Flask-socketio, emit an event to another namespace

Question

I am using Flask-socketio (http://flask-socketio.readthedocs.org/en/latest/).

I am currently getting a

KeyError: '/local'

when using this in events.py. Note the differing namespaces:

@socketio.on('connect', namespace='/photo')
def client_connect():
    emit('event', { 'type': 'client_connect' }, namespace='/local')

Using Flask-socketio is it possible to emit to a separate namespace to that which the event occurred on? The documentation seems to suggest so, but I can't workout why I keep getting the KeyError.

EDIT: Thanks @Miguel for your proposed answer, I have tried again (after a long time away from the project) but still get a keyerror with the below:

@socketio.on('connect', namespace='/local')
def local_client_connect():
    print ('Local client connected.')

@socketio.on('connect', namespace='/photo')
def client_connect():
    print ('Client connected.')
    send('client_connect', namespace='/local')

When I run the app I see the printed 'Local client connected.' and only then do I allow a client to access the /photo route. I see 'Client connected' printed and then of course the keyerror.

I have upgraded flask-socketio to 0.4.2.

Best

Andrew

did you find any solution, or figured out what to make in that case ? Thanks. — Mostafa Khattab, Feb 03 '16 at 18:31
I think I built the whole thing in node.js in the end! So I'm afraid not. — roowilliams, Feb 03 '16 at 19:00
How did you implement it in nodejs socketio ?? did the example above worked ?? — Mostafa Khattab, Feb 03 '16 at 19:01
It was a long time ago but using socket.io and I think emitting to the individual client. You can also put clients in a 'room' and broadcast to that room only. Check out the socket.io site, it has some great examples. — roowilliams, Feb 03 '16 at 19:03
Why you've chosen back to nodejs? What are all the complexities you've faced here? — Suresh, Mar 02 '21 at 07:00

Miguel Grinberg · Answer 1 · 2014-07-19T23:09:29.833

4

You need to have at least one handler on the second namespace. For example:

@socketio.on('connect', namespace='/local')
def local_client_connect():
    pass

Then Flask-SocketIO will know about /local and will be able to emit messages to it.

edited Jul 19 '14 at 23:09

answered Jul 16 '14 at 17:05

Miguel Grinberg

65,299
14
133
152

Hi @Miguel, I tried your suggestion but I am still getting a KeyError on 'local'. The handler for the second name space is declared before my original code and is also being called before it, ie. local_client_connect() happens before client_connect(). – roowilliams Jul 17 '14 at 09:07

score 4 · Answer 2 · answered Jun 03 '19 at 19:11

4

I had same problems and solved like this.

@socketio.on('connect', namespace='/photo')
def client_connect():
    socketio.emit('event', { 'type': 'client_connect' }, namespace='/local')

answered Jun 03 '19 at 19:11

nshuya

41
2

Flask-socketio, emit an event to another namespace

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