import datetime
from django.conf import settings
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,router
from django.utils.encoding import force_unicode
class SessionStore(SessionBase):
"""
Implements database session store.
"""
def __init__(self, session_key=None):
super(SessionStore, self).__init__(session_key)
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()
)
using = router.db_for_write(Session, instance=obj)
sid = transaction.savepoint(using=using)
try:
obj.save(force_insert=must_create, using=using)
except IntegrityError:
if must_create:
transaction.savepoint_rollback(sid, using=using)
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
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