Четвёртая ссылка в гугле:
from django.conf import settings
from django.core.cache import cache, get_cache
from django.utils.importlib import import_module
class UserRestrictMiddleware(object):
def process_request(self, request):
"""
Checks if different session exists for user and deletes it.
"""
if request.user.is_authenticated():
cache = get_cache('default')
cache_timeout = 86400
cache_key = "user_pk_%s_restrict" % request.user.pk
cache_value = cache.get(cache_key)
if cache_value is not None:
if request.session.session_key != cache_value:
engine = import_module(settings.SESSION_ENGINE)
session = engine.SessionStore(session_key=cache_value)
session.delete()
cache.set(cache_key, request.session.session_key,
cache_timeout)
else:
cache.set(cache_key, request.session.session_key, cache_timeout)