Update django to 2.1.7

[pyup-bot]

This PR updates django from 1.9.9 to 2.1.7.

Changelog

2.1.7

==========================

*February 11, 2019*

Django 2.1.7 fixes a packaging error in 2.1.6.

Bugfixes
========

* Corrected packaging error from 2.1.6 (:ticket:`30175`).


==========================

2.1.6

==========================

*February 11, 2019*

Django 2.1.6 fixes a security issue and a bug in 2.1.5.

CVE-2019-6975: Memory exhaustion in ``django.utils.numberformat.format()``
--------------------------------------------------------------------------

If ``django.utils.numberformat.format()`` -- used by ``contrib.admin`` as well
as the the ``floatformat``, ``filesizeformat``, and ``intcomma`` templates
filters -- received a ``Decimal`` with a large number of digits or a large
exponent, it could lead to significant memory usage due to a call to
``'{:f}'.format()``.

To avoid this, decimals with more than 200 digits are now formatted using
scientific notation.

Bugfixes
========

* Made the ``obj`` argument of ``InlineModelAdmin.has_add_permission()``
optional to restore backwards compatibility with third-party code that
doesn't provide it (:ticket:`30097`).


==========================

2.1.5

==========================

*January 4, 2019*

Django 2.1.5 fixes a security issue and several bugs in 2.1.4.

CVE-2019-3498: Content spoofing possibility in the default 404 page
-------------------------------------------------------------------

An attacker could craft a malicious URL that could make spoofed content appear
on the default page generated by the ``django.views.defaults.page_not_found()``
view.

The URL path is no longer displayed in the default 404 template and the
``request_path`` context variable is now quoted to fix the issue for custom
templates that use the path.

Bugfixes
========

* Fixed compatibility with mysqlclient 1.3.14 (:ticket:`30013`).

* Fixed a schema corruption issue on SQLite 3.26+. You might have to drop and
rebuild your SQLite database if you applied a migration while using an older
version of Django with SQLite 3.26 or later (:ticket:`29182`).

* Prevented SQLite schema alterations while foreign key checks are enabled to
avoid the possibility of schema corruption (:ticket:`30023`).

* Fixed a regression in Django 2.1.4 (which enabled keep-alive connections)
where request body data isn't properly consumed for such connections
(:ticket:`30015`).

* Fixed a regression in Django 2.1.4 where
``InlineModelAdmin.has_change_permission()`` is incorrectly called with a
non-``None`` ``obj`` argument during an object add (:ticket:`30050`).


==========================

2.1.4

==========================

*December 3, 2018*

Django 2.1.4 fixes several bugs in 2.1.3.

Bugfixes
========

* Corrected the default password list that ``CommonPasswordValidator`` uses by
lowercasing all passwords to match the format expected by the validator
(:ticket:`29952`).

* Prevented repetitive calls to ``geos_version_tuple()`` in the ``WKBWriter``
class in an attempt to fix a random crash involving ``LooseVersion``
(:ticket:`29959`).

* Fixed keep-alive support in ``runserver`` after it was disabled to fix
another issue in Django 2.0 (:ticket:`29849`).

* Fixed admin view-only change form crash when using
``ModelAdmin.prepopulated_fields`` (:ticket:`29929`).

* Fixed "Please correct the errors below" error message when editing an object
in the admin if the user only has the "view" permission on inlines
(:ticket:`29930`).


==========================

2.1.3

==========================

*November 1, 2018*

Django 2.1.3 fixes several bugs in 2.1.2.

Bugfixes
========

* Fixed a regression in Django 2.0 where combining ``Q`` objects with ``__in``
lookups and lists crashed (:ticket:`29838`).

* Fixed a regression in Django 1.11 where ``django-admin shell`` may hang
on startup (:ticket:`29774`).

* Fixed a regression in Django 2.0 where test databases aren't reused with
``manage.py test --keepdb`` on MySQL (:ticket:`29827`).

* Fixed a regression where cached foreign keys that use ``to_field`` were
incorrectly cleared in ``Model.save()`` (:ticket:`29896`).

* Fixed a regression in Django 2.0 where ``FileSystemStorage`` crashes with
``FileExistsError`` if concurrent saves try to create the same directory
(:ticket:`29890`).


==========================

2.1.2

==========================

*October 1, 2018*

Django 2.1.2 fixes a security issue and several bugs in 2.1.1. Also, the latest
string translations from Transifex are incorporated.

CVE-2018-16984: Password hash disclosure to "view only" admin users
===================================================================

If an admin user has the change permission to the user model, only part of the
password hash is displayed in the change form. Admin users with the view (but
not change) permission to the user model were displayed the entire hash. While
it's typically infeasible to reverse a strong password hash, if your site uses
weaker password hashing algorithms such as MD5 or SHA1, it could be a problem.

Bugfixes
========

* Fixed a regression where nonexistent joins in ``F()`` no longer raised
``FieldError`` (:ticket:`29727`).

* Fixed a regression where files starting with a tilde or underscore weren't
ignored by the migrations loader (:ticket:`29749`).

* Made migrations detect changes to ``Meta.default_related_name``
(:ticket:`29755`).

* Added compatibility for ``cx_Oracle`` 7 (:ticket:`29759`).

* Fixed a regression in Django 2.0 where unique index names weren't quoted
(:ticket:`29778`).

* Fixed a regression where sliced queries with multiple columns with the same
name crashed on Oracle 12.1 (:ticket:`29630`).

* Fixed a crash when a user with the view (but not change) permission made a
POST request to an admin user change form (:ticket:`29809`).


==========================

2.1.1

==========================

*August 31, 2018*

Django 2.1.1 fixes several bugs in 2.1.

Bugfixes
========

* Fixed a race condition in ``QuerySet.update_or_create()`` that could result
in data loss (:ticket:`29499`).

* Fixed a regression where ``QueryDict.urlencode()`` crashed if the dictionary
contains a non-string value (:ticket:`29627`).

* Fixed a regression in Django 2.0 where using ``manage.py test --keepdb``
fails on PostgreSQL if the database exists and the user doesn't have
permission to create databases (:ticket:`29613`).

* Fixed a regression in Django 2.0 where combining ``Q`` objects with ``__in``
lookups and lists crashed (:ticket:`29643`).

* Fixed translation failure of ``DurationField``'s "overflow" error message
(:ticket:`29623`).

* Fixed a regression where the admin change form crashed if the user doesn't
have the 'add' permission to a model that uses ``TabularInline``
(:ticket:`29637`).

* Fixed a regression where a ``related_query_name`` reverse accessor wasn't set
up when a ``GenericRelation`` is declared on an abstract base model
(:ticket:`29653`).

* Fixed the test client's JSON serialization of a request data dictionary for
structured content type suffixes (:ticket:`29662`).

* Made the admin change view redirect to the changelist view after a POST if
the user has the 'view' permission (:ticket:`29663`).

* Fixed admin change view crash for view-only users if the form has an extra
form field (:ticket:`29682`).

* Fixed a regression in Django 2.0.5 where ``QuerySet.values()`` or
``values_list()`` after combining querysets with ``extra()`` with
``union()``, ``difference()``, or ``intersection()`` crashed due to
mismatching columns (:ticket:`29694`).

* Fixed crash if ``InlineModelAdmin.has_add_permission()`` doesn't accept the
``obj`` argument (:ticket:`29723`).


========================

2.1

========================

*August 1, 2018*

Welcome to Django 2.1!

These release notes cover the :ref:`new features <whats-new-2.1>`, as well as
some :ref:`backwards incompatible changes <backwards-incompatible-2.1>` you'll
want to be aware of when upgrading from Django 2.0 or earlier. We've
:ref:`dropped some features<removed-features-2.1>` that have reached the end of
their deprecation cycle, and we've :ref:`begun the deprecation process for some
features <deprecated-features-2.1>`.

See the :doc:`/howto/upgrade-version` guide if you're updating an existing
project.

Python compatibility
====================

Django 2.1 supports Python 3.5, 3.6, and 3.7. Django 2.0 is the last version to
support Python 3.4.  We **highly recommend** and only officially support the
latest release of each series.

.. _whats-new-2.1:

What's new in Django 2.1
========================

Model "view" permission
-----------------------

A "view" permission is added to the model :attr:`Meta.default_permissions
<django.db.models.Options.default_permissions>`. The new permissions will be
created automatically when running :djadmin:`migrate`.

This allows giving users read-only access to models in the admin.
:meth:`.ModelAdmin.has_view_permission` is new. The implementation is backwards
compatible in that there isn't a need to assign the "view" permission to allow
users who have the "change" permission to edit objects.

There are a couple of :ref:`backwards incompatible considerations
<view_permission_backwards_incompatible>`.

Minor features
--------------

:mod:`django.contrib.admin`
~~~~~~~~~~~~~~~~~~~~~~~~~~~

* :attr:`.ModelAdmin.search_fields` now accepts any lookup such as
``field__exact``.

* jQuery is upgraded from version 2.2.3 to 3.3.1.

* The new :meth:`.ModelAdmin.delete_queryset` method allows customizing the
deletion process of the "delete selected objects" action.

* You can now :ref:`override the default admin site
<overriding-default-admin-site>`.

* The new :attr:`.ModelAdmin.sortable_by` attribute and
:meth:`.ModelAdmin.get_sortable_by` method allow limiting the columns that
can be sorted in the change list page.

* The ``admin_order_field`` attribute for elements in
:attr:`.ModelAdmin.list_display` may now be a query expression.

* The new :meth:`.ModelAdmin.get_deleted_objects()` method allows customizing
the deletion process of the delete view and the "delete selected" action.

* The ``actions.html``, ``change_list_results.html``, ``date_hierarchy.html``,
``pagination.html``, ``prepopulated_fields_js.html``, ``search_form.html``,
and ``submit_line.html`` templates can now be :ref:`overridden per app or
per model <admin-templates-overridden-per-app-or-model>` (besides overridden
globally).

* The admin change list and change form object tools can now be :ref:`overridden
per app, per model, or globally <admin-templates-overridden-per-app-or-model>`
with ``change_list_object_tools.html`` and
``change_form_object_tools.html`` templates.

* :meth:`.InlineModelAdmin.has_add_permission` is now passed the parent object
as the second positional argument, ``obj``.

* Admin actions may now :ref:`specify permissions <admin-action-permissions>`
to limit their availability to certain users.

:mod:`django.contrib.auth`
~~~~~~~~~~~~~~~~~~~~~~~~~~

* :djadmin:`createsuperuser` now gives a prompt to allow bypassing the
:setting:`AUTH_PASSWORD_VALIDATORS` checks.

:mod:`django.contrib.gis`
~~~~~~~~~~~~~~~~~~~~~~~~~

* The new :meth:`.GEOSGeometry.buffer_with_style` method is a version of
:meth:`~.GEOSGeometry.buffer` that allows customizing the style of the
buffer.

* :class:`~django.contrib.gis.forms.widgets.OpenLayersWidget` is now based on
OpenLayers 4.6.5 (previously 3.20.1).

:mod:`django.contrib.sessions`
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

* Added the :setting:`SESSION_COOKIE_SAMESITE` setting to set the ``SameSite``
cookie flag on session cookies.

Cache
~~~~~

* The :ref:`local-memory cache backend <local-memory-caching>` now uses a
least-recently-used (LRU) culling strategy rather than a pseudo-random one.

* The new :meth:`~django.core.caches.cache.touch` method of the :ref:`low-level
cache API <low-level-cache-api>` updates the timeout of cache keys.

CSRF
~~~~

* Added the :setting:`CSRF_COOKIE_SAMESITE` setting to set the ``SameSite``
cookie flag on CSRF cookies.

Forms
~~~~~

* The widget for ``ImageField`` now renders with the HTML attribute
``accept="image/*"``.

Internationalization
~~~~~~~~~~~~~~~~~~~~

* Added the :meth:`~django.utils.translation.get_supported_language_variant`
function.

* Untranslated strings for territorial language variants now use the
translations of the generic language. For example, untranslated ``pt_BR``
strings use ``pt`` translations.

Management Commands
~~~~~~~~~~~~~~~~~~~

* The new :option:`inspectdb --include-views` option allows creating models
for database views.

* The :class:`~django.core.management.BaseCommand` class now uses a custom help
formatter so that the standard options like ``--verbosity`` or ``--settings``
appear last in the help output, giving a more prominent position to subclassed
command's options.

Migrations
~~~~~~~~~~

* Added support for serialization of ``functools.partialmethod`` objects.

* To support frozen environments, migrations may be loaded from ``.pyc`` files.

Models
~~~~~~

* Models can now use ``__init_subclass__()`` from :pep:`487`.

* A ``BinaryField`` may now be set to ``editable=True`` if you wish to include
it in model forms.

* A number of new text database functions are added:
:class:`~django.db.models.functions.Chr`,
:class:`~django.db.models.functions.Left`,
:class:`~django.db.models.functions.LPad`,
:class:`~django.db.models.functions.LTrim`,
:class:`~django.db.models.functions.Ord`,
:class:`~django.db.models.functions.Repeat`,
:class:`~django.db.models.functions.Replace`,
:class:`~django.db.models.functions.Right`,
:class:`~django.db.models.functions.RPad`,
:class:`~django.db.models.functions.RTrim`, and
:class:`~django.db.models.functions.Trim`.

* The new :class:`~django.db.models.functions.TruncWeek` function truncates
:class:`~django.db.models.DateField` and
:class:`~django.db.models.DateTimeField` to the Monday of a week.

* Query expressions can now be negated using a minus sign.

* :meth:`.QuerySet.order_by` and :meth:`distinct(*fields) <.QuerySet.distinct>`
now support using field transforms.

* :class:`~django.db.models.BooleanField` can now be ``null=True``. This is
encouraged instead of :class:`~django.db.models.NullBooleanField`, which will
likely be deprecated in the future.

* The new :meth:`.QuerySet.explain` method displays the database's execution
plan of a queryset's query.

*  :meth:`.QuerySet.raw` now supports :meth:`~.QuerySet.prefetch_related`.

Requests and Responses
~~~~~~~~~~~~~~~~~~~~~~

* Added :meth:`.HttpRequest.get_full_path_info`.

* Added the ``samesite`` argument to :meth:`.HttpResponse.set_cookie` to allow
setting the ``SameSite`` cookie flag.

* The new ``as_attachment`` argument for :class:`~django.http.FileResponse`
sets the ``Content-Disposition`` header to make the browser ask if the user
wants to download the file. ``FileResponse`` also tries to set the
``Content-Type`` and ``Content-Length`` headers where appropriate.

Templates
~~~~~~~~~

* The new :tfilter:`json_script` filter safely outputs a Python object as JSON,
wrapped in a ``<script>`` tag, ready for use with JavaScript.

