Backload Example#4 doesn't work in VS2010 MVC4

Question

Backload Example #4 code not working.

public class FileUploadDerivedController : BackloadController
{
    // Since version 1.9 you can call the asynchronous handler method 
    public async Task<ActionResult> FileHandler()
    {            
        // Call base class method to handle the file upload asynchronously
        ActionResult result = await base.HandleRequestAsync();
        return result;
    }
}

I get this error:

'Backload.Controllers.BackloadController' does not contain a definition for 'HandleRequestAsync'

To reproduce:

• Using VS2010, open new MVC4 project.
• To enable async in VS2010, Install VS Async CTP: http://www.microsoft.com/en-us/download/details.aspx?id=9983
• In your project, reference: [VS Async CTP Install]\Microsoft Visual Studio Async CTP\Samples\AsyncCtpLibrary.dll

Using Package Manager Command

Install-Package Backload

• Download Examples from: https://github.com/blackcity/Backload
• Open Example #4 and copy the code from FileUploadController.cs for FileUploadDerivedController class.

usings

using Backload.Controllers;
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Web;
using System.Web.Mvc;
using Backload;
using System.Threading.Tasks;

Controller

// Change namespace to yours
namespace Backload.Examples.Example04.Controllers
{
    // For all demos below open the file  ~/Scripts/main.js and
    // change the url of the ajax call for the fileupload plugin

    // Demo 1: Derive from BackloadController and call the base class
    public class FileUploadDerivedController : BackloadController
    {
        // Since version 1.9 you can call the asynchronous handler method 
        public async Task<ActionResult> FileHandler()
        {
            // Call base class method to handle the file upload asynchronously
            ActionResult result = await base.HandleRequestAsync();
            return result;
        }
    }
}

Error should occur on this line

ActionResult result = await base.HandleRequestAsync();

Answer 1

The error is correct.

VS2010 with the Async CTP is not stable and certainly not recommended for production use. Please note that it is not easy to even create this development environment anymore, since the Async CTP is blocked by a number of Windows Updates.

But even if you use VS2012 (i.e., with Microsoft.Bcl.Async), this still won't work because async behavior is undefined on ASP.NET 4.

To use async on MVC, you must use ASP.NET 4.5 (or higher), and this means using VS2012.