Make ASP.NET MVC Route Id parameter required

Question

I have this route:

routes.MapRoute(
            "PlaceDetails",
            "{controller}/{action}/{id}",
            new { controller = "Place", action = "Details", id = UrlParameter.Optional }
        );

This routes this fine: mysite.com/place/details/123

Making Id 123 available to the details action of the place controller - which can then lookup place '123'.

However - this URL is also passed to the controller: mysite.com/place/details/

I want this to return HttpNotFound - but it sends a null Id to the controller - and requires me to handle that.

It seems neater if the route itself achieves this rather than needing unseemly null checks in the controller itself.

I have found nothing in Google about this specific issue.

How can I do this?

Answer 1

To make the id value required, you must not set it as UrlParameter.Optional or provide any other default value. With no value in the URL segment, and no default, the route won't match the request.

routes.MapRoute(
    "PlaceDetails",
    "{controller}/{action}/{id}",
    new { controller = "Place", action = "Details" }
);

But you probably also need to constrain the route in another way to prevent it from matching in cases where it shouldn't.

routes.MapRoute(
    "PlaceDetails",
    "Place/{action}/{id}",
    new { controller = "Place", action = "Details" }
);

See Why map special routes first before common routes in asp.net mvc? for details and additional options.