MVC5 attribute-based routing for subdomains?

Question

MVC5 attribute-based routing for subdomains?

How can I route subdomain-based URLs in ASP.NET MVC5 using attribute-based routing ? I know this post , but we are trying to switch to a cleaner attribute-based approach, and I would like to move my route

from http://domain.com/Account/Logout/

to http://my.domain.com/Account/Logout/

Without routing subdomains, this standard code works:

[RoutePrefix("Account")]
public class AccountController : ApiController
{
    [Route("Logout")]
    public IHttpActionResult Logout()
    {
       // logic
    }
}

To add subdomain-based routing, I wrote my own attribute and user restriction. The attributes are mostly replaced Route, so I can specify a subdomain, but my custom attribute is SubdomainRoutenot working. My attempt below. I assume that a more efficient implementation will also set up an attribute RoutePrefixto define subdomains ...

SubdomainRoute

public class SubdomainRouteAttribute : RouteFactoryAttribute
{
    public SubdomainRouteAttribute(string template, string subdomain) : base(template)
    {
        Subdomain = subdomain;
    }
    public string Subdomain
    {
        get;
        private set;
    }
    public override RouteValueDictionary Constraints
    {
        get
        {
            var constraints = new RouteValueDictionary();
            constraints.Add("subdomain", new SubdomainRouteConstraint(Subdomain));
            return constraints;
        }
    }
}

SubdomainRouteConstraint

public class SubdomainRouteConstraint : IRouteConstraint
{
    private readonly string _subdomain;

    public SubdomainRouteConstraint(string subdomain)
    {
        _subdomain = subdomain;
    }

    public bool Match(HttpContextBase httpContext, Route route, string parameterName, RouteValueDictionary values, RouteDirection routeDirection)
    {
        return httpContext.Request.Url != null && httpContext.Request.Url.Host.StartsWith(_subdomain);
    }
}