如何修复尝试使用websockets从FastAPI获取实时数据流时的错误(不支持的升级请求)

Question

如何获得每次迭代的响应，就像实时流提要一样？

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，我正试图从python代码中获得响应，但我收到一个错误，上面写着Unsupported upgrade request.

以下是API方面的输出：

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.

下面是我用来访问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

Answer 1

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

@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()

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