This version is based on the work of Tim McCall, found at https://github.com/mccalltd/AttributeRouting

It brings a richer syntax that you can use in your route URL to specify constraints inline.

Inline constraints

You can use the following syntax to constraint the parameter to be of the required type:

// Restrict the 'id' parameter to digits only
// Restrict the 'name' parameter to any string with a maximum length of 50-
[GET("my-url/{id:int}/{name:string(50)}")]

Here is the full list of built-in type restrictions:

string(max-length), bool, int, long, float, double, decimal

You can also add a regular expression constraint by using the following syntax:

// Restrict 'someParam' to letters only
[GET("my-url/{someParam:regex(^[a-zA-Z]+$)}")

Extensibility

You can easily add your own type of constraints. For example, here's how to create a constraint for even numbers:

1. Create a new class that implements IRouteConstraint:

   public class EvenRouteConstraint : IRouteConstraint
   {
       public bool Match(HttpContextBase httpContext, Route route, string parameterName, RouteValueDictionary values, RouteDirection routeDirection)
       {
           var value = values[parameterName];
           if (value == null)
               return true;
   
           int intValue;
           if (!int.TryParse(value.ToString(), out intValue))
               return false;
   
           return intValue % 2 == 0;
       }
   }
   

2. Register this constraint, somewhere in your Application_Start:

   using AttributeRouting.Constraints;
   ...
   
   protected void Application_Start()
   {
       RouteConstraintFactory.RegisterConstraintType("even", typeof(EvenRouteConstraint));
   }
   

3. Use the constraint:

   // Restricts 'someParam' to be an even number
   [GET("my-url/{someParam:even}")]
   

Support for Enums

You can restrict a parameter to the values of an enum:

1. Create an enum:

   public enum Colors
   {
       Red,
       Green,
       Blue
   }
   

2. Register the new constraint type:

   RouteConstraintFactory.RegisterConstraintType("color", typeof(EnumRouteConstraint<Colors>));
   

3. Apply the constraint to a URL parameter:

   // Restrict 'someParam' to values 'red', 'green' and 'blue'
   [GET("my-url/{someParam:color}")]