Fixed #18023 -- Documented simplejson issues.

Thanks Luke Plant for reporting the issue and Alex Ogier for thoroughly
investigating it.
This commit is contained in:
Aymeric Augustin 2012-08-20 21:21:00 +02:00
parent 1288572d92
commit 610746f6cb
1 changed files with 59 additions and 3 deletions

View File

@ -172,6 +172,54 @@ 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.
.. _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
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
@ -282,13 +330,21 @@ Miscellaneous
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``
~~~~~~~~~~~~~~~~~~~~~~