Update app.py

app.py

@@ -329,7 +329,7 @@ def get_response(collection_name, vector_db, qa_chain, history, query, file):
         chat_history_tuples.append((message[0], message[1]))
 
     #vincent added 20250211
-    if add.count == 0:
+    if app.count == 0:
        collection_name, vector_db, qa_chain = build_qa_chain(collection_name, vector_db, file)    
     result = qa_chain.invoke(
         {"question": query, "chat_history": chat_history_tuples}, return_only_outputs=True