Fixed #18023 -- Documented simplejson issues.

``content_type``, you must encode your data before passing it to the test

client and set the ``content_type`` argument.

.. _simplejson-incompatibilities:

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

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

:ref:`As explained below <simplejson-deprecation>`, Django 1.5 deprecates

:mod:`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 :mod:`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

:class:`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

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

Features deprecated in 1.5

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

.. _simplejson-deprecation:

``django.utils.simplejson``

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

Since Django 1.5 drops support for Python 2.5, we can now rely on the

:mod:`json` module being in Python's standard library -- so we've removed

our own copy of ``simplejson``. You can safely change any use of

:mod:`django.utils.simplejson` to :mod:`json`.

: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 :mod:`django.utils.simplejson`.

Unfortunately, this change might have unwanted side-effects, because of

incompatibilities between versions of :mod:`simplejson` -- see the

:ref:`backwards-incompatible changes <simplejson-incompatibilities>` section.

If you rely on features added to :mod:`simplejson` after it became Python's

:mod:`json`, you should import :mod:`simplejson` explicitly.

``itercompat.product``

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