change api key handling

app.py

@@ -11,14 +11,13 @@ HumanMessagePromptTemplate,
 from langchain.memory import ConversationBufferWindowMemory
 from langchain.memory.chat_message_histories import StreamlitChatMessageHistory
 from langchain.schema import AIMessage, HumanMessage
+from openai.error import AuthenticationError
 import streamlit as st
 
 
-
-
-@st.cache_resource
-def set_api_key(api_key):
-    os.environ["OPENAI_API_KEY"] = api_key
+def set_api_key(USER_API_KEY):
+    os.environ["OPENAI_API_KEY"] = str(USER_API_KEY)
+    st.cache_resource.clear()  # clear existing chains with old api key
 
 
 @st.cache_resource
@@ -58,8 +57,10 @@ if __name__ == "__main__":
         st.write("To keep input lengths down and costs reasonable,"
                  " this bot only 'remembers' the past three turns of conversation.")
         st.write("To clear all memory and start fresh, click 'Clear history'" )
-        
-    API_KEY = st.sidebar.text_input(
+
+    st.sidebar.title("Enter API key and model")
+
+    USER_API_KEY = st.sidebar.text_input(
         'API Key',
         type='password',
         help="Enter your OpenAI API key to use this app",
@@ -79,29 +80,30 @@ if __name__ == "__main__":
         value=0.9,
         help="Set the decoding temperature. Lower temperatures give more predictable outputs."
         )
-    
-    if API_KEY is not None:
-        set_api_key(API_KEY)
+
+        
+    if USER_API_KEY is not None:
+        set_api_key(USER_API_KEY)
         memory = setup_memory()
         chain = get_chain(model_name, memory, temperature)
         if st.button("Clear history"):
             chain.memory.clear()
             st.cache_resource.clear()
-        for message in chain.memory.buffer:
+        for message in chain.memory.buffer:    # display chat history
             st.chat_message(message.type).write(message.content)
         text = st.chat_input()
         if text:
             with st.chat_message("user"):
                 st.write(text)
-            result = chain.predict(input=text)
-            with st.chat_message("assistant"):
-                st.write(result)
+            try:
+                result = chain.predict(input=text)
+                with st.chat_message("assistant"):
+                    st.write(result)
+            except AuthenticationError:
+                st.warning("Enter a valid OpenAI API key", icon="⚠️")
 
 
 
-
-
-