I am playing around with websockets in order to see if I can replace polling updates to a project. I am using Flask-Sockets and I want to emit an update through a Flask view.
For example
from flask import Flask
from flask_sockets import Sockets
app = Flask(__name__)
sockets = Sockets(app)
@sockets.route('/echo')
def echo_socket(ws):
while True:
message = ws.receive()
ws.send(message)
@app.route('/')
def hello():
# here I want to emit a message like ws.send(message)
return 'Hello World!'
I looked around and I didnt find anything similar. Is this thing possible?
THIS IS VERY VERY SIMPLE DEMO EXAMPLE
In the below example, on every 2 seconds, the server send message to the client with updated count. First parameter of emit function tells which function to call on client side.
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)
thread = None
def background_thread():
count = 0
while True:
socketio.sleep(2)
count += 1
socketio.emit('my_response',
{'data': 'Message from server', 'count': count},
namespace='/test')
@app.route('/')
def index():
return render_template('index.html')
@socketio.on('connect', namespace='/test')
def test_connect():
global thread
if thread is None:
thread = socketio.start_background_task(target=background_thread)
emit('my_response', {'data': 'Connected', 'count': 0})
if __name__ == '__main__':
socketio.run(app, debug=True, host='0.0.0.0', port=5050)
On your client side you will have to use this. In this example I have included CDN. Similarly for demo purpose I have used jquery.
templates/index.html
<!DOCTYPE HTML>
<html>
<head>
<title>Flask-SocketIO Test</title>
<script type="text/javascript" src="//code.jquery.com/jquery-1.4.2.min.js"></script>
<script type="text/javascript" src="//cdnjs.cloudflare.com/ajax/libs/socket.io/1.3.5/socket.io.min.js"></script>
<script type="text/javascript" charset="utf-8">
$(document).ready(function() {
namespace = '/test';
var socket = io.connect(location.protocol + '//' + document.domain + ':' + location.port + namespace);
// This will be called by server.
// Anonymous function will be executed and span with id "view" will be updated
socket.on('my_response', function(msg) {
$('span#view').text(msg.count);
});
});
</script>
</head>
<body>
<h1>Flask-SocketIO Simple Example</h1>
<p>Counter at server: <span id="view"></span></p>
</a>
</body>
</html>
When you run this using python app.py
, and visit http://127.0.0.1:5050, then you should see the sockets in action.
A working version of the demo is available here