Question

Backload示例＃4代码无法正常工作。

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;
    }
}

我收到此错误：

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

重现：

使用VS2010，打开新的MVC4项目。
要在VS2010中启用异步，请安装VS Async CTP：http://www.microsoft.com/en-us/download/details.aspx?id=9983
在您的项目中，参考：[VS Async CTP安装] \ Microsoft Visual Studio异步CTP \ Samples \ AsyncCtpLibrary.dll

使用程序包管理器命令

Install-Package Backload

从https://github.com/blackcity/Backload
打开示例＃4并从FileUploadController.cs复制FileUploadDerivedController类的代码。

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;

控制器

// 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;
        }
    }
}

此行应出现错误

ActionResult result = await base.HandleRequestAsync();

Answer 1

错误是正确的。

使用Async CTP的VS2010不稳定，当然不建议用于生产。请注意，甚至不再容易创建此开发环境，因为Async CTP被许多Windows更新阻止。

但即使你使用VS2012（即使用Microsoft.Bcl.Async），这仍然无效，因为async behavior is undefined on ASP.NET 4。

要在MVC上使用async，必须使用ASP.NET 4.5（或更高版本），这意味着使用VS2012。

Backload示例＃4在VS2010 MVC4中不起作用

1 个答案: