django/docs/releases/1.5-alpha-1.txt

==============================
Django 1.5 alpha release notes
==============================

October 25, 2012.

Welcome to Django 1.5 alpha!

This is the first in a series of preview/development releases leading up to the
eventual release of Django 1.5, scheduled for December 2012. This release is
primarily targeted at developers who are interested in trying out new features
and testing the Django codebase to help identify and resolve bugs prior to the
final 1.5 release.

As such, this release is *not* intended for production use, and any such use
is discouraged.

In particular, we need the community's help to test Django 1.5's new `Python 3
support`_ -- not just to report bugs on Python 3, but also regressions on Python
2. While Django is very conservative with regards to backwards compatibility,
mistakes are always possible, and it's likely that the Python 3 refactoring work
introduced some regressions.

Django 1.5 alpha includes various `new features`_ and some minor `backwards
incompatible changes`_. There are also some features that have been dropped,
which are detailed in :doc:`our deprecation plan </internals/deprecation>`,
and we've `begun the deprecation process for some features`_.

.. _`new features`: `What's new in Django 1.5`_
.. _`backwards incompatible changes`: `Backwards incompatible changes in 1.5`_
.. _`begun the deprecation process for some features`: `Features deprecated in 1.5`_

Overview
========

The biggest new feature in Django 1.5 is the `configurable User model`_. Before
Django 1.5, applications that wanted to use Django's auth framework
(:mod:`django.contrib.auth`) were forced to use Django's definition of a "user".
In Django 1.5, you can now swap out the ``User`` model for one that you write
yourself. This could be a simple extension to the existing ``User`` model -- for
example, you could add a Twitter or Facebook ID field -- or you could completely
replace the ``User`` with one totally customized for your site.

Django 1.5 is also the first release with `Python 3 support`_! We're labeling
this support "experimental" because we don't yet consider it production-ready,
but everything's in place for you to start porting your apps to Python 3.
Our next release, Django 1.6, will support Python 3 without reservations.

Other notable new features in Django 1.5 include:

* `Support for saving a subset of model's fields`_ -
  :meth:`Model.save() <django.db.models.Model.save()>` now accepts an
  ``update_fields`` argument, letting you specify which fields are
  written back to the database when you call ``save()``. This can help
  in high-concurrency operations, and can improve performance.

* Better `support for streaming responses <#explicit-streaming-responses>`_ via
  the new  :class:`~django.http.StreamingHttpResponse` response class.

* `GeoDjango`_ now supports PostGIS 2.0.

* ... and more; `see below <#what-s-new-in-django-1-5>`_.

Wherever possible we try to introduce new features in a backwards-compatible
manner per :doc:`our API stability policy </misc/api-stability>` policy.
However, as with previous releases, Django 1.5 ships with some minor
`backwards incompatible changes`_; people upgrading from previous versions
of Django should read that list carefully.

One deprecated feature worth noting is the shift to "new-style" :ttag:`url` tag.
Prior to Django 1.3, syntax like ``{% url myview %}`` was interpreted
incorrectly (Django considered ``"myview"`` to be a literal name of a view, not
a template variable named ``myview``). Django 1.3 and above introduced the
``{% load url from future %}`` syntax to bring in the corrected behavior where
``myview`` was seen as a variable.

The upshot of this is that if you are not using ``{% load url from future %}``
in your templates, you'll need to change tags like ``{% url myview %}`` to
``{% url "myview" %}``. If you *were* using ``{% load url from future %}`` you
can simply remove that line under Django 1.5

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

Django 1.5 requires Python 2.6.5 or above, though we **highly recommended**
Python 2.7.3 or above. Support for Python 2.5 and below has been dropped.

This change should affect only a small number of Django users, as most
operating-system vendors today are shipping Python 2.6 or newer as their default
version. If you're still using Python 2.5, however, you'll need to stick to
Django 1.4 until you can upgrade your Python version. Per :doc:`our support
policy </internals/release-process>`, Django 1.4 will continue to receive
security support until the release of Django 1.6.

Django 1.5 does not run on a Jython final release, because Jython's latest
release doesn't currently support Python 2.6. However, Jython currently does
offer an alpha release featuring 2.7 support, and Django 1.5 supports that alpha
release.

