--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/web/lib/django/contrib/sessions/backends/db.py	Wed Jan 20 00:34:04 2010 +0100
@@ -0,0 +1,73 @@
+import datetime
+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
+from django.utils.encoding import force_unicode
+
+class SessionStore(SessionBase):
+    """
+    Implements database session store.
+    """
+    def load(self):
+        try:
+            s = Session.objects.get(
+                session_key = self.session_key,
+                expire_date__gt=datetime.datetime.now()
+            )
+            return self.decode(force_unicode(s.session_data))
+        except (Session.DoesNotExist, SuspiciousOperation):
+            self.create()
+            return {}
+
+    def exists(self, session_key):
+        try:
+            Session.objects.get(session_key=session_key)
+        except Session.DoesNotExist:
+            return False
+        return True
+
+    def create(self):
+        while True:
+            self.session_key = self._get_new_session_key()
+            try:
+                # Save immediately to ensure we have a unique entry in the
+                # database.
+                self.save(must_create=True)
+            except CreateError:
+                # Key wasn't unique. Try again.
+                continue
+            self.modified = True
+            self._session_cache = {}
+            return
+
+    def save(self, must_create=False):
+        """
+        Saves the current session data to the database. If 'must_create' is
+        True, a database error will be raised if the saving operation doesn't
+        create a *new* entry (as opposed to possibly updating an existing
+        entry).
+        """
+        obj = Session(
+            session_key = self.session_key,
+            session_data = self.encode(self._get_session(no_load=must_create)),
+            expire_date = self.get_expiry_date()
+        )
+        sid = transaction.savepoint()
+        try:
+            obj.save(force_insert=must_create)
+        except IntegrityError:
+            if must_create:
+                transaction.savepoint_rollback(sid)
+                raise CreateError
+            raise
+
+    def delete(self, session_key=None):
+        if session_key is None:
+            if self._session_key is None:
+                return
+            session_key = self._session_key
+        try:
+            Session.objects.get(session_key=session_key).delete()
+        except Session.DoesNotExist:
+            pass