Persist memory and answer

[Erica]

Summary

Hi, I want to make a q and q app using Streamlit.

Steps to reproduce

Code snippet:

import streamlit as st
import random
import time

st.title("Simple chat")

# Initialize chat history
if "messages" not in st.session_state:
    st.session_state.messages = []

# Display chat messages from history on app rerun
for message in st.session_state.messages:
    with st.chat_message(message["role"]):
        st.markdown(message["content"])

# Accept user input
if prompt := st.chat_input("What is up?"):
    # Add user message to chat history
    st.session_state.messages.append({"role": "user", "content": prompt})
    # Display user message in chat message container
    with st.chat_message("user"):
        st.markdown(prompt)

    # Display assistant response in chat message container
    with st.chat_message("assistant"):
        message_placeholder = st.empty()
        full_response = ""
        assistant_response = random.choice(
            [
                "Hello there! How can I assist you today?",
                "Hi, human! Is there anything I can help you with?",
                "Do you need help?",
            ]
        )
        # Simulate stream of response with milliseconds delay
        for chunk in assistant_response.split():
            full_response += chunk + " "
            time.sleep(0.05)
            # Add a blinking cursor to simulate typing
            message_placeholder.markdown(full_response + "▌")
        message_placeholder.markdown(full_response)
    # Add assistant response to chat history
    st.session_state.messages.append({"role": "assistant", "content": full_response})

If applicable, please provide the steps we should take to reproduce the error or specified behavior.

Expected behavior:

The questions and answers should be preserved if I refresh the page. Also if I refresh the page while an answer is being generated, the chat box should be blocked so I have to wait until the current answer is generated.

Actual behavior:

Just the opposite of the expected behaviour

[tonykip]

Hi @Erica,

Thanks for posting! So st.session_state is designed to maintain the state across reruns of the app within the same browser session. When you refresh the app, it starts a new session and that’s why the content refreshes as well. There’s no browser/cookie-based storage yet. Also, if you refresh while the assistant is “typing,” the message won’t complete since the state has been reset.

You can consider connecting to a database and saving the responses and prompts there then calling them upon refreshes.

Let me know if this helps.

[mannacharya]

1. Session State always resets on page refresh. You will need to use a simple database to store the resoponses.
2. Behavior of blocking further chat when one response / continuing on response is kinda complex.

Implementing on @tonykip 's explanation:
I have used tinydb here. (do pip install tinydb to resolve missing dependency)

import streamlit as st
import random
import time
from tinydb import TinyDB

# Initialize chat history
db = TinyDB('chat_history.json')

st.title("Simple chat")

# Initialize chat history from previous sessions
chat_history = db.all()

# Display chat messages from history on app rerun
for message in chat_history:
    with st.chat_message(message["role"]):
        st.markdown(message["content"])

# Disable text input when assistant is responding
if "disabled" not in st.session_state:
    st.session_state["disabled"] = False

# Toggle disabled state
def disable_toggle():
    st.session_state["disabled"] = not(st.session_state["disabled"])

# Button to to test disable
if st.button('toggle'):
    disable_toggle()

# Accept user input if assistant is not responding
# if not st.session_state.disabled:  # Check if the text input is not disabled
prompt = st.chat_input("What is up?", disabled=st.session_state["disabled"])

if prompt:
    # Add user message to chat history
    user_message = {"role": "user", "content": prompt}
    chat_history.append(user_message)
    db.insert(user_message)

    # Display user message in chat message container
    with st.chat_message("user"):
        st.markdown(prompt)

    
    # Simulate assistant response
    with st.chat_message("assistant"):
        message_placeholder = st.empty()
        full_response = ""
        assistant_response = random.choice([
            "Hello there! How can I assist you today?",
            "Hi, human! Is there anything I can help you with?",
            "Do you need help?",
        ])
        for chunk in assistant_response.split():
            full_response += chunk + " "
            time.sleep(0.05)
            # Add a blinking cursor to simulate typing
            message_placeholder.markdown(full_response + "▌")
        message_placeholder.markdown(full_response)

        # Add assistant response to chat history
        assistant_message = {"role": "assistant", "content": full_response}
        chat_history.append(assistant_message)
        db.insert(assistant_message)

# Reset chat history button
if len(db.all()) > 0:
    # Show button if Chat history not empty
    if st.button("Reset Chat"):
        # Delete all entries in Database
        db.truncate()
        # Reload Page
        st.experimental_rerun()

This will cover some of your functionalities.

[Erica]

Hi @tonykip, thanks for replying. Is there a good way to check if the page was refreshed? I could not find a function or something that is made for that sadly.

[tonykip]

There’s no specific function to check if was refreshed. The refresh is related to manually hitting the refresh/reload button on your browser which creates a new session and wipes the session state.

[Erica]

Alright, thank you very much :). This topic may be closed.

[tonykip]

Glad it is resolved! Happy Streamlit-ing!