我們如何從C＃中的異步操作方法獲取值

Question

我有一個類似的async方法

[HttpPost]
public async Task<JsonResult> AddTwoIntegers(int param1, int param2)
{         
   var result = await (param1 + param2);
   return Json(new {finalValue: result}, JsonRequestBehavior.AllowGet)            
}

現在在另一個Action Method我正在調用此函數

public ActionResult SomeFunction(string userSettingsViewModel)
{          
      Task<JsonResult> jsonData = this.AddTwoIntegers(5,10);          

      jsonData.ContinueWith(task =>
      {
           JsonResult result = task.Result;
           if (result.Data.ToString() == "") {
                var data = result.Data;
           }            
      });

      // I want to retrieve the value returned and use that value in some operation.

      return Json("Success", JsonRequestBehavior.AllowGet);
}

我如何從Action Result獲取返回的值。

Answer 1

您需要更改方法以返回Task<ActionResult>並將其標記為async ，然后等待AddTwoIntegers()的結果...

public async Task<ActionResult> SomeFunction(string userSettingsViewModel)
{          

    JsonResult result = await this.AddTwoIntegers(5, 10);  
    var jsonData = result.data;

    // ...

    return Json("Success", JsonRequestBehavior.AllowGet);
}

為了完整起見，樣本方法應類似於以下內容：

[HttpPost]
public Task<JsonResult> AddTwoIntegers(int param1, int param2)
{         
   var result = param1 + param2;
   return Task.FromResult(Json(new {finalValue: result}, 
                               JsonRequestBehavior.AllowGet));            
}

Answer 2

應該是這樣的：

JsonResult = await AddTwoIntegers(5,10);

查看MSDN示例

Answer 3

然后，您需要聲明將結果存儲在操作外部的變量。 然后使用變量。

任務jsonData = this.AddTwoIntegers（5,10）;

   Type data = null; //Note that I put Type because I don't know your type for result.Data 
  jsonData.ContinueWith(task =>
  {
       JsonResult result = task.Result;
       if (result.Data.ToString() == "") {
             data = result.Data;
       }            
  });

  // I want to retrieve the value returned and use that value in some operation.
  //Now you can use your variable data here!!
  return Json("Success", JsonRequestBehavior.AllowGet);

}