route_class not respected in nested router when trying to use custom APIRoute class

[jgould22]

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Example Code

The below code is a small working example

import time
from typing import Callable

from fastapi import APIRouter, FastAPI, Request, Response
from fastapi.routing import APIRoute


class TimedRoute(APIRoute):
    def get_route_handler(self) -> Callable:
        original_route_handler = super().get_route_handler()

        async def custom_route_handler(request: Request) -> Response:
            before = time.time()
            response: Response = await original_route_handler(request)
            duration = time.time() - before
            response.headers["X-Response-Time"] = str(duration)
            print(f"route duration: {duration}")
            print(f"route response: {response}")
            print(f"route response headers: {response.headers}")
            return response

        return custom_route_handler


app = FastAPI()
router = APIRouter(route_class=TimedRoute)

@app.get("/")
async def not_timed():
    return {"message": "Not timed"}


@router.get("/timed")
async def timed():
    return {"message": "It's the time of my life"}


app.include_router(router)

The above works and the router is timed correctly

The below does not and the route is not timed

import time
from typing import Callable

from fastapi import APIRouter, FastAPI, Request, Response
from fastapi.routing import APIRoute


class TimedRoute(APIRoute):
    def get_route_handler(self) -> Callable:
        original_route_handler = super().get_route_handler()

        async def custom_route_handler(request: Request) -> Response:
            before = time.time()
            response: Response = await original_route_handler(request)
            duration = time.time() - before
            response.headers["X-Response-Time"] = str(duration)
            print(f"route duration: {duration}")
            print(f"route response: {response}")
            print(f"route response headers: {response.headers}")
            return response

        return custom_route_handler


router_1 = APIRouter()

@router_1.get("/")
async def not_timed():
    return {"message": "Not timed"}


@router_1.get("/timed")
async def timed():
    return {"message": "It's the time of my life"}

# The route is no longer timed
router = APIRouter(route_class=TimedRoute)
router.include_router(router_1)

# This also doesnt work 
# router = APIRouter()
# router.include_router(router_1)
# router.route_class = TimedRoute

app = FastAPI()
app.include_router(router)

Description

Trying use a a router with a custom APIRoute class I have included a small example based on the documentation at https://fastapi.tiangolo.com/advanced/custom-request-and-route/?h=

• Run sample code with uvicorn
• Make a request to /timed
• Get {"message": "It's the time of my life"} when requesting but not get the extra header, nor are the lines logged

This may or may not be related to the below issues, they were not very clear

• include_router reset all attribute #3435
• bug:include_router reset all attribute #3658

Operating System

Linux

Operating System Details

[jordan@box]$ lsb_release -a
LSB Version:    1.4
Distributor ID: EndeavourOS
Description:    EndeavourOS Linux
Release:        rolling
Codename:       rolling

[jordan@box]$ uname -a
Linux box 5.14.14-arch1-1 #1 SMP PREEMPT Wed, 20 Oct 2021 21:35:18 +0000 x86_64 GNU/Linux

FastAPI Version

fastapi==0.70.0

Python Version

Python 3.9.7

Additional Context

No response

[gamgi]

@jgould22 I tried to reproduce the issue in a notebook here with slight changes: tinnable.com/tins/13c1743f-07c6-4260-9fd8-1f9a7f2b91d7. With the changes, it does not reproduce.

It seems that the issue is fixed by changing

- router_1 = APIRouter()
+ router_1 = APIRouter(route_class=TimedRoute)

It is not enough that the parent router has the route_class. The subrouter router_1 with the endpoint definition also has to be of the custom class. This is not mentioned in the docs, but seems at least initially reasonable, since it is not clear how nested route classes should be propagated.

[jgould22]

Yeah. I know you can define a custom_route_handler for all the routers and it works.

I was hoping I could do it for only a subset of my routes.

The docs imply in some places you can treat the APIRouter as a mini FastAPI class but I guess this has some exceptions.

I will try instead to use a sub-application to split things instead of a router.

Thanks for your help.