Flask-SocketIO events in modules other than app.py-CodePudding

Flask SocketIO server implementation is not receiving client messages or event triggers when starting the Flask application (as per socketio.run(app)) using the flask command: flask run (on http://127.0.0.1:5000).

It is only outputting GET and POST polling:

127.0.0.1 - - [04/Jan/2022 13:18:26] "GET /socket.io/?EIO=4&transport=polling&t=Nub1htW HTTP/1.1" 200 -
127.0.0.1 - - [04/Jan/2022 13:18:26] "POST /socket.io/?EIO=4&transport=polling&t=Nub1i2I&sid=ELpMQjSfqpcXN731AAAA HTTP/1.1" 200 -
127.0.0.1 - - [04/Jan/2022 13:18:26] "GET /socket.io/?EIO=4&transport=polling&t=Nub1i2J&sid=ELpMQjSfqpcXN731AAAA HTTP/1.1" 200 -

Project structure:

├── Flask Web App
│   ├── app
│   │   ├── common
│   │   ├── distributed_manager
│   │   │   ├── distributed_manager.py
│   │   │   └── __init__.py
│   │   ├── __init__.py
│   │   ├── local_settings.py
│   │   ├── models
│   │   ├── settings.py
│   │   ├── static
│   │   │   ├── css
│   │   │   ├── img
│   │   │   └── js
│   │   │       ├── chat.js
│   │   │       └── responses.js
│   │   ├── templates
│   │   ├── util.py
│   │   └── views
│   │       ├── bot_views.py
│   │       ├── error_views.py
│   │       ├── __init__.py
│   │       ├── main_views.py
│   │       └── site_views.py
│   ├── flask_app.py

The app is initialised in flask_app.py by calling a function create_app() defined in app/__init__.py. This function returns a tuple containing the app object and socketio object, to be used to combine these two in the following way (in flask_app.py):

from app import create_app

app, socketio = create_app()

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

I have managed to handle messages from client by placing the event handle functions in flask_app.py in the following way:

from app import create_app

app, socketio = create_app()


@socketio.on("connect")
def handle_connection():
    print("Connected a client...")


@socketio.on("message")
def handle_message(msg):
    print("Client message: "   msg)


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

But for separation of concern reasons and to decouple the app as much as possible I would like to place the server (EDIT: handle functions of the server) in the distributed_manager.py, because later I plan to pass the messages as requests in this module.

This is my server (distributed_manager.py):

from flask_socketio import send, emit
from flask_app import socketio


def ack_client():
    print("Message was received by the client.")

@socketio.on("connect")
def handle_connection(message):
    print("connected: "   message)


@socketio.on("message")
def handle_message(message):
    print(f"Received message: {message}")

And client in chat.js:

var socket;
connectToSocket();
...
function connectToSocket(){
  socket = io.connect('http://'   document.domain   ':'   location.port);
  socket.on('connect', function() {
      socket.send('User has connected!');
  });
  // console.log("Connected to the socket.")
}

CodePudding user response：

So, I have connected my two brain cells and figured out that my distributed_manager module is executed after socketio.run(app) call and after creating the app so the @socketio.on... functions must be defined before it, specifically in my solution in app/__init__.py, which creates the app and socketio objects.