使用Web套接字内部的同步功能来执行starlette

问题描述

我正在尝试使用starlette构建一个Web套接字，该消息接收消息，在同步函数中运行计算并返回响应。

@app.websocket("/ws")
async def websocket_endpoint(websocket: WebSocket):
    await websocket.accept()
    while True:
        stock = await websocket.receive_text()
        stock = stock.upper()
        data = sentiment_analysis(stock=stock)
        await websocket.send_json({"score": data})

情感分析是一个同步功能。

因此接收到文本并运行计算，并且如果我打印数据变量（字典），我会看到它已正确返回，但是当我尝试将其发送回客户端时，出现以下错误：

ERROR:    Exception in Asgi application
Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/uvicorn/protocols/websockets/websockets_impl.py",line 153,in run_asgi
    result = await self.app(self.scope,self.asgi_receive,self.asgi_send)
  File "/usr/lib/python3/dist-packages/uvicorn/middleware/proxy_headers.py",line 45,in __call__
    return await self.app(scope,receive,send)
  File "/usr/local/lib/python3.8/dist-packages/fastapi/applications.py",line 179,in __call__
    await super().__call__(scope,send)
  File "/usr/local/lib/python3.8/dist-packages/starlette/applications.py",line 111,in __call__
    await self.middleware_stack(scope,send)
  File "/usr/local/lib/python3.8/dist-packages/starlette/middleware/errors.py",line 146,in __call__
    await self.app(scope,send)
  File "/usr/local/lib/python3.8/dist-packages/starlette/exceptions.py",line 58,send)
  File "/usr/local/lib/python3.8/dist-packages/starlette/routing.py",line 566,in __call__
    await route.handle(scope,line 283,in handle
    await self.app(scope,line 57,in app
    await func(session)
  File "/usr/local/lib/python3.8/dist-packages/fastapi/routing.py",line 228,in app
    await dependant.call(**values)
  File "./app.py",line 13,in websocket_endpoint
    stock = await websocket.receive_text()
  File "/usr/local/lib/python3.8/dist-packages/starlette/websockets.py",line 85,in receive_text
    self._raise_on_disconnect(message)
  File "/usr/local/lib/python3.8/dist-packages/starlette/websockets.py",line 80,in _raise_on_disconnect
    raise WebSocketdisconnect(message["code"])
starlette.websockets.WebSocketdisconnect: 1011  

解决方法

当客户端关闭连接时，您需要处理 WebSocketDisconnect 异常。它可以是这样的：

@app.websocket("/ws")
async def websocket_endpoint(websocket: WebSocket):
    await websocket.accept()
    try:
        while True:
            stock = await websocket.receive_text()
            stock = stock.upper()
            data = sentiment_analysis(stock=stock)
            await websocket.send_json({"score": data})
    except WebSocketDisconnect:
        handle_exception()
        ...
    else:
        await websocket.close()