The parameters dictionary contains a null entry for parameter 'id' when change in Routing

Question

I have done Routing in my routeConfig file as below.

public static void RegisterRoutes(RouteCollection routes)
        {
            routes.IgnoreRoute("{resource}.axd/{*pathInfo}");

            routes.MapRoute(
                name: "Search",
                url: "{controller}/{action}/{department}/{name}",
                defaults: new { controller = "Search", action = "Result",name =UrlParameter.Optional}
                );

            routes.MapRoute(
                name: "Default",
                url: "{controller}/{action}/{id}",
                defaults: new { controller = "Home", action = "Index", id = UrlParameter.Optional }
            );
        }

I want only name parameter should be optional, so made this this by writing

name =UrlParameter.Optional

But now when I click on this link

@Html.ActionLink("Edit", "EditEmployee", new { id = item.Id })

It gives me exception "The parameters dictionary contains a null entry for parameter 'id'"

Case 1: but when I do this,

defaults: new { controller = "Search", action = "Result"}

Removing name optional, It works fine.

case 2: When I do this

defaults: new { controller = "Search", action = "Result", department =UrlParameter.Optional, name=UrlParameter.Optional}

making both parameter optional, also works fine , but now Url generating for Edit is as follow

http://localhost:12190/Home/EditEmployee?id=1

but I want clean URL like this http://localhost:12190/Home/EditEmployee/1.

So How can get both,only name parameter optional and also a clean URL.

Answer 1

You've got two routes and it seems like you mixed them in your mind. The path you provided (http://localhost:12190/Home/EditEmployee?id=1) refers to the second route while department and name parameters - to the first one.

Maybe you need to comment the first route and try to get everything working with your set of parameters - action and id. Also you can try to use attribute routing to specify routes to your controllers and actions