Fixed #17083 -- Allowed sessions to use non-default cache.

django/conf/global_settings.py

@@ -445,6 +445,7 @@ MIDDLEWARE_CLASSES = (
 # SESSIONS #
 ############
 
+SESSION_CACHE_ALIAS = 'default'                         # Cache to store session data if using the cache session backend.
 SESSION_COOKIE_NAME = 'sessionid'                       # Cookie name. This can be whatever you want.
 SESSION_COOKIE_AGE = 60 * 60 * 24 * 7 * 2               # Age of cookie, in seconds (default: 2 weeks).
 SESSION_COOKIE_DOMAIN = None                            # A string like ".example.com", or None for standard domain cookie.

django/contrib/sessions/backends/cache.py

@@ -1,5 +1,6 @@
+from django.conf import settings
 from django.contrib.sessions.backends.base import SessionBase, CreateError
-from django.core.cache import cache
+from django.core.cache import get_cache
 from django.utils.six.moves import xrange
 
 KEY_PREFIX = "django.contrib.sessions.cache"
@@ -10,7 +11,7 @@ class SessionStore(SessionBase):
     A cache-based session store.
     """
     def __init__(self, session_key=None):
-        self._cache = cache
+        self._cache = get_cache(settings.SESSION_CACHE_ALIAS)
         super(SessionStore, self).__init__(session_key)
 
     @property

django/contrib/sessions/tests.py

@@ -13,8 +13,8 @@ from django.contrib.sessions.backends.file import SessionStore as FileSession
 from django.contrib.sessions.backends.signed_cookies import SessionStore as CookieSession
 from django.contrib.sessions.models import Session
 from django.contrib.sessions.middleware import SessionMiddleware
+from django.core.cache import get_cache
 from django.core import management
-from django.core.cache import DEFAULT_CACHE_ALIAS
 from django.core.exceptions import ImproperlyConfigured, SuspiciousOperation
 from django.http import HttpResponse
 from django.test import TestCase, RequestFactory
@@ -136,8 +136,8 @@ class SessionTestsMixin(object):
         self.assertTrue(self.session.modified)
 
     def test_save(self):
-        if (hasattr(self.session, '_cache') and
-                'DummyCache' in settings.CACHES[DEFAULT_CACHE_ALIAS]['BACKEND']):
+        if (hasattr(self.session, '_cache') and'DummyCache' in
+            settings.CACHES[settings.SESSION_CACHE_ALIAS]['BACKEND']):
             raise unittest.SkipTest("Session saving tests require a real cache backend")
         self.session.save()
         self.assertTrue(self.session.exists(self.session.session_key))
@@ -355,7 +355,8 @@ class CacheDBSessionTests(SessionTestsMixin, TestCase):
 
     backend = CacheDBSession
 
-    @unittest.skipIf('DummyCache' in settings.CACHES[DEFAULT_CACHE_ALIAS]['BACKEND'],
+    @unittest.skipIf('DummyCache' in
+        settings.CACHES[settings.SESSION_CACHE_ALIAS]['BACKEND'],
         "Session saving tests require a real cache backend")
     def test_exists_searches_cache_first(self):
         self.session.save()
@@ -454,6 +455,23 @@ class CacheSessionTests(SessionTestsMixin, unittest.TestCase):
             self.session._session_key = (string.ascii_letters + string.digits) * 20
             self.assertEqual(self.session.load(), {})
 
+    def test_default_cache(self):
+        self.session.save()
+        self.assertNotEqual(get_cache('default').get(self.session.cache_key), None)
+
+    @override_settings(CACHES={
+        'default': {
+            'BACKEND': 'django.core.cache.backends.dummy.DummyCache',
+        },
+        'sessions': {
+            'BACKEND': 'django.core.cache.backends.locmem.LocMemCache',
+        },
+    }, SESSION_CACHE_ALIAS='sessions')
+    def test_non_default_cache(self):
+        self.session.save()
+        self.assertEqual(get_cache('default').get(self.session.cache_key), None)
+        self.assertNotEqual(get_cache('sessions').get(self.session.cache_key), None)
+
 
 class SessionMiddlewareTests(unittest.TestCase):
 

docs/ref/settings.txt

@@ -1693,6 +1693,16 @@ This is useful if you have multiple Django instances running under the same
 hostname. They can use different cookie paths, and each instance will only see
 its own session cookie.
 
+.. setting:: SESSION_CACHE_ALIAS
+
+SESSION_CACHE_ALIAS
+-------------------
+
+Default: ``default``
+
+If you're using :ref:`cache-based session storage <cached-sessions-backend>`,
+this selects the cache to use.
+
 .. setting:: SESSION_COOKIE_SECURE
 
 SESSION_COOKIE_SECURE

docs/releases/1.5.txt

@@ -299,6 +299,9 @@ Django 1.5 also includes several smaller improvements worth noting:
 * RemoteUserMiddleware now forces logout when the REMOTE_USER header
   disappears during the same browser session.
 
+* The :ref:`cache-based session backend <cached-sessions-backend>` can store
+  session data in a non-default cache.
+
 Backwards incompatible changes in 1.5
 =====================================
 

docs/topics/http/sessions.txt

@@ -45,6 +45,8 @@ If you want to use a database-backed session, you need to add
 Once you have configured your installation, run ``manage.py syncdb``
 to install the single database table that stores session data.
 
+.. _cached-sessions-backend:
+
 Using cached sessions
 ---------------------
 
@@ -62,6 +64,13 @@ sure you've configured your cache; see the :doc:`cache documentation
     sessions directly instead of sending everything through the file or
     database cache backends.
 
+If you have multiple caches defined in :setting:`CACHES`, Django will use the
+default cache. To use another cache, set :setting:`SESSION_CACHE_ALIAS` to the
+name of that cache.
+
+.. versionchanged:: 1.5
+    The :setting:`SESSION_CACHE_ALIAS` setting was added.
+
 Once your cache is configured, you've got two choices for how to store data in
 the cache: