app.py

import streamlit as st 

from langchain_community.chat_models import ChatOpenAI
from langchain.schema import (AIMessage, HumanMessage, SystemMessage)

def load_answer(question):
    st.session_state.sessionMessages.append(HumanMessage(content=question))
    chat = ChatOpenAI(model="gpt-3.5-turbo",temperature=0)
    answer = chat(st.session_state.sessionMessages)
    st.session_state.sessionMessages.append(AIMessage(answer.content))
    return answer.content

def get_text():
    return st.text_input("You: ", key="input")

st.set_page_config(page_title="Chat App", page_icon="🤖")
st.header("Hey, nice to meet you! How can I help you today?")

if "sessionMessages" not in st.session_state:
    st.session_state.sessionMessages = [
        SystemMessage(content="You are an assistant")
    ]

user_input = get_text()

submit = st.button('Generate')

if submit:
    st.subheader("Answer:")
    response = load_answer(user_input)
    st.write(response)