How to access formData in flask sent using websockets?Flask-SocketIO

Question

How to access form data sent to Flask using web sockets? I receive invalid frame header in google chrome developer tools->console.

Extract from my javascript code:

var form_data = new FormData($('#my_form')[0]);

socket.emit('handle_form',{data:form_data});

How would I access, say 'title' field in my_form from flask ?

request.form throws the same error "Invalid frame header"

One more question, is it good to use web sockets for form submission and as an entire replacement for ajax ?

Answer 1

Instead of sending a FormData object, which is a client-side only construct, you should build a plain dictionary and send that, as all the data that is transferred back and forth in Socket.IO is serialized to JSON.

Then on the server, you will have a dict that is sent as an argument to your socket callback function. See this example for ideas on how to send form data to the server.

Answer 2

It is not like Flask-SocketIO works.

When you socket.emit something, you handle it with a callback.

@socketio.on('handle_form')
def handle_form_callback(data):
    print('received message: ' + data)

You don't have a request.form in this case.

It works as a form submission replacement, but I don't think it is a good replacement. Websockets are not stateless, they are difficulty to scale and are essentially bound to a server. Of course it has some workarounds, but it is not like the very well documented HTTP server scaling.