Render View as String ASP.NET MVC 3/4

using System.IO;
using System.Web.Mvc;

public class RenderRazorViewToString
{
#region Render

public string Render( Controller controller, string viewName, object model )
{
controller
.ViewData.Model = model;

using ( var sw = new StringWriter() )
{
var viewResult = ViewEngines.Engines.FindPartialView(controller.ControllerContext, viewName);
var viewContext = new ViewContext(controller.ControllerContext, viewResult.View, controller.ViewData, controller.TempData, sw);
viewResult
.View.Render(viewContext, sw);
viewResult
.ViewEngine.ReleaseView(controller.ControllerContext, viewResult.View);
return sw.GetStringBuilder().ToString();
}
}

#endregion
}