Python 3 support
~~~~~~~~~~~~~~~~

Django 1.5 introduces support for Python 3 - specifically, Python
3.2 and above. This comes in the form of a **single** codebase; you don't
need to install a different version of Django on Python 3. This means that
you can write application targeted for just Python 2, just Python 3, or single
applications that support both platforms.

However, we're labeling this support "experimental" for now: although it's
received extensive testing via our automated test suite, it's received very
little real-world testing. We've done our best to eliminate bugs, but we can't
be sure we covered all possible uses of Django. Further, Django's more than a
web framework; it's an ecosystem of pluggable components. At this point, very
few third-party applications have been ported to Python 3, so it's unlikely
that a real-world application will have all its dependencies satisfied under
Python 3.

Thus, we're recommending that Django 1.5 not be used in production under Python
3. Instead, use this opportunity to begin :doc:`porting applications to Python 3
</topics/python3>`. If you're an author of a pluggable component, we encourage you
to start porting now.

We plan to offer first-class, production-ready support for Python 3 in our next
release, Django 1.6.

What's new in Django 1.5
========================

Configurable User model
~~~~~~~~~~~~~~~~~~~~~~~

In Django 1.5, you can now use your own model as the store for user-related
data. If your project needs a username with more than 30 characters, or if
you want to store usernames in a format other than first name/last name, or
you want to put custom profile information onto your User object, you can
now do so.

If you have a third-party reusable application that references the User model,
you may need to make some changes to the way you reference User instances. You
should also document any specific features of the User model that your
application relies upon.

See the :ref:`documentation on custom User models <auth-custom-user>` for
more details.

Support for saving a subset of model's fields
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The method :meth:`Model.save() <django.db.models.Model.save()>` has a new
keyword argument ``update_fields``. By using this argument it is possible to
save only a select list of model's fields. This can be useful for performance
reasons or when trying to avoid overwriting concurrent changes.

Deferred instances (those loaded by .only() or .defer()) will automatically
save just the loaded fields. If any field is set manually after load, that
field will also get updated on save.

See the :meth:`Model.save() <django.db.models.Model.save()>` documentation for
more details.

Caching of related model instances
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

When traversing relations, the ORM will avoid re-fetching objects that were
previously loaded. For example, with the tutorial's models::

    >>> first_poll = Poll.objects.all()[0]
    >>> first_choice = first_poll.choice_set.all()[0]
    >>> first_choice.poll is first_poll
    True

In Django 1.5, the third line no longer triggers a new SQL query to fetch
``first_choice.poll``; it was set by the second line.

For one-to-one relationships, both sides can be cached. For many-to-one
relationships, only the single side of the relationship can be cached. This
is particularly helpful in combination with ``prefetch_related``.

Explicit support for streaming responses
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Before Django 1.5, it was possible to create a streaming response by passing
an iterator to :class:`~django.http.HttpResponse`. But this was unreliable:
any middleware that accessed the :attr:`~django.http.HttpResponse.content`
attribute would consume the iterator prematurely.

You can now explicitly generate a streaming response with the new
:class:`~django.http.StreamingHttpResponse` class. This class exposes a
:class:`~django.http.StreamingHttpResponse.streaming_content` attribute which
is an iterator.

Since :class:`~django.http.StreamingHttpResponse` does not have a ``content``
attribute, middleware that needs access to the response content must test for
streaming responses and behave accordingly. See :ref:`response-middleware` for
more information.

``{% verbatim %}`` template tag
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

To make it easier to deal with javascript templates which collide with Django's
syntax, you can now use the :ttag:`verbatim` block tag to avoid parsing the
tag's content.

Retrieval of ``ContentType`` instances associated with proxy models
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The methods :meth:`ContentTypeManager.get_for_model() <django.contrib.contenttypes.models.ContentTypeManager.get_for_model()>`
and :meth:`ContentTypeManager.get_for_models() <django.contrib.contenttypes.models.ContentTypeManager.get_for_models()>`
have a new keyword argument – respectively ``for_concrete_model`` and ``for_concrete_models``.
By passing ``False`` using this argument it is now possible to retrieve the
:class:`ContentType <django.contrib.contenttypes.models.ContentType>`
associated with proxy models.

