ASP.NET MVC - Find Absolute Path to the App_Data folder from Controller

What is the correct way to find the absolute path to the App_Data folder from a Controller in an ASP.NET MVC project? I'd like to be able to temporarily work with an .xml file and I don't want to hardcode the path.

This does not work:

[HandleError]
public class HomeController : Controller
{
    public ActionResult Index()
    {
        string path = VirtualPathUtility.ToAbsolute("~/App_Data/somedata.xml");

        //.... do whatever 

        return View();
    }

}

I think outside of the web context VirtualPathUtility.ToAbsolute() doesn't work. string path comes back as "C:\App_Data\somedata.xml"

Where should I determine the path of the .xml file in an MVC app? global.asax and stick it an application-level variable?

ASP.NET MVC1 -> MVC3

string path = HttpContext.Current.Server.MapPath("~/App_Data/somedata.xml");

ASP.NET MVC4

string path = Server.MapPath("~/App_Data/somedata.xml");

HttpServerUtility.MapPath Method

string path = AppDomain.CurrentDomain.GetData("DataDirectory").ToString();

This is probably a more "correct" way of getting it.

I try to get in the habit of using HostingEnvironment instead of Server as it works within the context of WCF services too.

 HostingEnvironment.MapPath(@"~/App_Data/PriceModels.xml");