Building a Flask chat app with flask-socketio

Flask is a popular web framework for Python that is used to build web applications. Flask-socketio is an extension for Flask that adds support for handling WebSocket connections, which can be used to build real-time web applications such as chat apps.

In this article, we will walk through the process of building a simple chat app with Flask and flask-socketio. We will use HTML, CSS, and JavaScript for the front-end, and Flask and flask-socketio for the back-end.

Setting up the project

First, we need to create a new Flask project and install the flask-socketio library. You can do this by running the following commands in your terminal:

“`bash
$ mkdir flask-chat-app
$ cd flask-chat-app
$ pip install flask flask-socketio
“`

Next, create a new file called app.py and add the following code:

“`python
from flask import Flask, render_template
from flask_socketio import SocketIO

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

@app.route(‘/’)
def index():
return render_template(‘index.html’)

if __name__ == ‘__main__’:
socketio.run(app, debug=True)
“`

This code sets up a basic Flask app with a route for the home page that renders the index.html template.

Creating the front-end

Now, let’s create the front-end for our chat app. Create a new file called index.html in the templates folder and add the following code:

“`html

/* Add some styles for the chat interface */

Send

// Add JavaScript code to handle the WebSocket connection and send messages

“`

This code sets up the basic structure for our chat app interface, including a form for sending messages and a container for displaying the chat history.

Handling WebSocket connections

Finally, let’s add the code to handle WebSocket connections on the server side. Update the app.py file with the following code:

“`python
from flask import Flask, render_template
from flask_socketio import SocketIO

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

@app.route(‘/’)
def index():
return render_template(‘index.html’)

@socketio.on(‘message’)
def handle_message(message):
print(‘received message: ‘ + message)
send(message, broadcast=True)

if __name__ == ‘__main__’:
socketio.run(app, debug=True)
“`

This code creates a socketio.on event handler for incoming messages, which will print the message to the console and broadcast it to all connected clients.

That’s it! With this code, you now have a basic Flask chat app with flask-socketio. You can build on this foundation to add features such as user authentication, message history, and more.