预期的 ASGI 消息“websocket.accept”或“websocket.close”，但得到“http.response.start”

Posted 2023-02-16

【中文标题】预期的 ASGI 消息“websocket.accept”或“websocket.close”，但得到“http.response.start”

【英文标题】：Expected ASGI message 'websocket.accept' or 'websocket.close', but got 'http.response.start'

【发布时间】：2021-03-02 10:39:12

【问题描述】：

我想连接websockets，但在启动时出现错误。

uvicorn app:app --reload --ws websockets

要求

操作系统：Linux Ubuntu 20.04 LTS

Python 3.8.6

浏览器：Chrome 88.0.4324.182

fastapi==0.63.0

python-engineio==4.0.0

python-socketio==5.0.4

小星星==0.13.6

uvicorn==0.13.3

网络套接字==8.1

app.py

from typing import Optional

import socketio
from fastapi import FastAPI, Query, WebSocket


sio = socketio.AsyncServer(
    async_mode="asgi", cors_allowed_origins="*", logger=True, engineio_logger=True
)
app = FastAPI(debug=True)
app_socketio = socketio.ASGIApp(sio)
app.mount(path="/", app=app_socketio)


@app.websocket("/items/item_id/ws")
async def websocket_endpoint(
    websocket: WebSocket,
    item_id: str,
    q: Optional[int] = None,
):
    # pylint: disable=C0103,W0613
    await websocket.accept()
    while True:
        data: str = await websocket.receive_text()

反应应用

const Index: React.FC = () => 
    var ws = new WebSocket('ws://127.0.0.1:8000/items/1/ws')

追溯

Traceback (most recent call last):
  File "/home/m0nte-cr1st0/.virtualenvs/hypercube/lib/python3.8/site-packages/uvicorn/protocols/websockets/websockets_impl.py", line 157, in run_asgi
    result = await self.app(self.scope, self.asgi_receive, self.asgi_send)
  File "/home/m0nte-cr1st0/.virtualenvs/hypercube/lib/python3.8/site-packages/uvicorn/middleware/proxy_headers.py", line 45, in __call__
    return await self.app(scope, receive, send)
  File "/home/m0nte-cr1st0/.virtualenvs/hypercube/lib/python3.8/site-packages/fastapi/applications.py", line 199, in __call__
    await super().__call__(scope, receive, send)
  File "/home/m0nte-cr1st0/.virtualenvs/hypercube/lib/python3.8/site-packages/starlette/applications.py", line 111, in __call__
    await self.middleware_stack(scope, receive, send)
  File "/home/m0nte-cr1st0/.virtualenvs/hypercube/lib/python3.8/site-packages/starlette/middleware/errors.py", line 146, in __call__
    await self.app(scope, receive, send)
  File "/home/m0nte-cr1st0/.virtualenvs/hypercube/lib/python3.8/site-packages/starlette/exceptions.py", line 58, in __call__
    await self.app(scope, receive, send)
  File "/home/m0nte-cr1st0/.virtualenvs/hypercube/lib/python3.8/site-packages/starlette/routing.py", line 566, in __call__
    await route.handle(scope, receive, send)
  File "/home/m0nte-cr1st0/.virtualenvs/hypercube/lib/python3.8/site-packages/starlette/routing.py", line 376, in handle
    await self.app(scope, receive, send)
  File "/home/m0nte-cr1st0/.virtualenvs/hypercube/lib/python3.8/site-packages/engineio/async_drivers/asgi.py", line 65, in __call__
    await self.not_found(receive, send)
  File "/home/m0nte-cr1st0/.virtualenvs/hypercube/lib/python3.8/site-packages/engineio/async_drivers/asgi.py", line 110, in not_found
    await send('type': 'http.response.start',
  File "/home/m0nte-cr1st0/.virtualenvs/hypercube/lib/python3.8/site-packages/uvicorn/protocols/websockets/websockets_impl.py", line 209, in asgi_send
    raise RuntimeError(msg % message_type)
RuntimeError: Expected ASGI message 'websocket.accept' or 'websocket.close', but got 'http.response.start'.

【参考方案1】：

const Index: React.FC = () => 
var ws = new WebSocket('ws://127.0.0.1:8000/items/1/ws')

将此函数设为异步并等待并重试