Update app.py

app.py

@@ -12,7 +12,7 @@ embeddings = OpenAIEmbeddings()
 
 from langchain.vectorstores import Chroma
 
-from langchain.chains import RetrievalQA
+from langchain.chains import ConversationalRetrievalChain
 
 def loading_pdf():
     return "Loading..."
@@ -24,11 +24,12 @@ def pdf_changes(pdf_doc):
     db = Chroma.from_documents(texts, embeddings)
     retriever = db.as_retriever()
     global qa 
-    qa = RetrievalQA.from_chain_type(
+    qa = ConversationalRetrievalChain.from_llm(
         llm=OpenAI(temperature=0.5), 
-        chain_type="stuff", 
         retriever=retriever, 
-        return_source_documents=True)
+        return_source_documents=False)
+    global chat_history
+    chat_history = []
     return "Ready"
 
 def add_text(history, text):
@@ -43,9 +44,9 @@ def bot(history):
 def infer(question):
     
     query = question
-    result = qa({"query": query})
+    result = qa({"question": query, "chat_history": chat_history})
     #print(result)
-    return result
+    return result["answer"]
 
 css="""
 #col-container {max-width: 700px; margin-left: auto; margin-right: auto;}