WebSocket events handling in Flask - Mini Project: Build & Apply

WebSocket Events Handling with Flask

📖 Scenario: You are building a simple chat server using Flask and WebSocket. Users will connect to the server, send messages, and receive messages from others in real-time.

🎯 Goal: Build a Flask app that handles WebSocket events: connection, message reception, and disconnection.

📋 What You'll Learn

Create a Flask app with Flask-SocketIO

Handle client connection event

Handle client message event

Handle client disconnection event

💡 Why This Matters

🌍 Real World

WebSocket event handling is essential for real-time web apps like chat apps, live notifications, and multiplayer games.

💼 Career

Understanding WebSocket events and Flask-SocketIO is valuable for backend developers working on interactive web applications.

1

Set up Flask app and SocketIO

Import Flask and SocketIO from flask_socketio. Create a Flask app called app and initialize SocketIO with app as socketio.

Flask

# Your code here

Need a hint?

Use Flask(__name__) to create the app and pass it to SocketIO.

2

Add event handler for client connection

Use the @socketio.on('connect') decorator to create a function called handle_connect that runs when a client connects.

Flask

from flask import Flask
from flask_socketio import SocketIO

app = Flask(__name__)
socketio = SocketIO(app)

# Your code here

Need a hint?

Use @socketio.on('connect') above a function named handle_connect.

3

Add event handler for receiving messages

Use the @socketio.on('message') decorator to create a function called handle_message that takes a parameter msg and passes (does nothing) inside.

Flask

from flask import Flask
from flask_socketio import SocketIO

app = Flask(__name__)
socketio = SocketIO(app)

@socketio.on('connect')
def handle_connect():
    pass

# Your code here

Need a hint?

Use @socketio.on('message') and define handle_message(msg).

4

Add event handler for client disconnection

Use the @socketio.on('disconnect') decorator to create a function called handle_disconnect that runs when a client disconnects and passes inside.

Flask

from flask import Flask
from flask_socketio import SocketIO

app = Flask(__name__)
socketio = SocketIO(app)

@socketio.on('connect')
def handle_connect():
    pass

@socketio.on('message')
def handle_message(msg):
    pass

# Your code here

Need a hint?

Use @socketio.on('disconnect') and define handle_disconnect().