Flask socket IO emit from another module

Question

I have almost read every piece of article available on the internet but nothing seems to work for my case. I have installed flask-socketio and everything works fine until I emit the messages from a module other than app.py.

I have tried several ways to accomplish this and I have also read in the doc about it by using Redis but it also did not work for me. Here are the code snippets that I have.

app.py

from flask import Flask
from flask import request
from flask_socketio import send, SocketIO, emit, join_room

app = Flask(__name__)

# This is to stop force sorting in response, by default jsonify sorts the response keys alphabetically
app.config["JSON_SORT_KEYS"] = False

socketio = SocketIO(app, cors_allowed_origins="*")

@socketio.on('join')
def client_join_room(data):
    print(type(data))
    room = data['room']
    join_room(room)
    send('you have entered the room.', room=room)


@app.route('/msg')
def send_message():
    socketio.emit("message", "Server message", room='my_room')
    return "I got you."



if __name__ == '__main__':
    socketio.run(host="0.0.0.0", port=5001, debug=True, app=app)

my_module.py

def some_method():
    import app
    app.socketio.emit("message", "Some information about process", room='my_room', broadcast=True)

Note that I have imported app inside the method because app.py also imports my_module.py

I am able to join room.
When I call localhost:5001/msg it does emit to 'my_room'.
The emit does not work inside my_module.py and I have no idea why.

I am consoling the messages that I get from the server at the front-end so I know for sure which messages are received and which are not.

Also, the some_method() here is called by an API request from app.py. Just in case if that is relevant.

I have made logger=True and then I get this message printed on the terminal for each emit call. Even with the one inside some_method()

emitting event "message" to my_room [/]

Does that mean message is actually sent? If yes, then why am I not getting it in the jquery at front-end.

This is what I am doing in html page

$(document).ready(function () {
        // start up the SocketIO connection to the server
        var socket = io.connect('http://localhost:5001/');
        // this is a callback that triggers when the "message" event is emitted by the server.

        socket.on('message', function(msg){
            console.log(msg)
        });

            socket.emit('join', {room: 'my_room'});
    });

Did you enable logging on the client to see if the message is received? Clearly your server logging appears to indicate messages are getting sent, correct? — Miguel Grinberg, Dec 16 '19 at 00:03
yes, I have added client-side code that logs message in console — Manali Kagathara, Dec 16 '19 at 07:09
I think this has to do something flask being a blocking event does not allow sockets to emit messages until a request is completed. — Eternal, Dec 16 '19 at 10:55
@ManaliKagathara I mean logging on the Socket.IO client, not your application. If the server sent the message, then the client must have received it and decided to not invoke your handler, for some reason. — Miguel Grinberg, Dec 16 '19 at 12:00
The jquery code I have written here is all I have at the client side for now. Am I missing something obvious? @Miguel — Manali Kagathara, Dec 17 '19 at 06:52
Well, yes, as I said, you can enable logging on the Socket.IO client. See https://socket.io/docs/logging-and-debugging/. — Miguel Grinberg, Dec 17 '19 at 07:56

score 3 · Accepted Answer · answered Dec 26 '19 at 10:04

Please try and install Redis and eventlet for asynchronous calls and to send messages from other modules. As described in the documentation then you can change your line in app.py to

socketio = SocketIO(app, cors_allowed_origins="*", message_queue='redis://', async_mode='eventlet')

Flask socket IO emit from another module

1 Answers1