How do I know if the OutputCache for a given control is being used?

Question

I am attempting to write a common "menu.ascx" usercontrol in Asp.Net MVC that will generate a properly formatted HTML menu for my application. The menu is generated based on content in the database and a series of Resource resolutions... which are passed to the PartialView through an attribute on a ViewModel.

It would make sense to utilize an OutputCache directive on the menu.ascx control in order to limit the number of round-trips to the database and Resource files. My intention is to mark the OutputCache directive with VaryByParam=none and VaryByCustom attributes, implementing a custom security lookup in global.asax...

My question is: how do we know when the OutputCache for menu.ascx is going to be used, so that we can skip the data fetch operations when constructing the ViewModel in the controller?

---

Some sample UserControl code:

<%@ Control Language="C#" Inherits="System.Web.Mvc.ViewUserControl"  %>
<%@ OutputCache VaryByParam="none" VaryByCustom="customstring" %>
<ul>
<% var model = (IMyViewModel)Model; 
 foreach (var menu in model.Menus) { %>
   <li><a href="<%= menu.href %>"><%= menu.Text %></a></li>
<% } %>
</ul>

Answer 1

Here's interesting readin on that subject Donut Hole Caching in ASP.NET MVC and here ASP.NET MVC Result Cache , I would basically do this menu by RenderAction method in master page to invoke action which will pull data from database and theb , and then cache the action result

Answer 2

I think I have found a suitable workaround to my problem.

In the Menus property getter for my concrete ViewModel implementation, I am writing proxy code to reach back into the instantiating Controller and request the Menu data. In this way, I can create the Menu data on-the-fly, when the PartialView requests it. If the PartialView is coming out of the OutputCache, the Menu property will not be requested.

So, my IMyViewModel looks a little like this:

public interface IMyViewModel {

  IEnumerable<Menu> Menus { get; }

  ///<summary>
  /// A pointer back to the calling controller, which inherits from the abstract MyBaseController
  ///</summary>
  MyBaseController Controller { get; set; }

}

and my concrete implementation of Menus looks a little like this:

public IEnumerable<Menu> Menus 
{
   get { return Controller.GetMenus(); }
}

Comments? Is this a viable solution?