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Email
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~~~~~
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* ...
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File Storage
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~~~~~~~~~~~~
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* ...
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File Uploads
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~~~~~~~~~~~~
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* ...
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Forms
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~~~~~
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* ...
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Generic Views
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~~~~~~~~~~~~~
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* ...
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Internationalization
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~~~~~~~~~~~~~~~~~~~~
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* ...
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Management Commands
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~~~~~~~~~~~~~~~~~~~
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* The new :option:`--force-color` option forces colorization of the command
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output.
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* :djadmin:`inspectdb` now creates models for foreign tables on PostgreSQL.
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* :option:`inspectdb --include-views` now creates models for materialized views
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on PostgreSQL.
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Migrations
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~~~~~~~~~~
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* The new :option:`migrate --plan` option prints the list of migration
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operations that will be performed.
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* ``NoneType`` can now be serialized in migrations.
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Models
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~~~~~~
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* Added support for PostgreSQL operator classes (:attr:`.Index.opclasses`).
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* Added many :ref:`math database functions <math-functions>`.
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* Setting the new ``ignore_conflicts`` parameter of
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:meth:`.QuerySet.bulk_create` to ``True`` tells the database to ignore
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failure to insert rows that fail uniqueness constraints or other checks.
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* The new :class:`~django.db.models.functions.ExtractIsoYear` function extracts
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ISO-8601 week-numbering years from :class:`~django.db.models.DateField` and
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:class:`~django.db.models.DateTimeField`, and the new :lookup:`iso_year`
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lookup allows querying by an ISO-8601 week-numbering year.
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* The new :meth:`.QuerySet.bulk_update` method allows efficiently updating
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specific fields on multiple model instances.
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* Django no longer always starts a transaction when a single query is being
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performed, such as ``Model.save()``, ``QuerySet.update()``, and
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``Model.delete()``. This improves the performance of autocommit by reducing
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the number of database round trips.
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Requests and Responses
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~~~~~~~~~~~~~~~~~~~~~~
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* ...
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Serialization
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~~~~~~~~~~~~~
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* You can now deserialize data using natural keys containing :ref:`forward
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references <natural-keys-and-forward-references>` by passing
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``handle_forward_references=True`` to ``serializers.deserialize()``.
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Additionally, :djadmin:`loaddata` handles forward references automatically.
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Signals
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~~~~~~~
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* ...
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Templates
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~~~~~~~~~
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* ...
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Tests
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~~~~~
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* The new :meth:`.SimpleTestCase.assertURLEqual` assertion checks for a given
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URL, ignoring the ordering of the query string.
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:meth:`~.SimpleTestCase.assertRedirects` uses the new assertion.
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* The test :class:`~.django.test.Client` now supports automatic JSON
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serialization of list and tuple ``data`` when
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``content_type='application/json'``.
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URLs
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~~~~
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* ...
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Validators
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~~~~~~~~~~
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* ...
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.. _backwards-incompatible-2.2:
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Backwards incompatible changes in 2.2
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=====================================
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Database backend API
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--------------------
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* Third-party database backends must implement support for table check
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constraints or set ``DatabaseFeatures.supports_table_check_constraints`` to
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``False``.
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* Third party database backends must implement support for ignoring
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constraints or uniqueness errors while inserting or set
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``DatabaseFeatures.supports_ignore_conflicts`` to ``False``.
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:mod:`django.contrib.gis`
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-------------------------
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* Support for GDAL 1.9 and 1.10 is dropped.
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Miscellaneous
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-------------
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* To improve readability, the ``UUIDField`` form field now displays values with
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dashes, e.g. ``550e8400-e29b-41d4-a716-446655440000`` instead of
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``550e8400e29b41d4a716446655440000``.
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* On SQLite, ``PositiveIntegerField`` and ``PositiveSmallIntegerField`` now
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include a check constraint to prevent negative values in the database. If you
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have existing invalid data and run a migration that recreates a table, you'll
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see ``CHECK constraint failed``.
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* For consistency with WSGI servers, the test client now sets the
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``Content-Length`` header to a string rather than an integer.
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* The return value of :func:`django.utils.text.slugify` is no longer marked as
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HTML safe.
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* The default truncation character used by the :tfilter:`urlizetrunc`,
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:tfilter:`truncatechars`, :tfilter:`truncatechars_html`,
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:tfilter:`truncatewords`, and :tfilter:`truncatewords_html` template filters
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is now the real ellipsis character (``…``) instead of 3 dots. You may have to
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adapt some test output comparisons.
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* Support for bytestring paths in the template filesystem loader is removed.
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* :func:`django.utils.http.urlsafe_base64_encode` now returns a string instead
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of a bytestring, and :func:`django.utils.http.urlsafe_base64_decode` may no
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longer be passed a bytestring.
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* Support for ``cx_Oracle`` < 6.0 is removed.
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|
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.. _deprecated-features-2.2:
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Features deprecated in 2.2
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==========================
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Model ``Meta.ordering`` will no longer affect ``GROUP BY`` queries
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------------------------------------------------------------------
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A model's ``Meta.ordering`` affecting ``GROUP BY`` queries (such as
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``.annotate().values()``) is a common source of confusion. Such queries now
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issue a deprecation warning with the advice to add an ``order_by()`` to retain
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the current query. ``Meta.ordering`` will be ignored in such queries starting
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in Django 3.1.
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Miscellaneous
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-------------
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* ``django.utils.timezone.FixedOffset`` is deprecated in favor of
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:class:`datetime.timezone`.
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* The undocumented ``QuerySetPaginator`` alias of
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``django.core.paginator.Paginator`` is deprecated.
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* The ``FloatRangeField`` model and form fields in ``django.contrib.postgres``
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are deprecated in favor of a new name, ``DecimalRangeField``, to match the
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underlying ``numrange`` data type used in the database.
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* The ``FILE_CHARSET`` setting is deprecated. Starting with Django 3.1, files
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read from disk must be UTF-8 encoded.
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