app/django/contrib/sessions/backends/db.py

   1 import datetime
   2 from django.contrib.sessions.models import Session
   3 from django.contrib.sessions.backends.base import SessionBase, CreateError
   4 from django.core.exceptions import SuspiciousOperation
   5 from django.db import IntegrityError, transaction
   6 from django.utils.encoding import force_unicode
   7
   8 class SessionStore(SessionBase):
   9     """
  10     Implements database session store.
  11     """
  12     def load(self):
  13         try:
  14             s = Session.objects.get(
  15                 session_key = self.session_key,
  16                 expire_date__gt=datetime.datetime.now()
  17             )
  18             return self.decode(force_unicode(s.session_data))
  19         except (Session.DoesNotExist, SuspiciousOperation):
  20             self.create()
  21             return {}
  22
  23     def exists(self, session_key):
  24         try:
  25             Session.objects.get(session_key=session_key)
  26         except Session.DoesNotExist:
  27             return False
  28         return True
  29
  30     def create(self):
  31         while True:
  32             self.session_key = self._get_new_session_key()
  33             try:
  34                 # Save immediately to ensure we have a unique entry in the
  35                 # database.
  36                 self.save(must_create=True)
  37             except CreateError:
  38                 # Key wasn't unique. Try again.
  39                 continue
  40             self.modified = True
  41             self._session_cache = {}
  42             return
  43
  44     def save(self, must_create=False):
  45         """
  46         Saves the current session data to the database. If 'must_create' is
  47         True, a database error will be raised if the saving operation doesn't
  48         create a *new* entry (as opposed to possibly updating an existing
  49         entry).
  50         """
  51         obj = Session(
  52             session_key = self.session_key,
  53             session_data = self.encode(self._get_session(no_load=must_create)),
  54             expire_date = self.get_expiry_date()
  55         )
  56         sid = transaction.savepoint()
  57         try:
  58             obj.save(force_insert=must_create)
  59         except IntegrityError:
  60             if must_create:
  61                 transaction.savepoint_rollback(sid)
  62                 raise CreateError
  63             raise
  64
  65     def delete(self, session_key=None):
  66         if session_key is None:
  67             if self._session_key is None:
  68                 return
  69             session_key = self._session_key
  70         try:
  71             Session.objects.get(session_key=session_key).delete()
  72         except Session.DoesNotExist:
  73             pass