Tests
~~~~~

* Added test :class:`~django.test.Client` support for 307 and 308 redirects.

* The test :class:`~django.test.Client` now serializes a request data
dictionary as JSON if ``content_type='application/json'``. You can customize
the JSON encoder with test client's ``json_encoder`` parameter.

* The new :meth:`.SimpleTestCase.assertWarnsMessage` method is a simpler
version of :meth:`~unittest.TestCase.assertWarnsRegex`.

.. _backwards-incompatible-2.1:

Backwards incompatible changes in 2.1
=====================================

Database backend API
--------------------

This section describes changes that may be needed in third-party database
backends.

* To adhere to :pep:`249`, exceptions where a database doesn't support a
feature are changed from :exc:`NotImplementedError` to
:exc:`django.db.NotSupportedError`.

* Renamed the ``allow_sliced_subqueries`` database feature flag to
``allow_sliced_subqueries_with_in``.

* ``DatabaseOperations.distinct_sql()`` now requires an additional ``params``
argument and returns a tuple of SQL and parameters instead of a SQL string.

* ``DatabaseFeatures.introspected_boolean_field_type`` is changed from a method
to a property.

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

* Support for SpatiaLite 4.0 is removed.

Dropped support for MySQL 5.5
-----------------------------

The end of upstream support for MySQL 5.5 is December 2018. Django 2.1 supports
MySQL 5.6 and higher.

Dropped support for PostgreSQL 9.3
----------------------------------

The end of upstream support for PostgreSQL 9.3 is September 2018. Django 2.1
supports PostgreSQL 9.4 and higher.

Removed ``BCryptPasswordHasher`` from the default ``PASSWORD_HASHERS`` setting
------------------------------------------------------------------------------

If you used bcrypt with Django 1.4 or 1.5 (before ``BCryptSHA256PasswordHasher``
was added in Django 1.6), you might have some passwords that use the
``BCryptPasswordHasher`` hasher.

You can check if that's the case like this::

 from django.contrib.auth import get_user_model
 User = get_user_model()
 User.objects.filter(password__startswith='bcrypt$$')

If you want to continue to allow those passwords to be used, you'll
have to define the :setting:`PASSWORD_HASHERS` setting (if you don't already)
and include ``'django.contrib.auth.hashers.BCryptPasswordHasher'``.

Moved ``wrap_label`` widget template context variable
-----------------------------------------------------

To fix the lack of ``<label>`` when using ``RadioSelect`` and
``CheckboxSelectMultiple`` with ``MultiWidget``, the ``wrap_label`` context
variable now appears as an attribute of each option. For example, in a custom
``input_option.html`` template, change ``{% if wrap_label %}`` to
``{% if widget.wrap_label %}``.

``SameSite`` cookies
--------------------

The cookies used for ``django.contrib.sessions``, ``django.contrib.messages``,
and Django's CSRF protection now set the ``SameSite`` flag to ``Lax`` by
default. Browsers that respect this flag won't send these cookies on
cross-origin requests. If you rely on the old behavior, set the
:setting:`SESSION_COOKIE_SAMESITE` and/or :setting:`CSRF_COOKIE_SAMESITE`
setting to ``None``.

.. _view_permission_backwards_incompatible:

Considerations for the new model "view" permission
--------------------------------------------------

Custom admin forms need to take the view-only case into account
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

With the new "view" permission, existing custom admin forms may raise errors
when a user doesn't have the change permission because the form might access
nonexistent fields. Fix this by overriding :meth:`.ModelAdmin.get_form` and
checking if the user has the "change" permissions and returning the default
form if not::

 class MyAdmin(admin.ModelAdmin):
     def get_form(self, request, obj=None, **kwargs):
         if not self.has_change_permission(request, obj):
             return super().get_form(request, obj, **kwargs)
         return CustomForm

New default view permission could allow unwanted access to admin views
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

If you have a custom permission with a codename of the form
``view_<modelname>``, the new view permission handling in the admin will allow
view access to the changelist and detail pages for those models. If this is
unwanted, you must change your custom permission codename.

Miscellaneous
-------------

* The minimum supported version of ``mysqlclient`` is increased from 1.3.3 to
1.3.7.

* Support for SQLite < 3.7.15 is removed.

* The date format of ``Set-Cookie``'s ``Expires`` directive is changed to
follow :rfc:`7231section-7.1.1.1` instead of Netscape's cookie standard.
Hyphens present in dates like ``Tue, 25-Dec-2018 22:26:13 GMT`` are removed.
This change should be merely cosmetic except perhaps for antiquated browsers
that don't parse the new format.

* ``allowed_hosts`` is now a required argument of private API
``django.utils.http.is_safe_url()``.

* The ``multiple`` attribute rendered by the
:class:`~django.forms.SelectMultiple` widget now uses HTML5 boolean syntax
rather than XHTML's ``multiple="multiple"``.

* HTML rendered by form widgets no longer includes a closing slash on void
elements, e.g. ``<br>``. This is incompatible within XHTML, although some
widgets already used aspects of HTML5 such as boolean attributes.

* The value of :class:`~django.forms.SelectDateWidget`'s empty options is
changed from 0 to an empty string, which mainly may require some adjustments
in tests that compare HTML.

* :meth:`.User.has_usable_password` and the
:func:`~django.contrib.auth.hashers.is_password_usable` function no longer
return ``False`` if the password is ``None`` or an empty string, or if the
password uses a hasher that's not in the :setting:`PASSWORD_HASHERS` setting.
This undocumented behavior was a regression in Django 1.6 and prevented users
with such passwords from requesting a password reset. Audit your code to
confirm that your usage of these APIs don't rely on the old behavior.

* Since migrations are now loaded from ``.pyc`` files, you might need to delete
them if you're working in a mixed Python 2 and Python 3 environment.

* Using ``None`` as a :class:`~django.contrib.postgres.fields.JSONField` lookup
value now matches objects that have the specified key and a null value rather
than objects that don't have the key.

* The admin CSS class ``field-box`` is renamed to ``fieldBox`` to prevent
conflicts with the class given to model fields named "box".

* Since the admin's ``actions.html``, ``change_list_results.html``,
``date_hierarchy.html``, ``pagination.html``, ``prepopulated_fields_js.html``,
``search_form.html``, and ``submit_line.html`` templates can now be
overridden per app or per model, you may need to rename existing templates
with those names that were written for a different purpose.

* ``QuerySet.raw()`` now caches its results like regular querysets. Use
``iterator()`` if you don't want caching.

* The database router :meth:`allow_relation` method is called in more cases.
Improperly written routers may need to be updated accordingly.

* Translations are no longer deactivated before running management commands.
If your custom command requires translations to be deactivated (for example,
to insert untranslated content into the database), use the new
:ref:`no_translations decorator <management-commands-and-locales>`.

* Management commands no longer allow the abbreviated forms of the
``--settings`` and ``--pythonpath`` arguments.

* The private ``django.db.models.sql.constants.QUERY_TERMS`` constant is
removed. The :meth:`~.RegisterLookupMixin.get_lookup`
and :meth:`~.RegisterLookupMixin.get_lookups` methods
of the :ref:`Lookup Registration API <lookup-registration-api>` may be
suitable alternatives. Compared to the ``QUERY_TERMS`` constant, they allow
your code to also account for any custom lookups that have been registered.

* Compatibility with ``py-bcrypt`` is removed as it's unmaintained. Use `bcrypt
<https://pypi.org/project/bcrypt/>`_ instead.

.. _deprecated-features-2.1:

Features deprecated in 2.1
==========================

Miscellaneous
-------------

* The ``ForceRHR`` GIS function is deprecated in favor of the new
:class:`~django.contrib.gis.db.models.functions.ForcePolygonCW` function.

* ``django.utils.http.cookie_date()`` is deprecated in favor of
:func:`~django.utils.http.http_date`, which follows the format of the latest
RFC.

* ``{% load staticfiles %}`` and ``{% load admin_static %}`` are deprecated
in favor of ``{% load static %}``, which works the same.

* ``django.contrib.staticfiles.templatetags.static()`` is deprecated in favor
of ``django.templatetags.static.static()``.

* Support for :meth:`.InlineModelAdmin.has_add_permission` methods that don't
accept ``obj`` as the second positional argument will be removed in Django
3.0.

.. _removed-features-2.1:

Features removed in 2.1
=======================

These features have reached the end of their deprecation cycle and are removed
in Django 2.1. See :ref:`deprecated-features-1.11` for details, including how
to remove usage of these features.

* ``contrib.auth.views.login()``, ``logout()``, ``password_change()``,
``password_change_done()``, ``password_reset()``, ``password_reset_done()``,
``password_reset_confirm()``, and ``password_reset_complete()`` are removed.

* The ``extra_context`` parameter of ``contrib.auth.views.logout_then_login()``
is removed.

* ``django.test.runner.setup_databases()`` is removed.

* ``django.utils.translation.string_concat()`` is removed.

* ``django.core.cache.backends.memcached.PyLibMCCache`` no longer supports
passing ``pylibmc`` behavior settings as top-level attributes of ``OPTIONS``.

* The ``host`` parameter of ``django.utils.http.is_safe_url()`` is removed.

* Silencing of exceptions raised while rendering the ``{% include %}`` template
tag is removed.

* ``DatabaseIntrospection.get_indexes()`` is removed.

* The ``authenticate()`` method of authentication backends requires ``request``
as the first positional argument.

* The ``django.db.models.permalink()`` decorator is removed.

* The ``USE_ETAGS`` setting is removed. ``CommonMiddleware`` and
``django.utils.cache.patch_response_headers()`` no longer set ETags.

* The ``Model._meta.has_auto_field`` attribute is removed.

* ``url()``'s support for inline flags in regular expression groups (``(?i)``,
``(?L)``, ``(?m)``, ``(?s)``, and ``(?u)``) is removed.

* Support for ``Widget.render()`` methods without the ``renderer`` argument
is removed.


===========================

2.0.12

===========================

*February 11, 2019*

Django 2.0.12 fixes a packaging error in 2.0.11.

Bugfixes
========

* Corrected packaging error from 2.0.11 (:ticket:`30175`).


===========================

2.0.11

===========================

*February 11, 2019*

Django 2.0.11 fixes a security issue in 2.0.10.

CVE-2019-6975: Memory exhaustion in ``django.utils.numberformat.format()``
--------------------------------------------------------------------------

If ``django.utils.numberformat.format()`` -- used by ``contrib.admin`` as well
as the the ``floatformat``, ``filesizeformat``, and ``intcomma`` templates
filters -- received a ``Decimal`` with a large number of digits or a large
exponent, it could lead to significant memory usage due to a call to
``'{:f}'.format()``.

To avoid this, decimals with more than 200 digits are now formatted using
scientific notation.


===========================

2.0.10

===========================

*January 4, 2019*

Django 2.0.10 fixes a security issue and several bugs in 2.0.9.

CVE-2019-3498: Content spoofing possibility in the default 404 page
-------------------------------------------------------------------

An attacker could craft a malicious URL that could make spoofed content appear
on the default page generated by the ``django.views.defaults.page_not_found()``
view.

The URL path is no longer displayed in the default 404 template and the
``request_path`` context variable is now quoted to fix the issue for custom
templates that use the path.

Bugfixes
========

* Prevented repetitive calls to ``geos_version_tuple()`` in the ``WKBWriter``
class in an attempt to fix a random crash involving ``LooseVersion`` since
Django 2.0.6 (:ticket:`29959`).

* Fixed a schema corruption issue on SQLite 3.26+. You might have to drop and
rebuild your SQLite database if you applied a migration while using an older
version of Django with SQLite 3.26 or later (:ticket:`29182`).

* Prevented SQLite schema alterations while foreign key checks are enabled to
avoid the possibility of schema corruption (:ticket:`30023`).


==========================

2.0.9

==========================

*October 1, 2018*

Django 2.0.9 fixes a data loss bug in 2.0.8.

Bugfixes
========

* Fixed a race condition in ``QuerySet.update_or_create()`` that could result
in data loss (:ticket:`29499`).


==========================

2.0.8

==========================

*August 1, 2018*

Django 2.0.8 fixes a security issue and several bugs in 2.0.7.

CVE-2018-14574: Open redirect possibility in ``CommonMiddleware``
=================================================================

If the :class:`~django.middleware.common.CommonMiddleware` and the
:setting:`APPEND_SLASH` setting are both enabled, and if the project has a
URL pattern that accepts any path ending in a slash (many content management
systems have such a pattern), then a request to a maliciously crafted URL of
that site could lead to a redirect to another site, enabling phishing and other
attacks.

``CommonMiddleware`` now escapes leading slashes to prevent redirects to other
domains.

Bugfixes
========

* Fixed a regression in Django 2.0.7 that broke the ``regex`` lookup on MariaDB
(even though MariaDB isn't officially supported) (:ticket:`29544`).

* Fixed a regression where ``django.template.Template`` crashed if the
``template_string`` argument is lazy (:ticket:`29617`).


==========================

2.0.7

==========================

*July 2, 2018*

Django 2.0.7 fixes several bugs in 2.0.6.

Bugfixes
========

* Fixed admin changelist crash when using a query expression without ``asc()``
or ``desc()`` in the page's ordering (:ticket:`29428`).

* Fixed admin check crash when using a query expression in
``ModelAdmin.ordering`` (:ticket:`29428`).

* Fixed ``__regex`` and ``__iregex`` lookups with MySQL 8 (:ticket:`29451`).

* Fixed migrations crash with namespace packages on Python 3.7
(:ticket:`28814`).


==========================

2.0.6

==========================

*June 1, 2018*

Django 2.0.6 fixes several bugs in 2.0.5.

Bugfixes
========

* Fixed a regression that broke custom template filters that use decorators
(:ticket:`29400`).

* Fixed detection of custom URL converters in included patterns
(:ticket:`29415`).

* Fixed a regression that added an unnecessary subquery to the ``GROUP BY``
clause on MySQL when using a ``RawSQL`` annotation (:ticket:`29416`).

* Fixed ``WKBWriter.write()`` and ``write_hex()`` for empty polygons on
GEOS 3.6.1+ (:ticket:`29460`).

* Fixed a regression in Django 1.10 that could result in large memory usage
when making edits using ``ModelAdmin.list_editable`` (:ticket:`28462`).


==========================

2.0.5

==========================

*May 1, 2018*

Django 2.0.5 fixes several bugs in 2.0.4.

Bugfixes
========

* Corrected the import paths that ``inspectdb`` generates for
``django.contrib.postgres`` fields (:ticket:`29307`).

* Fixed a regression in Django 1.11.8 where altering a field with a unique
constraint may drop and rebuild more foreign keys than necessary
(:ticket:`29193`).

* Fixed crashes in ``django.contrib.admindocs`` when a view is a callable
object, such as ``django.contrib.syndication.views.Feed`` (:ticket:`29296`).

* Fixed a regression in Django 2.0.4 where ``QuerySet.values()`` or
``values_list()`` after combining an annotated and unannotated queryset with
``union()``, ``difference()``, or ``intersection()`` crashed due to mismatching
columns (:ticket:`29286`).


==========================

2.0.4

==========================

*April 2, 2018*

Django 2.0.4 fixes several bugs in 2.0.3.

Bugfixes
========

* Fixed a crash when filtering with an ``Exists()`` annotation of a queryset
containing a single field (:ticket:`29195`).

* Fixed admin autocomplete widget's translations for `zh-hans` and `zh-hant`
languages (:ticket:`29213`).

* Corrected admin's autocomplete widget to add a space after custom classes
(:ticket:`29221`).

* Fixed ``PasswordResetConfirmView`` crash when using a user model with a
``UUIDField`` primary key and the reset URL contains an encoded primary key
value that decodes to an invalid UUID (:ticket:`29206`).

* Fixed a regression in Django 1.11.8 where combining two annotated
``values_list()`` querysets with ``union()``, ``difference()``, or
``intersection()`` crashed due to mismatching columns (:ticket:`29229`).

* Fixed a regression in Django 1.11 where an empty choice could be initially
selected for the ``SelectMultiple`` and ``CheckboxSelectMultiple`` widgets
(:ticket:`29273`).

* Fixed a regression in Django 2.0 where ``OpenLayersWidget`` deserialization
ignored the widget map's SRID and assumed 4326 (WGS84) (:ticket:`29116`).


==========================

2.0.3

==========================

*March 6, 2018*

Django 2.0.3 fixes two security issues and several bugs in 2.0.2. Also, the