New ``view`` variable in class-based views context
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

In all :doc:`generic class-based views </topics/class-based-views/index>`
(or any class-based view inheriting from ``ContextMixin``), the context dictionary
contains a ``view`` variable that points to the ``View`` instance.

GeoDjango
~~~~~~~~~

* :class:`~django.contrib.gis.geos.LineString` and
  :class:`~django.contrib.gis.geos.MultiLineString` GEOS objects now support the
  :meth:`~django.contrib.gis.geos.GEOSGeometry.interpolate()` and
  :meth:`~django.contrib.gis.geos.GEOSGeometry.project()` methods
  (so-called linear referencing).

* The ``wkb`` and ``hex`` properties of
  :class:`~django.contrib.gis.geos.GEOSGeometry` objects preserve the Z
  dimension.

* Support for PostGIS 2.0 has been added and support for GDAL < 1.5 has been
  dropped.

Minor features
~~~~~~~~~~~~~~

Django 1.5 also includes several smaller improvements worth noting:

* The template engine now interprets ``True``, ``False`` and ``None`` as the
  corresponding Python objects.

* :mod:`django.utils.timezone` provides a helper for converting aware
  datetimes between time zones. See :func:`~django.utils.timezone.localtime`.

* The generic views support OPTIONS requests.

* Management commands do not raise ``SystemExit`` any more when called by code
  from :ref:`call_command <call-command>`. Any exception raised by the command
  (mostly :ref:`CommandError <ref-command-exceptions>`) is propagated.

* The dumpdata management command outputs one row at a time, preventing
  out-of-memory errors when dumping large datasets.

* In the localflavor for Canada, "pq" was added to the acceptable codes for
  Quebec. It's an old abbreviation.

* The :ref:`receiver <connecting-receiver-functions>` decorator is now able to
  connect to more than one signal by supplying a list of signals.

* In the admin, you can now filter users by groups which they are members of.

* :meth:`QuerySet.bulk_create()
  <django.db.models.query.QuerySet.bulk_create>` now has a batch_size
  argument. By default the batch_size is unlimited except for SQLite where
  single batch is limited so that 999 parameters per query isn't exceeded.

* The :setting:`LOGIN_URL` and :setting:`LOGIN_REDIRECT_URL` settings now also
  accept view function names and
  :ref:`named URL patterns <naming-url-patterns>`. This allows you to reduce
  configuration duplication. More information can be found in the
  :func:`~django.contrib.auth.decorators.login_required` documentation.

* Django now provides a mod_wsgi :doc:`auth handler
  </howto/deployment/wsgi/apache-auth>`.

* The :meth:`QuerySet.delete() <django.db.models.query.QuerySet.delete>`
  and :meth:`Model.delete() <django.db.models.Model.delete()>` can now take
  fast-path in some cases. The fast-path allows for less queries and less
  objects fetched into memory. See :meth:`QuerySet.delete()
  <django.db.models.query.QuerySet.delete>` for details.

* An instance of :class:`~django.core.urlresolvers.ResolverMatch` is stored on
  the request as ``resolver_match``.

* By default, all logging messages reaching the ``django`` logger when
  :setting:`DEBUG` is ``True`` are sent to the console (unless you redefine the
  logger in your :setting:`LOGGING` setting).

* When using :class:`~django.template.RequestContext`, it is now possible to
  look up permissions by using ``{% if 'someapp.someperm' in perms %}``
  in templates.

* It's not required any more to have ``404.html`` and ``500.html`` templates in
  the root templates directory. Django will output some basic error messages for
  both situations when those templates are not found. Of course, it's still
  recommended as good practice to provide those templates in order to present
  pretty error pages to the user.

* :mod:`django.contrib.auth` provides a new signal that is emitted
  whenever a user fails to login successfully. See
  :data:`~django.contrib.auth.signals.user_login_failed`

* The loaddata management command now supports an
  :djadminopt:`--ignorenonexistent` option to ignore data for fields that no
  longer exist.

