mvc parameter dictionary contains null entry ..... routing error/problem

So I have this controller called Cars, and it has:

namespace MySite.Controllers
{
    public class CarsController : ApplicationController
    {

        public ActionResult Index()
        {
            return View();
        }

        public ActionResult New()
        {
      开发者_JAVA百科      return View();
        }
        [httppost]
        public ActionResult New()
        {
            return View();
        }


        public ActionResult Details(int id)
        {
            return View();
        }
    }
}

Global asax

       routes.MapRouteLowerCase(
            "Cars", // Route name
            "Cars/{id}", // URL with parameters
            new { controller = "Cars", action = "Details", id = URLParameter.Optional}
        );

       routes.MapRouteLowerCase(
            "Default", // Route name
            "{controller}/{action}/{id}", // URL with parameters
            new { controller = "Home", action = "Index", id = URLParameter.Optional} // Parameter defaults
        );

So following is the error I'm getting:

the parameters dictionary contains a null entry for parameter of non nullable type for method in

NOTE: It's getting me redirected to the "Details" View and is asking for an int even thought I wanted to go to the "New" view. I'm not really sure what's happening? I basically wanted to have my urls lowercased while removing the "action" on the url on the Promoter routing...Does that make sense? Anyhelp is appreciated! Thanks!!!

---

All code below applies to the first route definition.
Second route definition should stay as it is.

Your routing is invalid

Take a look at the first route definition:

routes.MapRouteLowerCase(
    "Cars", // Route name
    "Cars/{id}", // URL with parameters
    new { controller = "Cars", action = "Details", id = URLParameter.Optional}
);

And when you access Cars/New this first route gets hit because all parameters are easily applied as:

• controller = "Cars"
• action = "Details"
• id = "New"

If you'd like the first route definition to only cover certain IDs you should put a constraint onto it or change your routing. Constraint for numeric IDs should look like this:

routes.MapRouteLowerCase(
    "Cars", // Route name
    "Cars/{id}", // URL with parameters
    new { controller = "Cars", action = "Details" },
    new { id = @"\d+" }
);

When you'd access Cars/New first route wouldn't be hit because New doesn't satisfy ID constraint so route processing would continue with the next route (which would resolve it just fine - as it should).

Mind the fact, that id isn't optional anymore. In case of putting a constraint onto it it can't be. If you have a Details controller action it should most probably display some certain details. So it actually needs some ID.

---

If your route is setted like this

routes.MapRouteLowerCase(
    "Cars", // Route name
    "Cars/{id}", // URL with parameters
    new { controller = "Cars", action = "Details", id = URLParameter.Optional}
);

that means that any URL that starts with "/Cars/..." will redirect you to Details action, that includes "/Cars/New" and it will try to map the "New" string to the id parameter that is why you get the error.