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