latest string translations from Transifex are incorporated.

CVE-2018-7536: Denial-of-service possibility in ``urlize`` and ``urlizetrunc`` template filters
===============================================================================================

The ``django.utils.html.urlize()`` function was extremely slow to evaluate
certain inputs due to catastrophic backtracking vulnerabilities in two regular
expressions. The ``urlize()`` function is used to implement the ``urlize`` and
``urlizetrunc`` template filters, which were thus vulnerable.

The problematic regular expressions are replaced with parsing logic that
behaves similarly.

CVE-2018-7537: Denial-of-service possibility in ``truncatechars_html`` and ``truncatewords_html`` template filters
==================================================================================================================

If ``django.utils.text.Truncator``'s ``chars()`` and ``words()`` methods were
passed the ``html=True`` argument, they were extremely slow to evaluate certain
inputs due to a catastrophic backtracking vulnerability in a regular
expression. The ``chars()`` and ``words()`` methods are used to implement the
``truncatechars_html`` and ``truncatewords_html`` template filters, which were
thus vulnerable.

The backtracking problem in the regular expression is fixed.

Bugfixes
========

* Fixed a regression that caused sliced ``QuerySet.distinct().order_by()``
followed by ``count()`` to crash (:ticket:`29108`).

* Prioritized the datetime and time input formats without ``%f`` for the Thai
locale to fix the admin time picker widget displaying "undefined"
(:ticket:`29109`).

* Fixed crash with ``QuerySet.order_by(Exists(...))`` (:ticket:`29118`).

* Made ``Q.deconstruct()`` deterministic with multiple keyword arguments
(:ticket:`29125`). You may need to modify ``Q``'s in existing migrations, or
accept an autogenerated migration.

* Fixed a regression where a ``When()`` expression with a list argument crashes
(:ticket:`29166`).

* Fixed crash when using a ``Window()`` expression in a subquery
(:ticket:`29172`).

* Fixed ``AbstractBaseUser.normalize_username()`` crash if the ``username``
argument isn't a string (:ticket:`29176`).


==========================

2.0.2

==========================

*February 1, 2018*

Django 2.0.2 fixes a security issue and several bugs in 2.0.1.

CVE-2018-6188: Information leakage in ``AuthenticationForm``
============================================================

A regression in Django 1.11.8 made
:class:`~django.contrib.auth.forms.AuthenticationForm` run its
``confirm_login_allowed()`` method even if an incorrect password is entered.
This can leak information about a user, depending on what messages
``confirm_login_allowed()`` raises. If ``confirm_login_allowed()`` isn't
overridden, an attacker enter an arbitrary username and see if that user has
been set to ``is_active=False``. If ``confirm_login_allowed()`` is overridden,
more sensitive details could be leaked.

This issue is fixed with the caveat that ``AuthenticationForm`` can no longer
raise the "This account is inactive." error if the authentication backend
rejects inactive users (the default authentication backend, ``ModelBackend``,
has done that since Django 1.10). This issue will be revisited for Django 2.1
as a fix to address the caveat will likely be too invasive for inclusion in
older versions.

Bugfixes
========

* Fixed hidden content at the bottom of the "The install worked successfully!"
page for some languages (:ticket:`28885`).

* Fixed incorrect foreign key nullification if a model has two foreign keys to
the same model and a target model is deleted (:ticket:`29016`).

* Fixed regression in the use of ``QuerySet.values_list(..., flat=True)``
followed by ``annotate()`` (:ticket:`29067`).

* Fixed a regression where a queryset that annotates with geometry objects
crashes (:ticket:`29054`).

* Fixed a regression where ``contrib.auth.authenticate()`` crashes if an
authentication backend doesn't accept ``request`` and a later one does
(:ticket:`29071`).

* Fixed a regression where ``makemigrations`` crashes if a migrations directory
doesn't have an ``__init__.py`` file (:ticket:`29091`).

* Fixed crash when entering an invalid uuid in ``ModelAdmin.raw_id_fields``
(:ticket:`29094`).


==========================

2.0.1

==========================

*January 1, 2018*

Django 2.0.1 fixes several bugs in 2.0.

Bugfixes
========

* Fixed a regression in Django 1.11 that added newlines between ``MultiWidget``'s
subwidgets (:ticket:`28890`).

* Fixed incorrect class-based model index name generation for models with
quoted ``db_table`` (:ticket:`28876`).

* Fixed incorrect foreign key constraint name for models with quoted
``db_table`` (:ticket:`28876`).

* Fixed a regression in caching of a ``GenericForeignKey`` when the referenced
model instance uses more than one level of multi-table inheritance
(:ticket:`28856`).

* Reallowed filtering a queryset with ``GeometryField=None`` (:ticket:`28896`).

* Corrected admin check to allow a ``OneToOneField`` in
``ModelAdmin.autocomplete_fields`` (:ticket:`28898`).

* Fixed a regression on SQLite where ``DecimalField`` returned a result with
trailing zeros in the fractional part truncated (:ticket:`28915`).

* Fixed crash in the ``testserver`` command startup (:ticket:`28941`).

* Fixed crash when coercing a translatable URL pattern to ``str``
(:ticket:`28947`).

* Fixed crash on SQLite when renaming a field in a model referenced by a
``ManyToManyField`` (:ticket:`28884`).

* Fixed a crash when chaining ``values()`` or ``values_list()`` after
``QuerySet.select_for_update(of=(...))`` (:ticket:`28944`).

* Fixed admin changelist crash when using a query expression in the page's
ordering (:ticket:`28958`).


========================

2.0

========================

*December 2, 2017*

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>`.

This release starts Django's use of a :ref:`loose form of semantic versioning
<internal-release-cadence>`, but there aren't any major backwards incompatible
changes that might be expected of a 2.0 release. Upgrading should be a similar
amount of effort as past feature releases.

See the :doc:`/howto/upgrade-version` guide if you're updating an existing
project.

Python compatibility
====================

Django 2.0 supports Python 3.4, 3.5, 3.6, and 3.7. We **highly recommend** and
only officially support the latest release of each series.

The Django 1.11.x series is the last to support Python 2.7.

Django 2.0 will be the last release series to support Python 3.4. If you plan
a deployment of Python 3.4 beyond the end-of-life for Django 2.0 (April 2019),
stick with Django 1.11 LTS (supported until April 2020) instead. Note, however,
that the end-of-life for Python 3.4 is March 2019.

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 to 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
========================

Simplified URL routing syntax
-----------------------------

The new :func:`django.urls.path()` function allows a simpler, more readable URL
routing syntax. For example, this example from previous Django releases::

 url(r'^articles/(?P<year>[0-9]{4})/$', views.year_archive),

could be written as::

 path('articles/<int:year>/', views.year_archive),

The new syntax supports type coercion of URL parameters. In the example, the
view will receive the ``year`` keyword argument as an integer rather than as
a string. Also, the URLs that will match are slightly less constrained in the
rewritten example. For example, the year 10000 will now match since the year
integers aren't constrained to be exactly four digits long as they are in the
regular expression.

The ``django.conf.urls.url()`` function from previous versions is now available
as :func:`django.urls.re_path`. The old location remains for backwards
compatibility, without an imminent deprecation. The old
``django.conf.urls.include()`` function is now importable from ``django.urls``
so you can use ``from django.urls import include, path, re_path`` in your
URLconfs.

The :doc:`/topics/http/urls` document is rewritten to feature the new syntax
and provide more details.

Mobile-friendly ``contrib.admin``
---------------------------------

The admin is now responsive and supports all major mobile devices. Older
browsers may experience varying levels of graceful degradation.

Window expressions
------------------

The new :class:`~django.db.models.expressions.Window` expression allows
adding an ``OVER`` clause to querysets. You can use :ref:`window functions
<window-functions>` and :ref:`aggregate functions <aggregation-functions>` in
the expression.

Minor features
--------------

:mod:`django.contrib.admin`
~~~~~~~~~~~~~~~~~~~~~~~~~~~

