ASP.NET MVC render Razor Partial View as String Error? - string

Question

I am using this code to try and render a razor partial view as a string for the purposes of sending an email.
public static string RenderPartialToString(
string userControlPath,
object viewModel,
ControllerContext controllerContext,
TempDataDictionary tempData)
{
using (var writer = new StringWriter())
{
var viewDataDictionary = new ViewDataDictionary(viewModel);
var view = new WebFormView(controllerContext, userControlPath);
var viewContext = new ViewContext(
controllerContext,
view,
viewDataDictionary,
tempData,
writer
);
viewContext.View.Render(viewContext, writer);
return writer.GetStringBuilder().ToString();
}
}
The problem is that I get the follow error:
must derive from ViewPage, ViewPage<TModel>, ViewUserControl, or ViewUserControl<TModel>. Stack Trace: at System.Web.Mvc.WebFormView.RenderView(ViewContext viewContext, TextWriter writer, Object instance) at .... RenderPartialToString
How would I fix that ?

Answer 1

Indeed, WebFormView doesn't inherit from the mentioned classes, just IView. I did a little Google research and got a prototype working. This page was the most helpful.
I created an empty MVC3 application and created the following HomeController. When I run the application, the page shows the rendered string. The resultAsString variable shows how to capture the rendering as a string.
using System;
using System.IO;
using System.Web.Mvc;
public class HomeController : Controller
{
public ActionResult Index()
{
var result = RenderPartial(this.ControllerContext, "This is #DateTime.Now right now");
var resultAsString = result.Content;
return result;
}
private ContentResult RenderPartial(ControllerContext controllerContext, string template)
{
var temporaryViewPath = string.Format("~/Views/{0}.cshtml", Guid.NewGuid());
using (var stringWriter = new StringWriter())
{
using (var fileStream = System.IO.File.Create(Server.MapPath(temporaryViewPath)))
{
using (var streamWriter = new StreamWriter(fileStream))
{
streamWriter.WriteLine(template);
streamWriter.Close();
}
fileStream.Close();
}
var razor = new RazorView(controllerContext, temporaryViewPath, null, false, null);
razor.Render(new ViewContext(controllerContext, razor, new ViewDataDictionary(), new TempDataDictionary(), stringWriter), stringWriter);
System.IO.File.Delete(Server.MapPath(temporaryViewPath));
return Content(stringWriter.ToString());
}
}
}