How to visually indicate current page in ASP.NET MVC?

Question

As a base for discussion. Create a standard ASP.NET MVC Web project.

It will contain two menu items in the master page:

Answer 1

The easiest way is to get the current controller and action from the ViewContext's RouteData. Note the change in signature and use of @ to escape the keyword.

<% var controller = ViewContext.RouteData.Values["controller"] as string ?? "Home";
   var action = ViewContext.RouteData.Values["action"] as string ?? "Index";
   var page = (controller + ":" + action).ToLower();
 %>

<%= Html.ActionLink( "About", "About", "Home", null,
                     new { @class = page == "home:about" ? "current" : "" ) %>
<%= Html.ActionLink( "Home", "Index", "Home", null,
                     new { @class = page == "home:index" ? "current" : "" ) %>

Note that you could combine this an HtmlHelper extension like @Jon's and make it cleaner.

<%= Html.MenuLink( "About", "About", "Home", null, null, "current" ) %>

Where MenuActionLink is

public static class MenuHelperExtensions
{
     public static string MenuLink( this HtmlHelper helper,
                                    string text,
                                    string action,
                                    string controller,
                                    object routeValues,
                                    object htmlAttributes,
                                    string currentClass )
     {
         RouteValueDictionary attributes = new RouteValueDictionary( htmlAttributes );
         string currentController = helper.ViewContext.RouteData.Values["controller"] as string ?? "home";
         string currentAction = helper.ViewContext.RouteData.Values["action"] as string ?? "index";
         string page = string.Format( "{0}:{1}", currentController, currentAction ).ToLower();
         string thisPage = string.Format( "{0}:{1}", controller, action ).ToLower();
         attributes["class"] = (page == thisPage) ? currentClass : "";
        return helper.ActionLink( text, action, controller, new RouteValueDictionary( routeValues ), attributes );
     }
}