Path_param not available in authentication middleware

[Kolumbs]

I expected a successful call here on curl http://127.0.0.1:8000/45

from starlette.applications import Starlette
from starlette.authentication import AuthCredentials, AuthenticationBackend, SimpleUser
from starlette.middleware import Middleware
from starlette.middleware.authentication import AuthenticationMiddleware
from starlette.responses import PlainTextResponse
from starlette.routing import Route


class AuthBackend(AuthenticationBackend):

    async def authenticate(self, request):
        assert "doc_id" in request.path_params # Dictionary is empty here
        return AuthCredentials(), SimpleUser("john")


def doc(request):
    assert "doc_id" in request.path_params # All good here
    return PlainTextResponse('OK')


routes = [
    Route("/{doc_id:int}", doc),
]

middleware = [
    Middleware(AuthenticationMiddleware, backend=AuthBackend()),
]

app = Starlette(debug=True, middleware=middleware, routes=routes)

[igolkotek]

To my regret, this is correct Starlette behavior as according to documentaion Using middleware the order of every request is as following:

• middleware
• routing
• end point

[alex-oleshkevich]

See my explanation here - #2208

TLDR: use middleware bound to Mount, not global.