Investigating strange error

cdplib/db_handlers/MongodbHandler.py

@@ -291,7 +291,7 @@ class MongodbHandler:
 
         #print(data[0])
         #print(len(data[0]))
-        if len(data[0]) != 0:
+        if data.retrieved() != 0:
             if return_as_dataframe:
                 return self.convert_mongo_data_into_dataframe(data, index, collection_name)
             else: