Could this line in litestar be simplified? Are the type hints correct?

[bunny-therapist]

I have this exact line from PrometheusMiddleware in my own middleware,

request = Request[Any, Any, Any](scope, receive)
method: str = request.method if request.scope["type"] == ScopeType.HTTP else request.scope["type"]

and when I enabled the mypy error code "redundant-expr", that line was flagged, because request.scope["type"] is always ScopeType.HTTP, see https://github.com/litestar-org/litestar/blob/main/litestar/connection/request.py#L65 and https://github.com/litestar-org/litestar/blob/main/litestar/types/asgi_types.py#L149

So if the type hints are correct, I should just be able to change this to

request = Request[Any, Any, Any](scope, receive)
method: str = request.method

and it would be equivalent.

So the question is, is this correct? So that line in the litestar PrometheusMiddleware could also be simplified? I would just change it, but given that litestar has that line in their code, I am worried I will break something somewhere.

[provinzkraut]

I believe the more correct way to express this would be

if connection.scope["type"] == ScopeType.HTTP:
 request = Request[Any, Any, Any](scope)
 method = request.method
else:
 method = scope["type"]

since it doesn't make sense to create a request for a non-http connection.

[bunny-therapist]

My middleware is a subclass of PrometheusMiddleware and its PrometheusConfig has scopes={ScopeType.HTTP} - is that why it is currently working then, and why the Request instantiation is not breaking anything? Because the middleware always just gets http-connections?

[provinzkraut]

Yeah. It's unfortunately very hard to type correctly. It's not impossible, it could be done via generics, but that's super unwieldy.

If you want, you could just throw a scope = typing.cast(scope, HttpScope) in there, to make it more explicit. Otherwise your suggestion should also be safe.