* The new :attr:`.ModelAdmin.autocomplete_fields` attribute and
:meth:`.ModelAdmin.get_autocomplete_fields` method allow using a
`Select2 <https://select2.org>`_ search widget for ``ForeignKey`` and
``ManyToManyField``.

:mod:`django.contrib.auth`
~~~~~~~~~~~~~~~~~~~~~~~~~~

* The default iteration count for the PBKDF2 password hasher is increased from
36,000 to 100,000.

: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 <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 <gdal-raster-vsimem>` in-memory.

* The new :meth:`GDALBand.color_interp()
<django.contrib.gis.gdal.GDALBand.color_interp>` method returns the color
interpretation for the band.

: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
``fastupdate`` and ``gin_pending_list_limit`` parameters.

* The new :class:`~django.contrib.postgres.indexes.GistIndex` class allows
creating ``GiST`` indexes in the database. The new
:class:`~django.contrib.postgres.operations.BtreeGistExtension` migration
operation installs the ``btree_gist`` extension to add support for operator
classes that aren't built-in.

* :djadmin:`inspectdb` can now introspect ``JSONField`` and various
``RangeField``\s (``django.contrib.postgres`` must be in ``INSTALLED_APPS``).

:mod:`django.contrib.sitemaps`
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

* Added the ``protocol`` keyword argument to the
:class:`~django.contrib.sitemaps.GenericSitemap` constructor.

Cache
~~~~~

