Refactor

Author: WaVEV

django_mongodb_backend/cache.py

@@ -67,10 +67,11 @@ def _filter_expired(self, expired=False):
         Create a filter to exclude expired data by default
         or include only expired data if `expired` is True.
         """
-        # The data isn't expired if expires_at > now or is null.
-        not_expired_filter = [{"expires_at": {"$gte": datetime.utcnow()}}, {"expires_at": None}]
-        operator = "$nor" if expired else "$or"
-        return {operator: not_expired_filter}
+        return (
+            {"expires_at": {"$lt": datetime.utcnow()}}
+            if expired
+            else {"expires_at": {"$gte": datetime.utcnow()}}
+        )
 
     def get_many(self, keys, version=None):
         if not keys: