Fixed #13200 -- Updated the DB session backend to make full use of routers,...

from django.contrib.sessions.models import Session

from django.contrib.sessions.backends.base import SessionBase, CreateError

from django.core.exceptions import SuspiciousOperation

from django.db import IntegrityError, transaction, DEFAULT_DB_ALIAS

from django.db import IntegrityError, transaction, router

from django.utils.encoding import force_unicode

class SessionStore(SessionBase):

    Implements database session store.

    """

    def __init__(self, session_key=None):

        self.using = getattr(settings, "SESSION_DB_ALIAS", DEFAULT_DB_ALIAS)

        super(SessionStore, self).__init__(session_key)

    def load(self):

            session_data = self.encode(self._get_session(no_load=must_create)),

            expire_date = self.get_expiry_date()

        )

        sid = transaction.savepoint(using=self.using)

        using = router.db_for_write(Session, instance=obj)

        sid = transaction.savepoint(using=using)

        try:

            obj.save(force_insert=must_create)

            obj.save(force_insert=must_create, using=using)

        except IntegrityError:

            if must_create:

                transaction.savepoint_rollback(sid, using=self.using)

                transaction.savepoint_rollback(sid, using=using)

                raise CreateError

            raise

.. setting:: SESSION_EXPIRE_AT_BROWSER_CLOSE

SESSION_DB_ALIAS

----------------

.. versionadded:: 1.2

Default: ``None``

If you're using database-backed session storage, this selects the database

alias that will be used to store session data. By default, Django will use

the ``default`` database, but you can store session data on any database

you choose.

SESSION_EXPIRE_AT_BROWSER_CLOSE

-------------------------------

If you want to use a database-backed session, you need to add

``'django.contrib.sessions'`` to your ``INSTALLED_APPS`` setting.

If you want to store your session data on a database other than ``default``

alias, you should set the :setting:`SESSION_DB_ALIAS` setting.

Once you have configured your installation, run ``manage.py syncdb``

to install the single database table that stores session data.

.. versionadded:: 1.2

   The :setting:`SESSION_DB_ALIAS` setting was added in Django 1.2. It

   is not required in earlier versions.

Using cached sessions

---------------------