==========================
Django 1.8.2 release notes
==========================

*May 20, 2015*

Django 1.8.2 fixes a security issue and several bugs in 1.8.1.

Fixed session flushing in the ``cached_db`` backend
===================================================

A change to ``session.flush()`` in the ``cached_db`` session backend in Django
1.8 mistakenly sets the session key to an empty string rather than ``None``. An
empty string is treated as a valid session key and the session cookie is set
accordingly. Any users with an empty string in their session cookie will use
the same session store. ``session.flush()`` is called by
``django.contrib.auth.logout()`` and, more seriously, by
``django.contrib.auth.login()`` when a user switches accounts. If a user is
logged in and logs in again to a different account (without logging out) the
session is flushed to avoid reuse. After the session is flushed (and its
session key becomes ``''``) the account details are set on the session and the
session is saved. Any users with an empty string in their session cookie will
now be logged into that account.

Bugfixes
========

* Fixed check for template engine alias uniqueness (:ticket:`24685`).

* Fixed crash when reusing the same ``Case`` instance in a query
  (:ticket:`24752`).

* Corrected join promotion for ``Case`` expressions. For example, annotating a
  query with a  ``Case`` expression could unexpectedly filter out results
  (:ticket:`24766`).

* Fixed negated ``Q`` objects in expressions. Cases like
  ``Case(When(~Q(friends__age__lte=30)))`` tried to generate a subquery which
  resulted in a crash (:ticket:`24705`).

* Fixed incorrect GROUP BY clause generation on MySQL when the query's model
  has a self-referential foreign key (:ticket:`24748`).

* Implemented ``ForeignKey.get_db_prep_value()`` so that ``ForeignKey``\s
  pointing to :class:`~django.db.models.UUIDField` and inheritance on models
  with ``UUIDField`` primary keys work correctly (:ticket:`24698`,
  :ticket:`24712`).

* Fixed ``isnull`` lookup for ``HStoreField`` (:ticket:`24751`).

* Fixed a MySQL crash when a migration removes a combined index (unique_together
  or index_together) containing a foreign key (:ticket:`24757`).

* Fixed session cookie deletion when using :setting:`SESSION_COOKIE_DOMAIN`
  (:ticket:`24799`).

* On PostgreSQL, when no access is granted for the ``postgres`` database,
  Django now falls back to the default database when it normally requires a
  "no database" connection (:ticket:`24791`).

* Fixed display of ``contrib.admin``’s ``ForeignKey`` widget when it's used
  in a row with other fields (:ticket:`24784`).
