Python Flask Socketio BadNamespaceError while sending data to server

Question

I'm trying to send data to server from client but I get bad namespace error.

I searched for the error but didn't find any solution... Can anyone point out what mistake I've done.

server side (app.py)

from flask import Flask, render_template, request, jsonify
from flask_socketio import SocketIO

app = Flask(__name__)
socket_app = SocketIO(app)

@socket_app.on('userdata', namespace='/test')
def username(data):
    print(data)
    print(request.sid)

if __name__ == '__main__':
    socket_app.run(app, debug=True, host='127.0.0.1', port=5000)

client side(client.py)

import socketio
sio = socketio.Client(engineio_logger=True)

data = {}
data['name'] = 'Mark'

sio.connect('http://127.0.0.1:5000')
sio.emit('userdata', data , namespace='/test')
sio.wait()

error

Attempting polling connection to http://127.0.0.1:5000/socket.io/?transport=polling&EIO=4
Polling connection accepted with {'sid': '1ipsM7udDVMj0WdKAAAA', 'upgrades': ['websocket'], 'pingTimeout': 5000, 'pingInterval': 25000}
Sending packet MESSAGE data 0
Attempting WebSocket upgrade to ws://127.0.0.1:5000/socket.io/?transport=websocket&EIO=4
WebSocket upgrade was successful
Traceback (most recent call last):
  File "client.py", line 41, in <module>
    sio.emit('userdata', data , namespace='/test')
  File "/home/amit/anaconda3/envs/ANPR/lib/python3.6/site-packages/socketio/client.py", line 329, in emit
    namespace + ' is not a connected namespace.')
socketio.exceptions.BadNamespaceError: /test is not a connected namespace.
Received packet NOOP data

flask & socketio versions

python-socketio==5.0.4 python-engineio==4.0.0 Flask==1.0.2 Flask-SocketIO==5.0.1

sazerac · Accepted Answer · 2021-02-27 14:51:48Z

1

It looks like the OP figured out their own issue but when connecting to a non-default namespace you can specify it in the client connection:

sio.connect('http://127.0.0.1:5000', namespaces=['/test'])

answered Feb 27, 2021 at 14:51

sazerac

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Amit Dube · Accepted Answer · 2021-01-16 07:20:42Z

0

I got this working by having the connect handler invoked in server.

@socket_app.on('connect', namespace='/test')
def test_connect():
    print("connected")
    emit('connect_custom', {'data': 'Connected'})

which then emits to client's connect_custom handler.

@sio.on('connect_custom', namespace='/test')
def on_connect(data):
    print('client contacted by server')
    print(data)
    data = {}
    data['name'] = 'Mark'
    sio.emit('userdata', data, namespace='/test')

sio.connect('http://127.0.0.1:5000')

answered Jan 16, 2021 at 7:20

Amit Dube

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