Using a websocket client as a class in python

Question

I\'m trying access some data using websockets, but I cannot really get around the examples given in the websockets documentation.

I have this code (https://pypi.org/proj

Answer 1

Just updating the code written by other authors on this page, that worked for me. The problem is that in the event callback functions definition like on_message we should not use ws as parameter. self takes care of it and in the body of these event handler functions we should use self.ws

class MySocket(object):
    def __init__(self):
        websocket.enableTrace(True)
        self.ws = websocket.WebSocketApp("ws://echo.websocket.org:12300/foo",
                                on_message = self.on_message,
                                on_error = self.on_error,
                                on_close = self.on_close)

    
    def on_message(self, message):
        # if you want to send something use like this
        # self.ws.send()
        print message

    def on_error(self, error):
        print error

    def on_close(self):
        print "### closed ###"

    def on_open(self):
        self.ws.send("Hello Message")

Answer 2

Package the call inside an anonymous lambda function to achieve a proper call with the correct self:

class Client:
    def __init__(self, db, symbols):
        self.ws = websocket.WebSocketApp("wss://the.server.com/api",
                    on_message = lambda ws,msg: self.on_message(ws, msg),
                    on_error   = lambda ws,msg: self.on_error(ws, msg),
                    on_close   = lambda ws:     self.on_close(ws),
                    on_open    = lambda ws:     self.on_open(ws))

    def on_message(self, ws, message):
            msg = json.loads(message)
            print(msg)
    ...

Answer 3

You need to add "self" to you class methods:

class MySocket(object):
    def __init__(self):
        websocket.enableTrace(True)
        self.ws = websocket.WebSocketApp("ws://echo.websocket.org:12300/foo",
                                on_message = self.on_message,
                                on_error = self.on_error,
                                on_close = self.on_close)

    def on_message(self, ws, message):
        print message

    def on_error(self, ws, error):
        print error

    def on_close(self, ws):
        print "### closed ###"

    def on_open(self, ws):
        ws.send("Hello %d" % i)

Answer 4

The Self makes those methods as Class methods , Got this one working as the on_error/message/close methods signature will get satisfied if called by self as will refer to the class itself .

 class MySocket(object):
   def __init__(self,x):
     websocket.enableTrace(True)
     ## Only Keep the object Initialisation here  
     self.x=x
     self.ws=None

     # call This method from a Object and it will create and run the websocket 
    def ws_comm(self):
        self.ws = websocket.WebSocketApp(self.WS_URL,on_message = 
        self.on_message,on_error =self.on_error,on_close = self.on_close)
        self.ws.on_open = self.on_open
        self.ws.run_forever()

    def on_error(self,ws, error):
        print "onError", error

    def on_close(self,ws):
       print "onClosed"

    #Send some message on open 
    def on_open(self,ws):
       self.ws.send(json.dumps(register_msg))

    def on_message(self,ws, msg):
       self.ws.send(json.dumps(msg))


 user1=Userapp('x')
 user1.ws_comm()

Answer 5

This is working:

class MySocket(object):
    def __init__(self):
        websocket.enableTrace(True)
        self.ws = websocket.WebSocketApp("ws://echo.websocket.org:12300/foo",
                                on_message = self.on_message,
                                on_error = self.on_error,
                                on_close = self.on_close)

    @staticmethod
    def on_message(ws, message):
        print message

    @staticmethod
    def on_error(ws, error):
        print error

    @staticmethod
    def on_close(ws):
        print "### closed ###"

    @staticmethod
    def on_open(ws):
        ws.send("Hello %d" % i)

But you don't have access to self

Answer 6

I would like try this way:

class FooClient(object):
    def __init__(self):
        def on_message(ws, message):
            print message
            # use 'self' variable to access other resource
            # handle message from websocket server like this
            self.handler.handle(message)

        def on_error(ws, error):
            print error

        def on_close(ws):
            print "### closed ###"

        def on_open(ws):
            ws.send("Hello %d" % i)

        # assign to 'self.handler'
        self.handler = FooHandler()
        # maybe there are another module should be initiated
        # ...

        websocket.enableTrace(True)
        self.ws = websocket.WebSocketApp("ws://echo.websocket.org:12300/foo",
                                         on_message = on_message,
                                         on_error = on_error,
                                         on_close = on_close)

    def run_forever(self):
        self.ws.run_forever()

    def close(self):
        """clean other resources"""
        pass

Using inner function in method __init__(self) could avoid the problem that the arguments number of on_message(self, ws, message) method not match with the number of WebSocketApp provides to its argument on_message (class method has one more argument self).

I have a handler above to handle the message, method close(self) to clean some resources if I have, run_forever(self) to run websocket.