如何通过非异步方法发送网络套接字消息？

编程问答 2022-06-03

问题描述

我正在使用these docs来从Python了解websockets。

当所有在async方法内部发生的事情都可以正常工作，但是我该如何发送消息呢？在我的特定示例中，我从RaspBerry PI的GPIO引脚上收到一个button_pressed事件，我想向所有连接的用户发送该按钮被按下的消息：

import asyncio
import websockets
import gpiozero

USERS = set()

def button_pressed():
    print("Doorbell rang!")
    if USERS:
        for user in USERS:
            print(f"Sending ring to {user}")
            asyncio.wait(user.send("ring"))

button = gpiozero.Button(3)
button.when_pressed = button_pressed

def register(ws):
    USERS.add(ws)

def unregister(ws):
    USERS.remove(ws)

async def doorbellsocket(websocket,path):
    register(websocket)

    try:
        async for message in websocket:
            print(f"Received message: {message}. Ignored.")
    finally:
        unregister(websocket)
    
print(f"Starting doorbellserv on {settings.host}:{settings.port}")
start_server = websockets.serve(doorbellsocket,settings.host,settings.port)
asyncio.get_event_loop().run_until_complete(start_server)
asyncio.get_event_loop().run_forever()

代码运行，按钮按下事件被触发，Python说它发送了一些东西，但是没有任何内容到达我的客户端，就像这样简单：

function connectToServ() {
    var socket = new WebSocket(url);
    console.log("Connected to "+socket)
    socket.onmessage = function(event) {
        console.log(event.data);
    }; 
}

解决方法

我必须这样做asyncio.run：

def button_pressed():
    print("Doorbell rang!")

    if USERS:
        for user in USERS:
            print(f"Sending ring to {user}")
            asyncio.run(user.send("ring"))
gpiozeropythonwebsocketwebsocketwebsocket