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

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 ?

neontapir · Accepted Answer · 2012-06-21 22:05:41Z

2

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());
        }
    }
}

edited Jun 21, 2012 at 22:05

answered Jun 21, 2012 at 21:16

neontapir

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2 Comments

Andy Over a year ago

would you be able to specify some code ? what exactly should I define it as ?

neontapir Over a year ago

I posted code from a working prototype. The method signature is different, but you should be able to adapt it to your needs.

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