Overwrite/extend FastAPI - APIRouter route

[efirvida]

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Example Code

import uvicorn
from fastapi import APIRouter, FastAPI

router = APIRouter()


@router.get("/")
def index():
    return "hello world!"


@router.get("/")
def new_index():
    return "hello world 2!"


app = FastAPI()
app.include_router(router)

if __name__ == "__main__":
    uvicorn.run("server:app")

Description

I copy here my thread in StackOverflow

So... I'm trying to create a simple pluggable FastAPI application where plugins can add, or not, API endpoints. Now is working fine so every plugin adds its own API endpoints. But what if a plugin can extend other plugins, to add or modify its endpoints...

For that, I build a plugin graph to handle the plugin dependencies and now a plugin can import the router from its dependencies and add some new endpoints. But I can´t overwrite the existing endpoints with the new routes.

I have also found an interesting thing in the generated API /docs that maybe can be a bug. The sample code generates this doc, which seems to be OK to me:

But... the endpoint returns the wrong response:
At this point, I spect to have a "hello world 2!" response from new_index not a "hello world!" from index

Following a suggestion in the StackOverflow comment, I found this solution which I'm not happy with

class Router(APIRouter):
    def add_api_route(...) -> None:
        ...

        route_index = self._get_route_index_by_path(route.path)
        if route_index >= 0:
            self.routes[route_index] = route
        else:
            self.routes.append(route)

    def _get_route_index_by_path(self, path: str) -> int:
        for index, route in enumerate(self.routes):
            if route.path == path:
                return index
        return -1


app = FastAPI()
router = Router()
....

I mean I'm not happy because I can´t find a good way to replace the route, since the __eq__ to check if the route is in the list is on starlette.routing.Route so this was a simplest solution that I Found

Operating System

Linux

Operating System Details

Fedora 35

FastAPI Version

0.77.1

Python Version

Python 3.10.4

Additional Context

No response

[raphaelauv]

there is a wip about routes -> #4794

[efirvida]

@raphaelauv but I don´t direct a solution for my case in that PR. In the documentation of the PR I read something about supporting the same endpoint with different dependencies, that is OK, and I think is very important but in my case, I want to overwrite the endpoint.

[rbrown021]

I am doing something similar where I am making some plugins with their own routes and models. But I want whoever uses them to be able to extend the models and routes and update the routes. This would be super helpful!