Attribute Based Routing In ASP.NET MVC 5

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

public static void RegisterRoutes(RouteCollection routes)  
{  
    routes.IgnoreRoute("{resource}.axd/{*pathInfo}");  
tes.MapMvcAttributeRoutes(); //Enables Attribute Based Routing  
    routes.MapRoute(  
        name: "Default",  
        url: "{controller}/{action}/{id}",  
        defaults: new { controller = "Product", action = "List", id = UrlParameter.Optional }  
    );      
} 

[Route("products/{id?}")]  
      public ActionResult Details(string id)   
      {  
          if (string.IsNullOrEmpty(id))   
          {  
              return View("List", GetProductList());  
          }          
          return View("Details", GetProductDetails());  
      }

As shown in the method above, the Route is defined on a Details action method that lets users access the product details page either by of these paths,

/Product/Details/Id or /products/id

You might have observed the question mark in the route above, all it indicates is that the id is an optional parameter of the route, and hence the action method logic checks if the id is null. It will show you the product listing page.

Route Prefixes

Route Prefixes are nothing but the prefix for any route that we want to apply, all we need to do is define the route prefix on a controller so that all the action methods inside it can follow the prefix.

For example

[RoutePrefix("products")]  
    public class ProductController : Controller  
    {  
        //This will be translated to /products  
        [Route]  
        public ActionResult List()  
        {  
            return View();  
        }  
        //This will be translated to /products/2  
        [Route("{id?}")]  
        public ActionResult Details(string id)   
        {  
            if (string.IsNullOrEmpty(id))   
            {  
                return View("List");  
            }  
            return View("Details");  
        }  
}  

Route Constraints

Route constraints are nothing but a set of rules that you can define on your routing model/parameters that users need to follow when accessing the defined routes.

The way to define a constraint is by using the ":" character, let's have a look at the example below.

For example

//route gets called as /products/productname  
    [Route("products/{id:alpha}")]  
        public ActionResult GetProduct(string name)  
        {  
            return View();  
        }  
//route gets called as /products/2  
        [Route("products/{id:int}")]  
        public ActionResult GetProduct(int id)  
        {  
            return View();  
        }

Now you might have observed in the example above that though the method name is the same the route's parameter has some constraint on it. In other words, the first method will be called if the route is accessed with a string as a parameter and the second method will be called if the route is accessed with an integer in the route parameter.

You can also define your custom route constraints using an IRouteConstraint interface.

Route Areas

A Route area is nothing but a way to specify the area in a route, basically just to let the route know that the controller belongs to some area.

[RouteArea("business")]  
    [RoutePrefix("products")]  
    public class ProductController : Controller  
    {  
        //This will be translated to /business/products/list  
        [Route]  
        public ActionResult List()  
        {  
            return View();  
        }  
}