Update app.py

app.py

@@ -1,5 +1,6 @@
 from langchain.prompts.prompt import PromptTemplate
-from langchain.llms import OpenAI
+# from langchain.llms import OpenAI
+from langchain.llms import OpenAIChat
 from langchain.chains import ChatVectorDBChain
 from langchain.embeddings import HuggingFaceEmbeddings, HuggingFaceInstructEmbeddings
 from langchain.callbacks.base import CallbackManager
@@ -11,6 +12,8 @@ import gradio as gr
 import pickle
 from threading import Lock
 
+prefix_messages = [{"role": "system", "content": "You are a helpful assistant that is very good at answering questions about investments using the information given."}]
+
 model_options = {'all-mpnet-base-v2': "sentence-transformers/all-mpnet-base-v2",
                 'instructor-base': "hkunlp/instructor-base"}
 
@@ -64,7 +67,8 @@ QA_PROMPT = PromptTemplate(template=template, input_variables=["question", "cont
 
 
 def get_chain(vectorstore):
-    llm = OpenAI(streaming=True, callback_manager=CallbackManager([StreamingStdOutCallbackHandler()]), verbose=True, temperature=0)
+    llm = OpenAIChat(streaming=True, callback_manager=CallbackManager([StreamingStdOutCallbackHandler()]), verbose=True, temperature=0,\
+                    prefix_messages=prefix_messages)
     qa_chain = ChatVectorDBChain.from_llm(
         llm,
         vectorstore,