Import check to account for new version of MongoEngine

flask_security/datastore.py

@@ -190,7 +190,11 @@ class MongoEngineUserDatastore(MongoEngineDatastore, UserDatastore):
         UserDatastore.__init__(self, user_model, role_model)
 
     def find_user(self, **kwargs):
-        from mongoengine.queryset import Q, QCombination
+        try:
+            from mongoengine.queryset import Q, QCombination
+        except ImportError:
+            from mongoengine.queryset.visitor import Q, QCombination
+
         queries = map(lambda i: Q(**{i[0]: i[1]}), kwargs.items())
         query = QCombination(QCombination.AND, queries)
         return self.user_model.objects(query).first()