嘗試在DocumentDB中創建文檔時獲取「任務已取消」

Question

當我嘗試使用以下代碼在DocumentDB數據庫中創建文檔時，代碼會在我調用CreateDocumentAsync（）的地方掛起並最終給我「任務被取消「錯誤。

任何想法爲什麼？

public static async Task<Employee> CreateEmployee(Employee emp) 
{ 
    try 
    { 
     using (client = new DocumentClient(new Uri(endPointUrl), authorizationKey)) 
     { 
     //Get the database 
     var database = await GetDatabaseAsync(); 

     //Get the Document Collection 
     var collection = await GetCollectionAsync(database.SelfLink, "Employees"); 

     await client.CreateDocumentAsync(collection.SelfLink, emp); 

     // Do something else with employee 
     } 
    } 
    catch 
    { 
     // Handle error 
    } 

    return emp; 
} 

P.S.爲簡潔起見，我沒有包含GetDatabaseAsync（）和GetCollectionsAsync（）部分的代碼。請注意，員工文檔是在我的數據庫中創建的。所以，這段代碼明確地連接到DocumentDB數據庫，查找集合並創建文檔。

只是不確定它爲什麼掛起並最終返回錯誤。

*****更新******

下面是錯誤的詳細信息： 任務被取消。

描述：執行當前Web請求期間發生未處理的異常。請查看堆棧跟蹤以獲取有關該錯誤的更多信息以及源代碼的位置。

異常詳細信息：System.Threading.Tasks.TaskCanceledException：任務被取消。 源錯誤：

HttpResponseMessage response = await client.PostAsJsonAsync("api/hr/register", employee); 

堆棧跟蹤：

[TaskCanceledException: A task was canceled.] 
    System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) +10915395 
    System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) +52 
    System.Runtime.CompilerServices.TaskAwaiter`1.GetResult() +24 
    ConsumerWebApi.Controllers.<Index>d__0.MoveNext() in c:\Users\Sam\Documents\Visual Studio 2013\Projects\ConsumerWebApi\ConsumerWebApi\Controllers\HomeController.cs:36 
    System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw() +22 
    System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) +10915367 
    System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) +52 
    System.Runtime.CompilerServices.TaskAwaiter.GetResult() +21 
    System.Threading.Tasks.TaskHelpersExtensions.ThrowIfFaulted(Task task) +61 
    System.Web.Mvc.Async.TaskAsyncActionDescriptor.EndExecute(IAsyncResult asyncResult) +114 
    System.Web.Mvc.Async.<>c__DisplayClass37.<BeginInvokeAsynchronousActionMethod>b__36(IAsyncResult asyncResult) +66 
    System.Web.Mvc.Async.WrappedAsyncResult`1.CallEndDelegate(IAsyncResult asyncResult) +47 
    System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +135 
    System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +102 
    System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeActionMethod(IAsyncResult asyncResult) +49 
    System.Web.Mvc.Async.AsyncInvocationWithFilters.<InvokeActionMethodFilterAsynchronouslyRecursive>b__3d() +117 
    System.Web.Mvc.Async.<>c__DisplayClass46.<InvokeActionMethodFilterAsynchronouslyRecursive>b__3f() +323 
    System.Web.Mvc.Async.<>c__DisplayClass33.<BeginInvokeActionMethodWithFilters>b__32(IAsyncResult asyncResult) +44 
    System.Web.Mvc.Async.WrappedAsyncResult`1.CallEndDelegate(IAsyncResult asyncResult) +47 
    System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +135 
    System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +102 
    System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeActionMethodWithFilters(IAsyncResult asyncResult) +50 
    System.Web.Mvc.Async.<>c__DisplayClass2b.<BeginInvokeAction>b__1c() +72 
    System.Web.Mvc.Async.<>c__DisplayClass21.<BeginInvokeAction>b__1e(IAsyncResult asyncResult) +185 
    System.Web.Mvc.Async.WrappedAsyncResult`1.CallEndDelegate(IAsyncResult asyncResult) +42 
    System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +132 
    System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +56 
    System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeAction(IAsyncResult asyncResult) +40 
    System.Web.Mvc.Controller.<BeginExecuteCore>b__1d(IAsyncResult asyncResult, ExecuteCoreState innerState) +34 
    System.Web.Mvc.Async.WrappedAsyncVoid`1.CallEndDelegate(IAsyncResult asyncResult) +70 
    System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +138 
    System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +59 
    System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +40 
    System.Web.Mvc.Controller.EndExecuteCore(IAsyncResult asyncResult) +44 
    System.Web.Mvc.Controller.<BeginExecute>b__15(IAsyncResult asyncResult, Controller controller) +39 
    System.Web.Mvc.Async.WrappedAsyncVoid`1.CallEndDelegate(IAsyncResult asyncResult) +62 
    System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +138 
    System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +59 
    System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +40 
    System.Web.Mvc.Controller.EndExecute(IAsyncResult asyncResult) +39 
    System.Web.Mvc.Controller.System.Web.Mvc.Async.IAsyncController.EndExecute(IAsyncResult asyncResult) +39 
    System.Web.Mvc.MvcHandler.<BeginProcessRequest>b__5(IAsyncResult asyncResult, ProcessRequestState innerState) +39 
    System.Web.Mvc.Async.WrappedAsyncVoid`1.CallEndDelegate(IAsyncResult asyncResult) +70 
    System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +138 
    System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +59 
    System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +40 
    System.Web.Mvc.MvcHandler.EndProcessRequest(IAsyncResult asyncResult) +40 
    System.Web.Mvc.MvcHandler.System.Web.IHttpAsyncHandler.EndProcessRequest(IAsyncResult result) +38 
    System.Web.CallHandlerExecutionStep.OnAsyncHandlerCompletion(IAsyncResult ar) +129 

Answer 1

這個問題是沒有取得異步調用導致右。我錯誤地調用了一個異步方法，即CreateDocumentAsync（）。

我發佈了一個關於異步編程的單獨問題，我得到的答案幫助我排除了這個問題。以下是該帖子： Want to understand async