Adds to Melange a tags framework based on taggable-mixin.
The taggable-mixin allowed only tag per Datastore model. This is extended
framework allows any arbitrary number of tags per Datastore model. Also,
now one can define different models for different Tag types which are all
inherited from the base Tag model provided by taggable-mixin.
The GHOPTask model makes use of 2 tags per model, one for difficulty and the
other for task_type, both using the tags framework.
Reviewed by: Paweł Sołyga
from django.contrib.sessions.backends.base import SessionBase, CreateError
from django.core.cache import cache
class SessionStore(SessionBase):
"""
A cache-based session store.
"""
def __init__(self, session_key=None):
self._cache = cache
super(SessionStore, self).__init__(session_key)
def load(self):
session_data = self._cache.get(self.session_key)
if session_data is not None:
return session_data
self.create()
return {}
def create(self):
# Because a cache can fail silently (e.g. memcache), we don't know if
# we are failing to create a new session because of a key collision or
# because the cache is missing. So we try for a (large) number of times
# and then raise an exception. That's the risk you shoulder if using
# cache backing.
for i in xrange(10000):
self.session_key = self._get_new_session_key()
try:
self.save(must_create=True)
except CreateError:
continue
self.modified = True
return
raise RuntimeError("Unable to create a new session key.")
def save(self, must_create=False):
if must_create:
func = self._cache.add
else:
func = self._cache.set
result = func(self.session_key, self._get_session(no_load=must_create),
self.get_expiry_age())
if must_create and not result:
raise CreateError
def exists(self, session_key):
if self._cache.get(session_key):
return True
return False
def delete(self, session_key=None):
if session_key is None:
if self._session_key is None:
return
session_key = self._session_key
self._cache.delete(session_key)