用lambda表達式計算記錄數

Question

我有一個ASP.NET MVC4項目與實體框架。

如何到計數（帶有lambda表達式）請求的數量相關的MaterialPackingID = 123？

這裏是我的課：

public class Request 
{ 
    [Key] 
    public virtual int RequestID { get; set; } 
    public virtual ICollection<TransportedMaterial> TransportedMaterials { get; set; } 
} 

public class TransportedMaterial 
{ 
    [Key] 
    public int TransportedMaterialID { get; set; }     
    public MaterialPacking MaterialPacking { get; set; } 
} 


public class MaterialPacking 
{ 
    public int MaterialPackingID { get; set; } 
    public string DescriptionFr { get; set; } 
    public string DescriptionNl { get; set; } 
} 

所以：

• 1請求可能包含幾個TransportedMaterial

• 1 TransportedMaterial包含1 MaterialPacking

以下是我的嘗試：

public int CountExistingRequestsFilterByMaterialPacking(int id) 
    { 
     using (var unitOfWork = UnitOfWorkFactory.Create()) 
     { 
      var requestRepository = unitOfWork.Create<Request>(); 
      var materialPackingRepository = unitOfWork.Create<MaterialPacking>(); 
      var materialPacking = materialPackingRepository.SingleOrDefault(x => x.MaterialPackingID == id); 

      if (materialPacking == null) 
       throw new FaultException("Packing not found"); 

      return requestRepository.GetAll().Where(x => x..... == materialPacking.MaterialPackingID).Count(); 
     } 
    } 

謝謝。

Answer 1

做這樣的工作？

return requestRepository.GetAll().Count(req => 
    req.TransportedMaterials.Any(tm => 
     tm.MaterialPacking.MaterialPackingID == materialPacking.MaterialPackingID) 
    ); 

假設：你要包含有MaterialPackingID匹配一個一個或多個TransportedMaterial對象請求的計數你有興趣在沒有你已經嘗試用什麼方式什麼不行