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python - 尝试使用 websockets 从 FastAPI 获取实时数据流时如何修复错误（不支持的升级请求。）？

问题描述

我如何才能获得每次迭代的响应，例如实时流源？

这是 RestAPImain.py:

from fastapi import FastAPI
from fastapi import Request
from fastapi import WebSocket
import asyncio

app = FastAPI()


@app.get("/ws_res")
async def websoc(websocket: WebSocket):
    await websocket.accept()
    for i in range(100000):
        i = "John"
        await asyncio.sleep(0.01)
        await websocket.send_json({"msg": i})
    await websocket.close()

现在，我正在尝试从 python 代码中获取响应，但我收到一条错误消息Unsupported upgrade request.

这是 API 端的输出：

INFO:     Started server process [67680]
INFO:     Waiting for application startup.
INFO:     Application startup complete.
INFO:     Uvicorn running on http://127.0.0.1:8000 (Press CTRL+C to quit)
WARNING:  Unsupported upgrade request.

这是我用来访问 API ( test.py) 的 python 代码：

import asyncio
import websockets

async def hello():
    uri = "ws://127.0.0.1:8000/ws_res"
    async with websockets.connect(uri) as websocket:
        greeting = await websocket.recv()
        print(f"< {greeting['msg']}")


asyncio.get_event_loop().run_until_complete(hello())

Traceback (most recent call last):
  File "test.py", line 12, in <module>
    asyncio.get_event_loop().run_until_complete(hello())
  File "/usr/lib/python3.8/asyncio/base_events.py", line 616, in run_until_complete
    return future.result()
  File "test.py", line 7, in hello
    async with websockets.connect(uri) as websocket:
  File "/home/test/env/lib/python3.8/site-packages/websockets/client.py", line 517, in __aenter__
    return await self
  File "/home/test/env/lib/python3.8/site-packages/websockets/client.py", line 542, in __await_impl__
    await protocol.handshake(
  File "/home/test/env/lib/python3.8/site-packages/websockets/client.py", line 296, in handshake
    raise InvalidStatusCode(status_code)
websockets.exceptions.InvalidStatusCode: server rejected WebSocket connection: HTTP 400

标签： pythonpython-3.xwebsocketfastapi

解决方案

Fastapi websocket 端点需要使用websocket装饰器来定义，而不是get装饰器：

@app.websocket("/ws_res")
async def websoc(websocket: WebSocket):
    await websocket.accept()
    for i in range(100000):
        i = "John"
        await asyncio.sleep(0.01)
        await websocket.send_json({"msg": i})
    await websocket.close()

有关完整详细信息，请参阅文档：https ://fastapi.tiangolo.com/advanced/websockets/

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