Update app.py

app.py

@@ -1,38 +1,60 @@
-# import streamlit as st
+#
 import streamlit as st
 
 # import openai from langchain_openai
-from langchain_openai import OpenAI
+from langchain_openai import ChatOpenAI
+
+# import HumanMessage,SystemMessage and AIMessage from the 'schema' module of the 'langchain' library.
+from langchain.schema import (
+    AIMessage,
+    HumanMessage,
+    SystemMessage
+)
+
+# From here down is all the StreamLit UI
+st.set_page_config(page_title="LangChain Demo", page_icon=":robot:")
+st.header("Hey, I'm your Chat GPT")
+
+
+# If "sessionMessages" not in st.session_state, then create a list of SystemMessage
+if "sessionMessages" not in st.session_state:
+     st.session_state.sessionMessages = [
+        SystemMessage(content="You are a helpful assistant.")
+    ]
+
 
-# Function to return the response
 def load_answer(question):
-    llm = OpenAI(model_name="gpt-3.5-turbo-instruct",temperature=0)
+    # Append the question to the sessionMessages list
+    st.session_state.sessionMessages.append(HumanMessage(content=question))
 
-    answer=llm.invoke(question)
-    return answer
+    # Invoke the chat with the sessionMessages list
+    assistant_answer  = chat.invoke(st.session_state.sessionMessages )
+
+    # Append the assistant's answer to the sessionMessages list
+    st.session_state.sessionMessages.append(AIMessage(content=assistant_answer.content))
+
+    # Return the assistant's answer
+    return assistant_answer.content
 
-# App UI starts here
-st.set_page_config(page_title="LangChain Demo", page_icon=":robot:")
-st.header("LangChain Demo")
 
-# Gets the user input
 def get_text():
-    # Add key to text_input to avoid re-rendering
-    input_text = st.text_input("User: ", key="input")
+
+    # Get the user input
+    input_text = st.text_input("You: ")
     return input_text
 
+# Initialize the ChatOpenAI object
+chat = ChatOpenAI(temperature=0)
+
 # Get user input
 user_input=get_text()
 
-# Get response
-response = load_answer(user_input)
-
 # Add button to generate response
-submit = st.button('Generate')
+submit = st.button('Generate')  
 
-# If generate button is clicked
 if submit:
-
+    # Get response from the user input and display it
+    response = load_answer(user_input)
     st.subheader("Answer:")
 
     st.write(response)