How do you send messages from Flask server (Python) to HTML client?
Here's a simple example showing how to connect to the SocketIO server and receive a message from the server upon that connection.
app.py
from flask import Flask, render_template from flask_socketio import SocketIO, emit app = Flask(__name__) app.config['SECRET_KEY'] = 'secret!' socketio = SocketIO(app) @socketio.on('connect') def connect(): emit('message', {'hello': "Hello"}) @app.route('/') def index(): return render_template('index.html') if __name__ == '__main__': socketio.run(app, debug=True) templates/index.html
<head> <script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/socket.io/1.3.6/socket.io.min.js"></script> <script type="text/javascript" charset="utf-8"> var socket = io.connect('http://' + document.domain + ':' + location.port); socket.on('connect', function() { console.log('connected'); }); socket.on('message', function(data) { console.log(data); }); </script></head>Edit:
To have the server send a socketio message every five seconds, you can use a background thread:
app.py
from flask import Flask, render_template from flask_socketio import SocketIO, emit import time app = Flask(__name__) app.config['SECRET_KEY'] = 'secret!' socketio = SocketIO(app) thread = None def background_thread(): while True: socketio.emit('message', {'goodbye': "Goodbye"}) time.sleep(5) @socketio.on('connect') def connect(): global thread if thread is None: thread = socketio.start_background_task(target=background_thread) @app.route('/') def index(): return render_template('index.html') if __name__ == '__main__': socketio.run(app, debug=True)