* ``cache.set_many()`` now returns a list of keys that failed to be inserted.
For the built-in backends, failed inserts can only happen on memcached.

File Storage
~~~~~~~~~~~~

* :meth:`File.open() <django.core.files.File.open>` can be used as a context
manager, e.g. ``with file.open() as f:``.

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
~~~~~~~~~~~~~

* The new :attr:`.ContextMixin.extra_context` attribute allows adding context
in ``View.as_view()``.

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.

* 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 <https://docs.oracle.com/en/database/oracle/oracle-database/18/drdaa/
intro-to-tools-and-products-supporting-migraiton.htmlGUID-14E4817B-F3BC-4D99
-B471-A0ACDC303CC9>`__.

* 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.

* :meth:`.QuerySet.earliest`, :meth:`.QuerySet.latest`, and
:attr:`Meta.get_latest_by <django.db.models.Options.get_latest_by>` now
allow ordering by several fields.

* Added the :class:`~django.db.models.functions.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.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.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.

* :meth:`.CursorWrapper.callproc()` now takes an optional dictionary of keyword
parameters, if the backend supports this feature. Of Django's built-in
backends, only Oracle supports it.

* The new :meth:`connection.execute_wrapper()
<django.db.backends.base.DatabaseWrapper.execute_wrapper>` method allows
:doc:`installing wrappers around execution of database queries
</topics/db/instrumentation>`.

* The new ``filter`` argument for built-in aggregates allows :ref:`adding
different conditionals <conditional-aggregation>` to multiple aggregations
over the same fields or relations.

* Added support for expressions in :attr:`Meta.ordering
<django.db.models.Options.ordering>`.

* The new ``named`` parameter of :meth:`.QuerySet.values_list` allows fetching
results as named tuples.

* The new :class:`.FilteredRelation` class allows adding an ``ON`` clause to
querysets.

Pagination
~~~~~~~~~~

* Added :meth:`Paginator.get_page() <django.core.paginator.Paginator.get_page>`
to provide the documented pattern of handling invalid page numbers.

Requests and Responses
~~~~~~~~~~~~~~~~~~~~~~

* The :djadmin:`runserver` Web server supports HTTP 1.1.

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`.

Validators
~~~~~~~~~~

* The new :class:`.ProhibitNullCharactersValidator` disallows the null
character in the input of the :class:`~django.forms.CharField` form field
and its subclasses. Null character input was observed from vulnerability
scanning tools. Most databases silently discard null characters, but
psycopg2 2.7+ raises an exception when trying to save a null character to
a char/text field with PostgreSQL.

.. _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. Python's :option:`-b` option may help detect
that mistake in your code.

For example, ``reverse()`` now uses ``str()`` instead of ``force_text()`` to
coerce the ``args`` and ``kwargs`` it receives, prior to their placement in
the URL. For bytestrings, this creates a string with an undesired ``b`` prefix
as well as additional quotes (``str(b'foo')`` is ``"b'foo'"``). To adapt, call
``decode()`` on the bytestring before passing it to ``reverse()``.

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``.

* To enable support for :class:`~django.db.models.expressions.Window`
expressions, set ``DatabaseFeatures.supports_over_clause`` to ``True``. You
may need to customize the ``DatabaseOperations.window_start_rows_start_end()``
and/or ``window_start_range_start_end()`` methods.

* 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.

* The first argument of ``DatabaseCreation._clone_test_db()`` and
``get_test_db_clone_settings()`` is now ``suffix`` rather
than ``number`` (in case you want to rename the signatures in your backend
for consistency). ``django.test`` also now passes those values as strings
rather than as integers.

* Third-party database backends should add a
``DatabaseIntrospection.get_sequences()`` method based on the stub in
``BaseDatabaseIntrospection``.

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.

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.

In addition, because of a table alteration limitation of SQLite, it's prohibited
to perform :class:`~django.db.migrations.operations.RenameModel` and
:class:`~django.db.migrations.operations.RenameField` operations on models or
fields referenced by other models in a transaction. In order to allow migrations
containing these operations to be applied, you must set the
``Migration.atomic`` attribute to ``False``.

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 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
<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 concatenat