Question

我有一个带有Entity Framework的ASP.NET MVC4项目。

如何计算（带有lambda表达式）相关MaterialPackingID = 123的Request数量？

以下是我的课程：

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请求可能包含多个TransportedMaterial
1 TransportedMaterial包含1个MaterialPacking

以下是我的尝试：

    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();
        }
    }

感谢。

Answer 1

这样的事情有用吗？

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

假设：您需要包含一个或多个TransportedMaterial对象的请求计数，这些对象的MaterialPackingID与您感兴趣的对象相匹配。

使用lambda表达式计算记录数

1 个答案: