MVC 5 Render View to String

ViewExtensions.cs

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

namespace Website.Infrastructure {
    public static class ViewExtensions {
        //Renders the view to a string
        public static string RenderToString(this PartialViewResult partialView) {
            HttpContext httpContext = HttpContext.Current;

            if (httpContext == null) {
                throw new NotSupportedException("An HTTP context is required to render the partial view to a string");
            }

            string controllerName = httpContext.Request.RequestContext.RouteData.Values["controller"].ToString();

            ControllerBase controller = (ControllerBase)ControllerBuilder.Current.GetControllerFactory()
                .CreateController(httpContext.Request.RequestContext, controllerName);

            ControllerContext controllerContext = new ControllerContext(httpContext.Request.RequestContext, controller);

            string viewName = partialView.ViewName;
            if (string.IsNullOrWhiteSpace(viewName)) {
                // Use the action name if a view name is not supplied
                viewName = httpContext.Request.RequestContext.RouteData.Values["action"].ToString();
            }
            var view = ViewEngines.Engines.FindPartialView(controllerContext, viewName).View;

            using (StringWriter sw = new StringWriter())
            using (HtmlTextWriter tw = new HtmlTextWriter(sw)) {
                view.Render(new ViewContext(controllerContext, view, partialView.ViewData, partialView.TempData, tw), tw);

                return sw.GetStringBuilder().ToString();
            }
        }
    }
}