[英]Using a websocket client as a class in python
I'm trying access some data using websockets, but I cannot really get around the examples given in the websockets documentation.我正在尝试使用 websockets 访问一些数据,但我无法真正绕过 websockets 文档中给出的示例。
I have this code ( https://pypi.org/project/websocket_client/ ) and want to transform it into a class.我有这个代码( https://pypi.org/project/websocket_client/ )并想将它转换成一个类。
import websocket
import thread
import time
def on_message(ws, message):
print message
def on_error(ws, error):
print error
def on_close(ws):
print "### closed ###"
def on_open(ws):
def run(*args):
for i in range(3):
time.sleep(1)
ws.send("Hello %d" % i)
time.sleep(1)
ws.close()
print "thread terminating..."
thread.start_new_thread(run, ())
if __name__ == "__main__":
websocket.enableTrace(True)
ws = websocket.WebSocketApp("ws://echo.websocket.org/",
on_message = on_message,
on_error = on_error,
on_close = on_close)
ws.on_open = on_open
ws.run_forever()
The idea is to have this all websocket functionality in a class so that I can just create an object of that class.这个想法是在一个类中拥有所有这些 websocket 功能,这样我就可以创建该类的一个对象。
I tried to start doing it but I cannot even get passed this:我试图开始这样做,但我什至无法通过这个:
class MySocket(object):
def __init__(self):
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 on_message(ws, message):
print message
def on_error(ws, error):
print error
def on_close(ws):
print "### closed ###"
def on_open(ws):
ws.send("Hello %d" % i)
The error starts right away in on_message
saying that's an "unresolved reference".错误立即在on_message
开始,说这是一个“未解析的引用”。
Package the call inside an anonymous lambda
function to achieve a proper call with the correct self
:将调用打包在匿名lambda
函数中,以使用正确的self
实现正确调用:
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)
...
The WebSocketApp
needs callable objects for its callbacks (both the ones you pass in the constructor, like on_message
, and the one you're setting after the fact, on_open
). WebSocketApp
的回调需要可调用对象(您在构造函数中传递的对象,如on_message
,以及事后设置的对象, on_open
)。
Plain functions are callable objects, so your non-OO version works fine, because you're passing the plain functions.普通函数是可调用对象,因此您的非 OO 版本可以正常工作,因为您正在传递普通函数。
Bound methods are also callable objects.绑定方法也是可调用对象。 But your OO version isn't passing bound methods.但是您的 OO 版本没有传递绑定方法。 A bound method is, as the name implies, bound to an object.绑定方法,顾名思义,绑定到一个对象。 You do this by using the obj.method
notation.您可以使用obj.method
表示法来完成此操作。 In your case, that's self.on_message
:在你的情况下,那是self.on_message
:
self.ws = websocket.WebSocketApp("ws://echo.websocket.org/",
on_message = self.on_message,
on_error = self.on_error,
on_close = self.on_close)
self.ws.on_open = self.on_open
However, you've got another problem.但是,您还有另一个问题。 While this will make your error go away, it won't make your code actually work.虽然这会使您的错误消失,但不会使您的代码真正工作。 A normal method has to take self
as its first argument:一个普通的方法必须将self
作为它的第一个参数:
def on_message(self, ws, message):
print message
It's also worth noting that you're not really using the class for anything.另外值得一提的是,你没有真正使用类的东西。 If you never access anything off self
, the class is just acting like a namespace.如果您从不访问self
任何内容,则该类就像一个命名空间。 Not that this is always a bad thing, but it's usually a sign that you need to at least think through your design.并不是说这总是一件坏事,但这通常表明您至少需要仔细考虑您的设计。 Is there really any state that you need to maintain?真的有任何需要维护的状态吗? If not, why do you want a class in the first place?如果没有,你为什么首先要上课?
You may want to reread the tutorial section on Classes to understand about methods, self
, etc.您可能需要重新阅读有关类的教程部分以了解方法、 self
等。
import websocket
try:
import thread
except ImportError:
import _thread as thread
import time
class OnyxGenericClient:
"""
Onyx Client Interface
"""
def __init__(self, ):
websocket.enableTrace(True)
ws = websocket.WebSocketApp("ws://localhost:3000/",
on_message=self.on_message,
on_error=self.on_error,
on_close=self.on_close)
self.ws = ws
self.ws.on_open = self.on_open
self.ws.run_forever()
# def initiate(self):
def on_message(self, message):
print(message)
return message
def on_error(self, error):
return error
def on_close(self):
print("### closed ###")
def run(self, *args):
global driver
driver = True
while driver:
try:
time.sleep(1)
print("Say something nice")
p = input()
self.ws.send(p)
except KeyboardInterrupt:
driver = False
time.sleep(1)
self.ws.close()
print("thread terminating...")
def on_open(self):
thread.start_new_thread(self.run, ())
if __name__ == "__main__":
websocket.enableTrace(True)
onyx_client = OnyxGenericClient()
I wonder why everyone is still putting the ws
parameter.不知道为什么大家还在放ws
参数。
Read the error log.阅读错误日志。
File "venv/lib/python3.7/site-packages/websocket/_app.py", line 343, in _callback callback(*args)文件“venv/lib/python3.7/site-packages/websocket/_app.py”,第 343 行,在 _callback 回调(*args)中
def _callback(self, callback, *args):
if callback:
try:
if inspect.ismethod(callback):
callback(*args)
else:
callback(self, *args)
except Exception as e:
_logging.error("error from callback {}: {}".format(callback, e))
if _logging.isEnabledForDebug():
_, _, tb = sys.exc_info()
traceback.print_tb(tb)
Looking at our callbacks, on_open(self, ws)
查看我们的回调, on_open(self, ws)
When the try
block executes it checks if our callback is a method or a function.当try
块执行时,它会检查我们的回调是一个方法还是一个函数。 if it is a method it would execute the callback(*args)
already our self from our CustomClient
is already passed as an argument in (*args).如果它是一个方法,它将执行callback(*args)
已经我们的自定义客户端中的CustomClient
已经作为参数传递给 (*args)。 Mind you it already has its own self
in def _callback(self, callback, *args)
.请注意,它已经在def _callback(self, callback, *args)
拥有自己的self
。 Hence, every callback that is an instance of your CustomClient
should not have the ws argument.因此,作为CustomClient
实例的每个回调CustomClient
应该有 ws 参数。
You need to add "self" to you class methods:您需要在类方法中添加“self”:
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)
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 . Self 将这些方法作为类方法,得到这个作为 on_error/message/close 方法签名将得到满足,如果由 self 调用将引用类本身。
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()
Just updating the code written by other authors on this page, that worked for me.只需更新此页面上其他作者编写的代码,这对我有用。 The problem is that in the event callback functions definition like on_message we should not use ws as parameter.问题是在像 on_message 这样的事件回调函数定义中,我们不应该使用 ws 作为参数。 self takes care of it and in the body of these event handler functions we should use self.ws self 负责它,在这些事件处理函数的主体中,我们应该使用 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")
I would like try this way:我想试试这种方式:
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
).在方法__init__(self)
使用内部函数可以避免on_message(self, ws, message)
方法的参数数量与WebSocketApp
提供给其参数on_message
的数量不匹配的on_message
(类方法多了一个参数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.我上面有一个handler
来处理消息,如果有的话,方法close(self)
来清理一些资源, run_forever(self)
来运行 websocket。
This is working:这是有效的:
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但你无权访问 self
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