1 import datetime

     2 from django.conf import settings

     3 from django.contrib.sessions.models import Session

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

     5 from django.core.exceptions import SuspiciousOperation

     6 from django.db import IntegrityError, transaction, router

     7 from django.utils.encoding import force_unicode

     8 

     9 class SessionStore(SessionBase):

    10     """

    11     Implements database session store.

    12     """

    13     def __init__(self, session_key=None):

    14         super(SessionStore, self).__init__(session_key)

    15 

    16     def load(self):

    17         try:

    18             s = Session.objects.get(

    19                 session_key = self.session_key,

    20                 expire_date__gt=datetime.datetime.now()

    21             )

    22             return self.decode(force_unicode(s.session_data))

    23         except (Session.DoesNotExist, SuspiciousOperation):

    24             self.create()

    25             return {}

    26 

    27     def exists(self, session_key):

    28         try:

    29             Session.objects.get(session_key=session_key)

    30         except Session.DoesNotExist:

    31             return False

    32         return True

    33 

    34     def create(self):

    35         while True:

    36             self.session_key = self._get_new_session_key()

    37             try:

    38                 # Save immediately to ensure we have a unique entry in the

    39                 # database.

    40                 self.save(must_create=True)

    41             except CreateError:

    42                 # Key wasn't unique. Try again.

    43                 continue

    44             self.modified = True

    45             self._session_cache = {}

    46             return

    47 

    48     def save(self, must_create=False):

    49         """

    50         Saves the current session data to the database. If 'must_create' is

    51         True, a database error will be raised if the saving operation doesn't

    52         create a *new* entry (as opposed to possibly updating an existing

    53         entry).

    54         """

    55         obj = Session(

    56             session_key = self.session_key,

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

    58             expire_date = self.get_expiry_date()

    59         )

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

    61         sid = transaction.savepoint(using=using)

    62         try:

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

    64         except IntegrityError:

    65             if must_create:

    66                 transaction.savepoint_rollback(sid, using=using)

    67                 raise CreateError

    68             raise

    69 

    70     def delete(self, session_key=None):

    71         if session_key is None:

    72             if self._session_key is None:

    73                 return

    74             session_key = self._session_key

    75         try:

    76             Session.objects.get(session_key=session_key).delete()

    77         except Session.DoesNotExist:

    78             pass