Flask SocketIO: Per client settings

Question

When multiple clients connect to my socketio flask application, how can I achieve per-client settings?

What I have:

@socketio.on('replay-start')
def replay(message):
    while True:
        if not paused:
            emit('replay', dict(data=f'private replay'))
        socketio.sleep(1)

Now if a client sends a pause event, I want only the clients loop to pause.

If I implement it like this:

@socketio.on('replay-pause')
def replay_pause(message):
    global paused
    paused = True

Of course this pauses all loops, and not just the one of the current client. Is there some way to achieve this? Maybe there is some "context object" where I can see the id of the client sending the message?

Answer 1

The most convenient way to store per-client settings is to use the Flask user session, which does work (with certain limitations) on Socket.IO handlers:

from flask import Flask, render_template, request, session

@socketio.on('replay-start')
def replay(message):
    while True:
        if not session.get('paused'):
            emit('replay', dict(data=f'private replay'))
        socketio.sleep(1)

@socketio.on('replay-pause')
def replay_pause(message):
    session['paused'] = True