Broadcast to all connected clients except sender with python flask socketio

Question

I am following Alex Hadik's Flask Socketio tutorial which builds a very simple flask chat app.

http://www.alexhadik.com/blog/2015/1/29/using-socketio-with-python-and-flask-on-heroku

I would like to broadcast a message to all connected users except the sender. I have gone through the flasksocketio init.py but I'm still not sure how to do this.

Here's the server code.

from flask import Flask, render_template,request
from flask.ext.socketio import SocketIO,emit,send
import json,sys

app = Flask(__name__)
socketio = SocketIO(app)
clients = {}
@app.route("/")
def index():
    return render_template('index.html',)

@socketio.on('send_message')
def handle_source(json_data):
    text = json_data['message'].encode('ascii', 'ignore')
    current_client = request.namespace
    current_client_id = request.namespace.socket.sessid
    update_client_list(current_client,current_client_id)
    if clients.keys():
        for client in clients.keys():
            if not current_client_id in client:
                clients[client].socketio.emit('echo', {'echo': 'Server Says: '+text})       

def update_client_list(current_client,current_client_id):
    if not current_client_id in clients: clients[current_client_id] = current_client
    return 

if __name__ == "__main__":
    socketio.run(app,debug = False)

It's currently just broadcasting to all connected clients. I created a connected clients dict (clients) which stores the request.namespace indexed by the client id. Calling clients[client].socketio.emit() for all clients except the sending client still results in the message being broadcast to call users.

Does anyone have any thoughts on how I can broadcast messages to all connected users except the sender?

Answer 1

You don't have to save users ids and manage individual emissions, you can specify a broadcast without the sender with emit('my_event', {data:my_data}, broadcast=True, include_self=False). In your case it would be something like this:

@socketio.on('send_message')
    def handle_source(json_data):
        text = json_data['message'].encode('ascii', 'ignore')
        emit('echo', {'echo': 'Server Says: '+text}, broadcast=True, include_self=False)

If you have to send messages for a specific group of clients you can create rooms and then use emit('my_event', {data:my_data}, room=my_room, include_self=False) for sending messages to clients who joined my_room. You can check the reference of flask_socketio.emit for more details.