如何从中间件设置属性以请求 FastAPI 中的对象？

Question

如何从中间件函数中为Request 对象设置任意属性？

from fastapi import FastAPI, Request

app = FastAPI()


@app.middleware("http")
async def set_custom_attr(request: Request, call_next):
    request.custom_attr = "This is my custom attribute"
    response = await call_next(request)
    return response


@app.get("/")
async def root(request: Request):
    return {"custom_attr": request.custom_attr}

此设置引发异常，

AttributeError: 'Request' 对象没有属性 'custom_attr'

那么，如何在我的路由器中获取 "This is my custom attribute" 值？

Answer 1

我们无法将属性附加/设置到 request 对象（如果我错了，请纠正我）。

但是，我们可以使用Request.state--(Doc) 属性

from fastapi import FastAPI, Request

app = FastAPI()


@app.middleware("http")
async def set_custom_attr(request: Request, call_next):

    request.state.custom_attr = "This is my custom attribute" # setting the value to `request.state`

    response = await call_next(request)
    return response


@app.get("/")
async def root(request: Request):
    return {"custom_attr": request.state.custom_attr} # accessing the value from `request.state`