add_exception_handler type annotation does not accept coroutines

[fpiche]

A related discussion was answered here but does not fully describe my issue #2391

Since the introduction of the ExceptionHandler type, a coroutine cannot be passed to add_exception_handler.

Example:

I have an async function with signature

async def exc_handler(self, request: Request, exc: HTTPException) -> JSONResponse: 

and am passing it to add_exception_handler like so:

app.add_exception_handler(HTTPException, exc_handler)

But mypy is complaining that I’m passing the wrong type:

Argument 2 to "add_exception_handler" of "Starlette" has incompatible type "Callable[[Request, HTTPException], Coroutine[Any, Any, JSONResponse]]"; expected "Callable[[Request, Exception], Response | Awaitable[Response]] | Callable[[WebSocket, Exception], Awaitable[None]]"

A workaround i found for now is to add exception handlers during app creation since I'm using FastAPI: FastAPI(exception_handlers={HTTPException: exc_handler}) since this accepts the coroutine type.

[Jodagito]

I'm going thought this exact same problem. Thing is when adding multiple exception handlers to the FastAPI object then it won't be clean at all, one could use the exception_handlers list from the FastAPI object and replace the add_exception_handler method, this new method would just populate the list of dicts.