MVC 4 中的异步操作过滤器

问题描述

我有一个动作过滤器，当在某些特定条件下使用时，它必须执行网络服务调用以确保当前状态有效.这最初似乎是 async/await 的理想选择，但我遇到了一个障碍:

I have an action filter that when used in certain specific conditions has to perform a web service call to ensure that the current state is valid. This initially seemed like an ideal candidate for async/await, but I have encountered a snag:

假设一个请求到:/Test/FilteredAction

Assume a request to: /Test/FilteredAction

• MyCustomActionFilter 开始执行
  • 到达第一个await"语句

  传统上，我希望操作过滤器恢复执行，然后在控制器操作开始执行之前完成，但事实并非如此.

  Traditionally I would expect the action filter to resume executing and then complete before the controller action starts executing, but this does not happen.

  现在我假设这是因为我正在使用:

  Now I assume this is because I am using:

  public class MyCustomActionFilter : ActionFilterAttribute
  {
      public override **async** void OnActionExecuting(FilterContext context)
      {
          var foo = await WebServiceCall();
      }
  }
  

  所以我想我的问题是:MVC 4 中是否有一个异步感知动作过滤器类，或者我应该阻止这里的调用?

  So I think my question is: Is there an async-aware action filter class built into MVC 4, or should I just block on the calls in here?

  推荐答案

  MVC 没有与 async 兼容的操作过滤器(但 WebAPI 确实有一个).

  MVC does not have an async-compatible action filter (but WebAPI does have one).

  目前，我建议您在 OnActionExecuting 中使用阻塞调用.希望MVC在未来会有更好的故事.

  For now, I recommend you use blocking calls in OnActionExecuting. Hopefully MVC will have a better story in the future.

  更新:您可以在此处投票让 MVC 团队添加 async 过滤器.

  Update: You can vote here for the MVC team to add async filters.

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