Time or event (websocket/redis) callbacks

[schaumb]

Problem

I want to create outside trigger event changes (like timeout, websocket connection, redis subscribed channel, other streamlit app) without owning the report thread, and without blocking user interactions (buttons, checkboxes etc.) and with streamlit's low code mindset

Solution

Preferred solution:

We created a solution here: https://github.com/FloWide/streamlit_callbacks

with simple usages:

from streamlit.callbacks.callbacks import later, rerun
import streamlit as st
from datetime import datetime

st.write(datetime.now())

later(2.0, rerun) # After 2 sec calls a rerun

import streamlit.callbacks.websocket as ws
import streamlit as st

print_message = st.empty()
def msg_handler(msg):
  print_message.write(f"Arrived message from ws: {msg}")

ws.on_message('ws://localhost:10000', msg_handler)

More examples at README.md

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[kmcgrady]

Hey @schaumb Thanks for the report!

That seems like a really interesting idea. Our product has a large backlog of enhancement requests to go through, but I will make note of this enhancement request for them to consider.

[randyzwitch]

Hi @schaumb -

In version 0.69, we merged a community PR from @SimonBiggs called st.experimental_rerun, which might do your first use case.

Best, Randy

[schaumb]

Hi @randyzwitch,

Thanks, I know that function exist. The callbacks rerun is for another reason. st.experimental_rerun asks runner thread for stop the code, and do it again. callbacks.rerun is runs on callbacks thread which will delegate a rerun after a condition is met, so It is made for another reason.