Python Streamlit chat memory

August 29, 2023

I am trying to make an interface using Streamlit, but when the I refresh the page using ctrl + r or the round arrow from top left corner of chrome, the previous chat is no longer there.

import streamlit as st

st.title("Echo Bot")

if "messages" not in st.session_state:
    st.session_state.messages = []

for message in st.session_state.messages:
    with st.chat_message(message["role"]):
        st.markdown(message["content"])

if prompt := st.chat_input("What is up?"):
    st.chat_message("user").markdown(prompt)
    st.session_state.messages.append({"role": "user", "content": prompt})
    response = f"Echo: {prompt}"

    with st.chat_message("assistant"):
        st.markdown(response)

    st.session_state.messages.append({"role": "assistant", "content": response})

>Solution :

Seems to work using the decorator @st.cache_resource (it replaces the deprecated @st.experimental_singleton)

import streamlit as st

st.title("Echo Bot")

@st.cache_resource
def get_messages():
    if "messages" not in st.session_state:
        st.session_state.messages = []
    return st.session_state.messages


st.session_state.messages = get_messages()


for message in st.session_state.messages:
    with st.chat_message(message["role"]):
        st.markdown(message["content"])

if prompt := st.chat_input("What is up?"):
    st.chat_message("user").markdown(prompt)
    st.session_state.messages.append({"role": "user", "content": prompt})
    response = f"Echo: {prompt}"

    with st.chat_message("assistant"):
        st.markdown(response)

    st.session_state.messages.append({"role": "assistant", "content": response})