* :meth:`~django.test.SimpleTestCase.assertXMLEqual` and
  :meth:`~django.test.SimpleTestCase.assertXMLNotEqual` new assertions allow
  you to test equality for XML content at a semantic level, without caring for
  syntax differences (spaces, attribute order, etc.).

Backwards incompatible changes in 1.5
=====================================

.. warning::

    In addition to the changes outlined in this section, be sure to review the
    :doc:`deprecation plan </internals/deprecation>` for any features that
    have been removed. If you haven't updated your code within the
    deprecation timeline for a given feature, its removal may appear as a
    backwards incompatible change.

Context in year archive class-based views
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

For consistency with the other date-based generic views,
:class:`~django.views.generic.dates.YearArchiveView` now passes ``year`` in
the context as a :class:`datetime.date` rather than a string.  If you are
using ``{{ year }}`` in your templates, you must replace it with ``{{
year|date:"Y" }}``.

``next_year`` and ``previous_year`` were also added in the context. They are
calculated according to ``allow_empty`` and ``allow_future``.

Context in year and month archive class-based views
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

:class:`~django.views.generic.dates.YearArchiveView` and
:class:`~django.views.generic.dates.MonthArchiveView` were documented to
provide a ``date_list`` sorted in ascending order in the context, like their
function-based predecessors, but it actually was in descending order. In 1.5,
the documented order was restored. You may want to add (or remove) the
``reversed`` keyword when you're iterating on ``date_list`` in a template::

    {% for date in date_list reversed %}

:class:`~django.views.generic.dates.ArchiveIndexView` still provides a
``date_list`` in descending order.

Context in TemplateView
~~~~~~~~~~~~~~~~~~~~~~~

For consistency with the design of the other generic views,
:class:`~django.views.generic.base.TemplateView` no longer passes a ``params``
dictionary into the context, instead passing the variables from the URLconf
directly into the context.

Non-form data in HTTP requests
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

:attr:`request.POST <django.http.HttpRequest.POST>` will no longer include data
posted via HTTP requests with non form-specific content-types in the header.
In prior versions, data posted with content-types other than
``multipart/form-data`` or ``application/x-www-form-urlencoded`` would still
end up represented in the :attr:`request.POST <django.http.HttpRequest.POST>`
attribute. Developers wishing to access the raw POST data for these cases,
should use the :attr:`request.body <django.http.HttpRequest.body>` attribute
instead.

OPTIONS, PUT and DELETE requests in the test client
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Unlike GET and POST, these HTTP methods aren't implemented by web browsers.
Rather, they're used in APIs, which transfer data in various formats such as
JSON or XML. Since such requests may contain arbitrary data, Django doesn't
attempt to decode their body.

However, the test client used to build a query string for OPTIONS and DELETE
requests like for GET, and a request body for PUT requests like for POST. This
encoding was arbitrary and inconsistent with Django's behavior when it
receives the requests, so it was removed in Django 1.5.

If you were using the ``data`` parameter in an OPTIONS or a DELETE request,
you must convert it to a query string and append it to the ``path`` parameter.

If you were using the ``data`` parameter in a PUT request without a
``content_type``, you must encode your data before passing it to the test
client and set the ``content_type`` argument.

System version of :mod:`simplejson` no longer used
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

As explained below, Django 1.5 deprecates
``django.utils.simplejson`` in favor of Python 2.6's built-in :mod:`json`
module. In theory, this change is harmless. Unfortunately, because of
incompatibilities between versions of :mod:`simplejson`, it may trigger errors
in some circumstances.

JSON-related features in Django 1.4 always used ``django.utils.simplejson``.
This module was actually:

- A system version of :mod:`simplejson`, if one was available (ie. ``import
  simplejson`` works), if it was more recent than Django's built-in copy or it
  had the C speedups, or
- The :mod:`json` module from the standard library, if it was available (ie.
  Python 2.6 or greater), or
- A built-in copy of version 2.0.7 of :mod:`simplejson`.

In Django 1.5, those features use Python's :mod:`json` module, which is based
on version 2.0.9 of :mod:`simplejson`.

There are no known incompatibilities between Django's copy of version 2.0.7 and
Python's copy of version 2.0.9. However, there are some incompatibilities
between other versions of :mod:`simplejson`:

- While the :mod:`simplejson` API is documented as always returning unicode
  strings, the optional C implementation can return a byte string. This was
  fixed in Python 2.7.
- :class:`simplejson.JSONEncoder` gained a ``namedtuple_as_object`` keyword
  argument in version 2.2.

More information on these incompatibilities is available in `ticket #18023`_.

The net result is that, if you have installed :mod:`simplejson` and your code
uses Django's serialization internals directly -- for instance
``django.core.serializers.json.DjangoJSONEncoder``, the switch from
:mod:`simplejson` to :mod:`json` could break your code. (In general, changes to
internals aren't documented; we're making an exception here.)

At this point, the maintainers of Django believe that using :mod:`json` from
the standard library offers the strongest guarantee of backwards-compatibility.
They recommend to use it from now on.

.. _ticket #18023: https://code.djangoproject.com/ticket/18023#comment:10

String types of hasher method parameters
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

If you have written a :ref:`custom password hasher <auth_password_storage>`,
your ``encode()``, ``verify()`` or ``safe_summary()`` methods should accept
Unicode parameters (``password``, ``salt`` or ``encoded``). If any of the
hashing methods need byte strings, you can use the
:func:`~django.utils.encoding.force_bytes` utility to encode the strings.

Validation of previous_page_number and next_page_number
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

When using :doc:`object pagination </topics/pagination>`,
the ``previous_page_number()`` and ``next_page_number()`` methods of the
:class:`~django.core.paginator.Page` object did not check if the returned
number was inside the existing page range.
It does check it now and raises an :exc:`~django.core.paginator.InvalidPage`
exception when the number is either too low or too high.

Behavior of autocommit database option on PostgreSQL changed
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

PostgreSQL's autocommit option didn't work as advertised previously. It did
work for single transaction block, but after the first block was left the
autocommit behavior was never restored. This bug is now fixed in 1.5. While
this is only a bug fix, it is worth checking your applications behavior if
you are using PostgreSQL together with the autocommit option.

Session not saved on 500 responses
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Django's session middleware will skip saving the session data if the
response's status code is 500.

Email checks on failed admin login
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Prior to Django 1.5, if you attempted to log into the admin interface and
mistakenly used your email address instead of your username, the admin
interface would provide a warning advising that your email address was
not your username. In Django 1.5, the introduction of
:ref:`custom User models <auth-custom-user>` has required the removal of this
warning. This doesn't change the login behavior of the admin site; it only
affects the warning message that is displayed under one particular mode of
login failure.

Changes in tests execution
~~~~~~~~~~~~~~~~~~~~~~~~~~

