Some i18n issue because of the order of request processing

[igolkotek]

Hi

I'd like to reailize i18n language prefix to url (like in Django) solution.
That is every url will have a language prefix like "/en/auth/user", "/fr/auth/user".

It could be done perfect with double Mount, which is not mentioned in the documentation, but tested.
That is the top level Mount("/{language:user_language}") determines language,
and the lower Mounts includes routes from every library added to the project.
And it works! But the idea is to add a middleware which could take a param_path["language'] and activate translation language somehow.
But a middleware doesn't see param_paths as, according to @tomchristie "..the routing only occurs after the middleware handling."

Could anybody help me with the idea, how to do it nice way, please?

Igor

[alex-oleshkevich]

Seems it works out of the box:

from starlette.applications import Starlette
from starlette.responses import Response
from starlette.routing import Mount, Route
from starlette.middleware import Middleware


def index(request):
    return Response(request.state.lang) # get value set in the middleware


class LangMiddleware:
    def __init__(self, app):
        self.app = app

    async def __call__(self, scope, receive, send):
        language_from_path = scope['path_params']['lang']
        scope.setdefault('state', {})
        scope['state']['lang'] = language_from_path # make it available as request.state.lang

        # activate_translation(language_from_path) # activate translations
        await self.app(scope, receive, send)


app = Starlette(
    debug=True,
    routes=[
        Mount(
            '/{lang}',
            routes=[Route('/login', index)],
            middleware=[Middleware(LangMiddleware)],
        )
    ],
)

[alex-oleshkevich]

Tom mentions that only the final route matching happens after the middleware (eg. finds the corresponding endpoint callback for the given URL).

[alex-oleshkevich]

However, if you use a global middleware then no route matcher (Route nor Mount) is called thus no path_params.

[igolkotek]

Great! Thank you
It works )