asp.net map route with parameter inside controller and view - asp.net-mvc-2

Question

I need to create a url scheme like this
friend/{userid}/wishlist
where friend is the controller, wishlist is the view, and userid is the id of hte friend whose wishlist you would like to see.
I have setup a route like this
routes.MapRoute(
"FriendWishlist",
"friend/{userid}/wishlist",
new { controller = "WishList", action="FriendWishlist", userid = 123}
);
when i try to browse to /friend/123/wishlist i get the following error
A public action method '123' was not
found on controller
'GiffrWeb.Areas.Api.Controllers.FriendController'.

Answer 1

Routes in MVC are evaluated in the order they are declared. It sounds very much like you have declared your route below the default one:
routes.MapRoute(
"Default",
"{controller}/{action}/{id}",
new { controller = "Home", action = "Index", id = UrlParameter.Optional }
);
routes.MapRoute(
"FriendWishlist",
"friend/{userid}/wishlist",
new { controller = "WishList", action="FriendWishlist", userid = 123}
);
So the MVC framework is trying to match your URL /friend/123/wishlist first to the default route. Because it's all variables and everything has a default or is optional, it's guaranteed to match. It doesn't check if the controllers and actions exist and take the relevant arguments. You have a FriendController class - check. 123 action - it goes bang.
Simplest fix - declare the route above the default one (ie just swap these two statements) and it should work OK.
I might just add that it seems a little weird to have a URL that starts with /friend/ going to a WishList controller when you obviously have a Friend controller (your error message says so).
Finally, I can't recommend highly enough that if you introduce custom routing that you also test those routes thoroughly - as you have seen, the routing engine often might not do what you think it does. I recommend either the route testing stuff in MvcContrib or Brad Wilson's blog post.