Some changes have been introduced in the execution of tests that might be
backward-incompatible for some testing setups:

Database flushing in ``django.test.TransactionTestCase``
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Previously, the test database was truncated *before* each test run in a
:class:`~django.test.TransactionTestCase`.

In order to be able to run unit tests in any order and to make sure they are
always isolated from each other, :class:`~django.test.TransactionTestCase` will
now reset the database *after* each test run instead.

No more implicit DB sequences reset
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

:class:`~django.test.TransactionTestCase` tests used to reset primary key
sequences automatically together with the database flushing actions described
above.

This has been changed so no sequences are implicitly reset. This can cause
:class:`~django.test.TransactionTestCase` tests that depend on hard-coded
primary key values to break.

The new :attr:`~django.test.TransactionTestCase.reset_sequences` attribute can
be used to force the old behavior for :class:`~django.test.TransactionTestCase`
that might need it.

Ordering of tests
^^^^^^^^^^^^^^^^^

In order to make sure all ``TestCase`` code starts with a clean database,
tests are now executed in the following order:

* First, all unittests (including :class:`unittest.TestCase`,
  :class:`~django.test.SimpleTestCase`, :class:`~django.test.TestCase` and
  :class:`~django.test.TransactionTestCase`) are run with no particular ordering
  guaranteed nor enforced among them.

* Then any other tests (e.g. doctests) that may alter the database without
  restoring it to its original state are run.

This should not cause any problems unless you have existing doctests which
assume a :class:`~django.test.TransactionTestCase` executed earlier left some
database state behind or unit tests that rely on some form of state being
preserved after the execution of other tests. Such tests are already very
fragile, and must now be changed to be able to run independently.

