django/docs/releases/1.2.5.txt

==========================
Django 1.2.5 release notes
==========================

Welcome to Django 1.2.5!

This is the fifth "bugfix" release in the Django 1.2 series,
improving the stability and performance of the Django 1.2 codebase.

With four exceptions, Django 1.2.5 maintains backwards compatibility
with Django 1.2.4. It also contains a number of fixes and other
improvements. Django 1.2.5 is a recommended upgrade for any
development or deployment currently using or targeting Django 1.2.

For full details on the new features, backwards incompatibilities, and
deprecated features in the 1.2 branch, see the :doc:`/releases/1.2`.

Backwards incompatible changes
==============================

CSRF exception for AJAX requests
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Django includes a CSRF-protection mechanism, which makes use of a
token inserted into outgoing forms. Middleware then checks for the
token's presence on form submission, and validates it.

Prior to Django 1.2.5, our CSRF protection made an exception for AJAX
requests, on the following basis:

    * Many AJAX toolkits add an X-Requested-With header when using
      XMLHttpRequest.

    * Browsers have strict same-origin policies regarding
      XMLHttpRequest.

    * In the context of a browser, the only way that a custom header
      of this nature can be added is with XMLHttpRequest.

Therefore, for ease of use, we did not apply CSRF checks to requests
that appeared to be AJAX on the basis of the X-Requested-With header.
The Ruby on Rails web framework had a similar exemption.

Recently, engineers at Google made members of the Ruby on Rails
development team aware of a combination of browser plugins and
redirects which can allow an attacker to provide custom HTTP headers
on a request to any website. This can allow a forged request to appear
to be an AJAX request, thereby defeating CSRF protection which trusts
the same-origin nature of AJAX requests.

Michael Koziarski of the Rails team brought this to our attention, and
we were able to produce a proof-of-concept demonstrating the same
vulnerability in Django's CSRF handling.

To remedy this, Django will now apply full CSRF validation to all
requests, regardless of apparent AJAX origin. This is technically
backwards-incompatible, but the security risks have been judged to
outweigh the compatibility concerns in this case.

Additionally, Django will now accept the CSRF token in the custom HTTP
header X-CSRFTOKEN, as well as in the form submission itself, for ease
of use with popular JavaScript toolkits which allow insertion of
custom headers into all AJAX requests.

Please see the :ref:`CSRF docs for example jQuery code <csrf-ajax>`
that demonstrates this technique, ensuring that you are looking at the
documentation for your version of Django, as the exact code necessary
is different for some older versions of Django.

FileField no longer deletes files
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

In earlier Django versions, when a model instance containing a
:class:`~django.db.models.FileField` was deleted,
:class:`~django.db.models.FileField` took it upon itself to also delete the
file from the backend storage. This opened the door to several potentially
serious data-loss scenarios, including rolled-back transactions and fields on
different models referencing the same file. In Django 1.2.5,
:class:`~django.db.models.FileField` will never delete files from the backend
storage. If you need cleanup of orphaned files, you'll need to handle it
yourself (for instance, with a custom management command that can be run
manually or scheduled to run periodically via e.g. cron).

Use of custom SQL to load initial data in tests
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Django provides a custom SQL hooks as a way to inject hand-crafted SQL
into the database synchronization process. One of the possible uses
for this custom SQL is to insert data into your database. If your
custom SQL contains ``INSERT`` statements, those insertions will be
performed every time your database is synchronized. This includes the
synchronization of any test databases that are created when you run a
test suite.

However, in the process of testing the Django 1.3, it was discovered
that this feature has never completely worked as advertised. When
using database backends that don't support transactions, or when using
a TransactionTestCase, data that has been inserted using custom SQL
will not be visible during the testing process.

Unfortunately, there was no way to rectify this problem without
introducing a backwards incompatibility. Rather than leave
SQL-inserted initial data in an uncertain state, Django now enforces
the policy that data inserted by custom SQL will *not* be visible
during testing.

This change only affects the testing process. You can still use custom
SQL to load data into your production database as part of the syncdb
process. If you require data to exist during test conditions, you
should either insert it using :ref:`test fixtures
<topics-testing-fixtures>`, or using the ``setUp()`` method of your
test case.

ModelAdmin.lookup_allowed signature changed
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Django 1.2.4 introduced a method ``lookup_allowed`` on ``ModelAdmin``, to cope
with a security issue (changeset `[15033]
<http://code.djangoproject.com/changeset/15033>`_). Although this method was
never documented, it seems some people have overridden ``lookup_allowed``,
especially to cope with regressions introduced by that changeset. While the
method is still undocumented and not marked as stable, it may be helpful to know
that the signature of this function has changed.