等待返回任務完成

-1

之前，我有這樣的異步代碼等待返回任務完成

private async Task<InvalidInvoiceViewModel> ValidateInsertedDataInRawTables(string uploadPath, long batchId) 
    { 
     var direcotryPath = Path.Combine(uploadPath, batchId.ToString()); 
     var allFiles = Directory.GetFiles(direcotryPath); 
     var invoiceRawList = new List<InvoiceRaw>(); 
     var invoiceDetailRawList = new List<InvoiceDetailRaw>(); 
     await Task.Run(() => allFiles.ToList().ForEach(async file => 
     { 
      var fileName = Path.GetFileNameWithoutExtension(file); 
      switch (fileName) 
      { 
       case "invoice": 
        invoiceRawList = await ValidateInsertedDataInRawTablesForInvoiceAsync(batchId); 
        break; 
       case "invoicedetails": 
        invoiceDetailRawList = await ValidateInsertedDataInRawTablesForInvoiceDetailAsync(batchId); 
        break; 
      } 
     })); 
     var invalidInvoiceViewModel = new InvalidInvoiceViewModel 
     { 
      InvoiceRawList = invoiceRawList , 
      InvoiceDetailRawList = invoiceDetailRawList 
     }; 
     return invalidInvoiceViewModel; 
    }

但發生的事情是，在我總是得到0計數在InvoiceRawList和InvoiceDetailRawList兩者。我發現該方法返回之前異步lambda完成其處理。（在Chrome控制檯中，結果出現在網絡選項卡中，但在此之後會觸發ValidateInsertedDataInRawTablesForInvoiceAsync中的調試點）。我正在等待爲此lambda創建的Task.Run。我在這裏做錯了什麼？評論

如果我這樣做，以後

更新，它不會編譯，我把它改成...

private async Task<InvalidInvoiceViewModel> ValidateInsertedDataInRawTables(string uploadPath, long batchId) { var direcotryPath = Path.Combine(uploadPath, batchId.ToString()); var allFiles = Directory.GetFiles(direcotryPath); var invoiceRawList = new List<InvoiceRaw>(); var invoiceDetailRawList = new List<InvoiceDetailRaw>(); await Task.Run(async() => await allFiles.ToList().ForEach(async file => { var fileName = Path.GetFileNameWithoutExtension(file); switch (fileName) { case "invoice": invoiceRawList = await ValidateInsertedDataInRawTablesForInvoiceAsync(batchId); break; case "invoicedetails": invoiceDetailRawList = await ValidateInsertedDataInRawTablesForInvoiceDetailAsync(batchId); break; } })); var invalidInvoiceViewModel = new InvalidInvoiceViewModel { InvoiceRawList = invoiceRawList , InvoiceDetailRawList = invoiceDetailRawList }; return invalidInvoiceViewModel; }

，並說不能等待無效。我知道這意味着什麼，但是我該如何解決這個問題？ List.ForEach是一個無效的方法。

來源

2017-04-20 Razort4x

您並未等待您的ForEach循環體，它也是異步的。 – Evk

並**每個**文件設置invoiceRawList和invoiceDetailRawList –

@Evk：我做到了，但現在它甚至不會編譯！ – Razort4x

如果你想在裏面使用await，你將不得不使用普通的foreach循環。

private async Task<InvalidInvoiceViewModel> ValidateInsertedDataInRawTables(string uploadPath, long batchId) 
    { 
     var direcotryPath = Path.Combine(uploadPath, batchId.ToString()); 
     var allFiles = Directory.GetFiles(direcotryPath); 
     var invoiceRawList = new List<InvoiceRaw>(); 
     var invoiceDetailRawList = new List<InvoiceDetailRaw>(); 
     await Task.Run(async() => 
     { 
      foreach(var file in allFiles) 
      { 
       var fileName = Path.GetFileNameWithoutExtension(file); 
       switch (fileName) 
       { 
        case "invoice": 
         invoiceRawList = await ValidateInsertedDataInRawTablesForInvoiceAsync(batchId); 
         break; 
        case "invoicedetails": 
         invoiceDetailRawList = await ValidateInsertedDataInRawTablesForInvoiceDetailAsync(batchId); 
         break; 
       } 
      } 
     }); 
     var invalidInvoiceViewModel = new InvalidInvoiceViewModel 
     { 
      InvoiceRawList = invoiceRawList, 
      InvoiceDetailRawList = invoiceDetailRawList 
     }; 
     return invalidInvoiceViewModel; 
    }

順便說一句，這個代碼並沒有太大的意義，要創建invoiceRawList和invoiceDetailRawList只是以取代他們在循環的每次迭代。

來源

2017-04-20 09:04:38

我知道，但是我們只會在每個文件夾中總是有2個文件，'invoice'和'invoicedetails'。 – Razort4x

然後重寫你的代碼，這是一個事實，而不是幸運的拍攝 –

Validate ...方法如何知道要處理的文件？你只需將batchId傳遞給他們。似乎是非常脆弱的結構 –

您實際上想等待所有內部任務完成時。

Task.WhenAll是你在這種情況下的朋友。

private async Task<InvalidInvoiceViewModel> ValidateInsertedDataInRawTables(string uploadPath, long batchId) 
{ 
    var direcotryPath = Path.Combine(uploadPath, batchId.ToString()); 
    var allFiles = Directory.GetFiles(direcotryPath); 
    var invoiceRawList = new List<InvoiceRaw>(); 
    var invoiceDetailRawList = new List<InvoiceDetailRaw>(); 

    List<Task> tasks = allFiles.Select(file => Task.Run(async() =>  
    { 
     var fileName = Path.GetFileNameWithoutExtension(file); 
     switch (fileName) 
     { 
      case "invoice": 
       invoiceRawList = await ValidateInsertedDataInRawTablesForInvoiceAsync(batchId); 
       break; 
      case "invoicedetails": 
       invoiceDetailRawList = await ValidateInsertedDataInRawTablesForInvoiceDetailAsync(batchId); 
       break; 
     } 
    })).ToList(); 

    await Task.WhenAll(tasks); 

    var invalidInvoiceViewModel = new InvalidInvoiceViewModel 
    { 
     InvoiceRawList = invoiceRawList, 
     InvoiceDetailRawList = invoiceDetailRawList 
    }; 
    return invalidInvoiceViewModel; 
}

來源

2017-04-20 09:16:46 Aron

等待返回任務完成

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