How to generate url in global.asax using my route. int asp.net mvc

I have functionality in BeginRequest event in global.asax which parse request url, check some parts of this and redirect user to another url.

Problem: how to generate url from routeName. I want to do this, because if route will be changed, redirect functionality will be working. I don't like code:

String.Format("{0}/{1}/{2}", host, part1, part2);

In view I can use Url.RouteUrl, but in global.asax i have to create UrlHelper object manually with RequestContext a开发者_如何学Pythonnd RouteData parameters. Where can i get the routedata object?

I have functionality in BeginRequest event in global.asax which parse request url, check some parts of this and redirect user to another url.

A more MVCish way to achieve this would be to use a custom action filter and perform this processing in the OnActionExecuting method which will be called before the controller action is invoked:

public class CustomFilterAttribute : ActionFilterAttribute
{
    public override void OnActionExecuting(ActionExecutingContext filterContext)
    {
        // read some value from the request
        string value = filterContext.RequestContext.RouteData.Values["someValue"] as string;
        if (!IsValueValid(value))
        {
            // if the value is invalid redirect to some controller action
            filterContext.Result = new RedirectToRouteResult(
                new RouteValueDictionary(new
                {
                    action = "foo",
                    controller = "bar"
                })
            );
        }
        else
        {
            base.OnActionExecuting(filterContext);
        }
    }
}

And now all that's left is to decorate your base controller with this attribute so that it applies to all actions.