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middleware

Middlewares​

Both Lihil and Route has add_middleware API that accept one, or a sequence of MiddlewareFactory.

a MiddlewareFactory is a callable that receives one positional argument of type ASGIApp and returns a ASGIApp. for example:

# This piece of code is for demonstration only.

def tracingmw_factory(next_app: ASGIApp) -> ASGIApp:
    async def tracemw(scope, receive, send):
        scope["trace_id"] = str(uuid.uuid4())
        await next_app(scope, receive, send)
    return trace_mw

lhl = Lihil(middlewares=[lambda app: tracingmw_factory(app)])

lihil uses starlette internally, you can directly import middlewares from starlette, for example:

from starlette.middleware.cors import CORSSMiddleware

lhl = Lihil(middlewares=[lambda app: CORSMiddleware(app, add_methods="*")])

for complex middleware that require many external dependencies, you might to construct them inside lifespan, so that you can use lhl.graph to resolve dependencies.