St.session_state not getting updated briefly (at random times)

[eldos-dl]

Summary

Below I have attached a code, which should disable the text input for 5 seconds after a value is entered. While running this code. Its working most of the time. But in the middle I am briefly getting an error. I felt, that st.session_state is not getting updated some times. Want to understand if there is any work around, or if I am using any functions in a wrong way.

Steps to reproduce

Code snippet:

import time
import streamlit as st


def disable():
    st.session_state["disabled"] = True


def enable():
    st.session_state["disabled"] = False


print("0", st.session_state)

if "disabled" not in st.session_state:
    st.session_state["disabled"] = False
    print("1", st.session_state)

print("2", st.session_state)

print("3", st.session_state)

if user_input := st.text_input(
    "Enter some text",
    disabled=st.session_state.disabled,
    on_change=disable
):
    # Do some processing with input
    time.sleep(5)
    enable()
    st.experimental_rerun()

Play-around the UI for some-time.

Expected behavior:

Text field should get disabled for 5 seconds after every onchange event.

Actual behavior:

Though that’s happening, occasionally, I am noticing the following logs. Based on the logic st.session_state should not be empty.

0 {}
1 {}
2 {}
3 {}
2023-07-21 11:43:40.192 Uncaught app exception
Traceback (most recent call last):
  File ".venv/lib/python3.10/site-packages/streamlit/runtime/state/session_state_proxy.py", line 119, in __getattr__
    return self[key]
  File ".venv/lib/python3.10/site-packages/streamlit/runtime/state/session_state_proxy.py", line 90, in __getitem__
    return get_session_state()[key]
  File ".venv/lib/python3.10/site-packages/streamlit/runtime/state/safe_session_state.py", line 111, in __getitem__
    raise KeyError(key)
KeyError: 'disabled'

Debug info

• Streamlit version: 1.24.1
• Python version: 3.10.11
• OS version: Ubuntu 22.04
• Browser version: Google Chrome Version 114.0.5735.198

Additional information

I am getting this error briefly. And it’s getting resolved automatically after some time. But when I am trying to use this type of logic in a larger application, its running into some complex errors

[dataprofessor]

Hi @eldos-dl

Here are some related forum posts on why session states may not refresh (essentially when the app refreshes the session state also starts over).

Why session state is not persisting between refresh?

Summary I’m trying to persist the authentication token of my app in a session state, but this gets lost when the browser rerun. Steps to reproduce Apologies if the code is not exactly as the one in writing, but I’m doing this by heart. Code snippet: Main.py If 'token' is not in st.session_state: st.session_state.token = something else # use the session state value There is of course much more logic in my code, but on the browser refresh, I was expecting token to be in the state hen…

The following shows how to resolve this:

Widget updating for every second input when using session state - Streamlit Docs

Hope this helps!