`cleaned_data` dictionary kept for invalid forms
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The :attr:`~django.forms.Form.cleaned_data` dictionary is now always present
after form validation. When the form doesn't validate, it contains only the
fields that passed validation. You should test the success of the validation
with the :meth:`~django.forms.Form.is_valid()` method and not with the
presence or absence of the :attr:`~django.forms.Form.cleaned_data` attribute
on the form.

Miscellaneous
~~~~~~~~~~~~~

* :class:`django.forms.ModelMultipleChoiceField` now returns an empty
  ``QuerySet`` as the empty value instead of an empty list.

* :func:`~django.utils.http.int_to_base36` properly raises a
  :exc:`~exceptions.TypeError` instead of :exc:`~exceptions.ValueError` for
  non-integer inputs.

* The ``slugify`` template filter is now available as a standard python
  function at :func:`django.utils.text.slugify`. Similarly, ``remove_tags`` is
  available at :func:`django.utils.html.remove_tags`.

* Uploaded files are no longer created as executable by default. If you need
  them to be executable change :setting:`FILE_UPLOAD_PERMISSIONS` to your
  needs. The new default value is ``0666`` (octal) and the current umask value
  is first masked out.

* The :class:`F expressions <django.db.models.F>` supported bitwise operators
  by ``&`` and ``|``. These operators are now available using ``.bitand()`` and
  ``.bitor()`` instead. The removal of ``&`` and ``|`` was done to be
  consistent with :ref:`Q() expressions <complex-lookups-with-q>` and
  ``QuerySet`` combining where the operators are used as boolean AND and OR
  operators.

* The :ttag:`csrf_token` template tag is no longer enclosed in a div. If you need
  HTML validation against pre-HTML5 Strict DTDs, you should add a div around it
  in your pages.

Features deprecated in 1.5
==========================

``AUTH_PROFILE_MODULE`` setting
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

With the introduction of :ref:`custom User models <auth-custom-user>`, there is
no longer any need for a built-in mechanism to store user profile data.

You can still define user profiles models that have a one-to-one relation with
the User model - in fact, for many applications needing to associate data with
a User account, this will be an appropriate design pattern to follow. However,
the ``AUTH_PROFILE_MODULE`` setting, and the
``django.contrib.auth.models.User.get_profile()`` method for accessing
the user profile model, should not be used any longer.

Streaming behavior of :class:`~django.http.HttpResponse`
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Django 1.5 deprecates the ability to stream a response by passing an iterator
to :class:`~django.http.HttpResponse`. If you rely on this behavior, switch to
:class:`~django.http.StreamingHttpResponse`. See above for more details.

In Django 1.7 and above, the iterator will be consumed immediately by
:class:`~django.http.HttpResponse`.

``django.utils.simplejson``
~~~~~~~~~~~~~~~~~~~~~~~~~~~

Since Django 1.5 drops support for Python 2.5, we can now rely on the
:mod:`json` module being available in Python's standard library, so we've
removed our own copy of :mod:`simplejson`. You should now import :mod:`json`
instead of ``django.utils.simplejson``.

Unfortunately, this change might have unwanted side-effects, because of
incompatibilities between versions of :mod:`simplejson` -- see the backwards-
incompatible changes section. If you rely on features added to :mod:`simplejson`
after it became Python's :mod:`json`, you should import :mod:`simplejson`
explicitly.

``django.utils.encoding.StrAndUnicode``
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The ``django.utils.encoding.StrAndUnicode`` mix-in has been deprecated.
Define a ``__str__`` method and apply the
:func:`~django.utils.encoding.python_2_unicode_compatible` decorator instead.

``django.utils.itercompat.product``
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

The ``django.utils.itercompat.product`` function has been deprecated. Use
the built-in :func:`itertools.product` instead.

``django.utils.markup``
~~~~~~~~~~~~~~~~~~~~~~~

The markup contrib module has been deprecated and will follow an accelerated
deprecation schedule. Direct use of python markup libraries or 3rd party tag
libraries is preferred to Django maintaining this functionality in the
framework.