ASP.NET Routing - Route Constraint with database lookup

Question

I'm just starting out with C# and ASP.NET and have the following questions. I am working with code adapted from a couple different tutorials playing with Northwind and have gotten this far. The list of acceptable categories is currently hard coded in a string but I would like to look up the CategoryName in the database to verify that it exists.

Obviously the purpose of this is to ensure that users don't just type:
www.domain.com/Categories/AnyUrlWillWork and return a valid page.

Also does anyone have an tips of how they are dealing with capitalization issues since the routing is case sensitive? For example Categories/beverages should forward to Categories/Beverages ?

Thanks in advance for any assistance, and glad to be joining Stack Overflow.

//Complex contraint class
public class EchoConstraint : IRouteConstraint
{
    public readonly string[] ValidMessages = { "Beverages", "Produce", "Confections", "Seafood" };

    public bool Match(HttpContextBase httpContext, Route route, string parameterName, RouteValueDictionary values, RouteDirection routeDirection)
    {
        string message = values["CategoryName"] as string;
        return ValidMessages.Contains(message);
    }
}


//Routes
RouteTable.Routes.MapPageRoute(
                        "Category Route",                       // Route name
                        "Categories/{CategoryName}",            // Url pattern
                        "~/ShowProductsInCategory.aspx",        // Physical file
                        true,
                        new RouteValueDictionary            
                            {{"CategoryName", "Beverages"}},         //Sets default value if none is provided in URL
                        new RouteValueDictionary 
                            {{"CategoryName", new EchoConstraint()}}
                           );

Answer 1

Is this MVC? If so, why not route to a function, which will check the category name against your data store and redirect to an error page if such category doesn't exist?

public ActionResult Index(string catName)
{
    if (string.IsNullOrEmpty(catName) || !MyCategoriesDataStore.Exists(catName))
        return RedirectToAction("CategoryError");

    // Load category data to be used from View

    return View();
}

A WebForms solution would be:

    public class EchoConstraint : IRouteConstraint
    {
        private IRepository rep;
        public EchoConstraint(IRepository r) { rep = r; }

        public bool Match(HttpContextBase httpContext, Route route, string parameterName, RouteValueDictionary values, RouteDirection routeDirection)
        {
            return rep.GetCategory(message) == 0;
        }
    }
.
.
.
                        new RouteValueDictionary 
                            {{"CategoryName", new EchoConstraint(myDataAccessRepo)}}
                           );

Where you pass an object of class implementing IRepository with your data access logic (using NHibernate, EntityFramework or your own DAL implementation). You need to return a bool value, and this is what I did.