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from django.conf import settings
from django.contrib.sessions.backends.base import SessionBase
from django.core import signing
class SessionStore(SessionBase):
def load(self):
"""
We load the data from the key itself instead of fetching from
some external data store. Opposite of _get_session_key(),
raises BadSignature if signature fails.
"""
try:
return signing.loads(self.session_key,
serializer=self.serializer,
# This doesn't handle non-default expiry dates, see #19201
max_age=settings.SESSION_COOKIE_AGE,
salt='django.contrib.sessions.backends.signed_cookies')
except Exception:
# BadSignature, ValueError, or unpickling exceptions. If any of
# these happen, reset the session.
self.create()
return {}
def create(self):
"""
To create a new key, we simply make sure that the modified flag is set
so that the cookie is set on the client for the current request.
"""
self.modified = True
def save(self, must_create=False):
"""
To save, we get the session key as a securely signed string and then
set the modified flag so that the cookie is set on the client for the
current request.
"""
self._session_key = self._get_session_key()
self.modified = True
def exists(self, session_key=None):
"""
This method makes sense when you're talking to a shared resource, but
it doesn't matter when you're storing the information in the client's
cookie.
"""
return False
def delete(self, session_key=None):
"""
To delete, we clear the session key and the underlying data structure
and set the modified flag so that the cookie is set on the client for
the current request.
"""
self._session_key = ''
self._session_cache = {}
self.modified = True
def cycle_key(self):
"""
Keeps the same data but with a new key. To do this, we just have to
call ``save()`` and it will automatically save a cookie with a new key
at the end of the request.
"""
self.save()
def _get_session_key(self):
"""
Most session backends don't need to override this method, but we do,
because instead of generating a random string, we want to actually
generate a secure url-safe Base64-encoded string of data as our
session key.
"""
session_cache = getattr(self, '_session_cache', {})
return signing.dumps(session_cache, compress=True,
salt='django.contrib.sessions.backends.signed_cookies',
serializer=self.serializer)
@classmethod
def clear_expired(cls):
pass
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