从服务层返回包含多个实体的 DTO 对象

Question

我正在使用存储库模式开发一个 .net 多层应用程序。我的实现存储库模式的数据访问层具有将数据返回到服务层层的方法，服务层层又将数据返回到 Web api 层。目前我已经编写了返回客户信息或订单信息的方法。我还需要编写将返回 CustomerOrder 信息的方法。我认为最好的地方是把它写在服务层，但不知道如何去做。我在服务层中创建了一个 DTO 对象，其中包含来自 Customer 和 Order 类的字段。是服务层最好写这个逻辑的地方。我想我必须在服务层中填充 Dto 对象并将该对象返回到表示层。谁能给我指路。

实体层

 public class Customers
    {


        public int Id { get; set; }
        public string FirstName { get; set; }
        public string LastName { get; set; }
        public Gender Gender { get; set; }
        public string Email { get; set; }

        public Address Address { get; set; }

        public int AddressId { get; set; }


        public ICollection<Orders> Orders { get; set; }

    }
    public class Orders
    {
        public int Id { get; set; }

        public DateTime? OrderDate { get; set; }
        public int? OrderNumber { get; set; }

        public Customers Customers { get; set; }

        public int CustomerId { get; set; }

        public ICollection<ProductOrder> ProductOrders { get; set; }
    }

   public class Address
    {
        public int Id { get; set; }

        public string Address1 { get; set; }

        public string Address2 { get; set; }

        public string City { get; set; }

        public State State { get; set; }

        public int StateId { get; set; }


        public ICollection<Customers> Customers { get; set; }


        public string ZipCode { get; set; }
    }

数据访问层

 public class CustomerRepository : RepositoryBase<Customers>, ICustomerRepository
    {
        public CustomerRepository(IDbFactory dbFactory)
            : base(dbFactory) { }



        public IEnumerable<Customers> GetAllCustomers()
        {
            return (from customer in this.DbContext.Customers
                    select customer).ToList();
        }

    }

    public interface ICustomerRepository : IRepository<Customers>
    {
        IEnumerable<Customers> GetAllCustomers();

    }


 public class OrderRepository : RepositoryBase<Orders>, IOrderRepository
    {
        public OrderRepository(IDbFactory dbFactory)
            : base(dbFactory) {}

        public IEnumerable<Orders> GetAllOrders()
        {
            return (from order in this.DbContext.Orders
                    select order).ToList();
        }

    }

    public interface IOrderRepository : IRepository<Orders>
    {
        IEnumerable<Orders> GetAllOrders();
    }

服务层

    public interface ICustomerService
        {
            IEnumerable<Customers> GetCustomers();
        }

        public class CustomerService : ICustomerService
        {
            private readonly ICustomerRepository _customerRepository;
            private readonly IUnitOfWork _unitOfWork;

            public CustomerService(ICustomerRepository customerRepository, IUnitOfWork unitOfWork)
            {
                this._customerRepository = customerRepository;
                this._unitOfWork = unitOfWork;
            }


            public IEnumerable<Customers> GetCustomers()
            {
                return _customerRepository.GetAll();
            }




 public interface IOrderService
        {
            IEnumerable<Orders> GetOrders();

        }

        public class OrderService : IOrderService
        {
            private readonly IOrderRepository _orderRepository;
            private readonly IUnitOfWork _unitOfWork;

            public OrderService(IOrderRepository orderRepository, IUnitOfWork unitOfWork)
            {
                this._orderRepository = orderRepository;
                this._unitOfWork = unitOfWork;
            }
           }

            public IEnumerable<Orders> GetOrders()
            {
                return _orderRepository.GetAll();
            }
           }

服务层中的Dto对象

  public class CustomerDto
    {
        public int Id { get; set; }
        public string FirstName { get; set; }
        public string LastName { get; set; }
        public string Gender { get; set; }
        public string Email { get; set; }

    }



public class OrderDto
{
    public int Id { get; set; }
    public DateTime? OrderDate { get; set; }
    public int? OrderNumber { get; set; }
}
public class CustomerOrderDto
{
    public CustomerDto Customer { get; set; }
    public OrderDto Order { get; set; }

}

服务层中的映射（域对象到 Dto）

public class DomainToDtoMapping : Profile
{
    public override string ProfileName
    {
        get { return "DomainToDtoMapping"; }
    }

    [Obsolete]
    protected override void Configure()
    {
        CreateMap<Customers, CustomerDto>();
        CreateMap<Address, AddressDto>();
        CreateMap<Orders, OrderDto>();
        CreateMap<OrdersDetails, OrderDetailsDto>();
        CreateMap<State, StateDto>();


        CreateMap<CustomerDto, CustomerOrderDto>();
        CreateMap<AddressDto, CustomerOrderDto>();
        CreateMap<OrderDto, CustomerOrderDto>();
        CreateMap<OrderDetailsDto, CustomerOrderDto>();
        CreateMap<State, CustomerOrderDto>();

    }
}

Answer 1

您是否考虑过实施Composite Pattern？

您的CustomerOrderDto 将包含一个CustomerDto 和一个OrderDto 类。像这样：

public class CustomerOrderDto
{
    public CustomerDto Customer {get; set;}
    public OrderDto Order {get; set;}
}

实施此模式将带来以下优势：

1. 未来对CustomerDto 或OrderDto 的任何更改都将自动成为CustomerOrderDto 的一部分。
2. 将数据映射到dto 类的代码可以重复用于映射单个dto 实体以及“CustomerOrderDto”。

将实体类映射到 DTO 类的代码应该在您的服务层中。

将 Customer 实体映射到 CustomerDto 实体：

    internal static CustomerDto Map(Customer entity)
    {
        if (entity == null) throw new ArgumentNullException("entity");

        CustomerDto dto = new CustomerDto();
        try
        {
            dto.Id = entity.Id;
            dto.FirstName = entity.FirstName;
            dto.LastName = entity.LastName;
            dto.Gender = entity.Gender;
            dto.Email = entity.Email;
        }
        catch (Exception e)
        {
            string errMsg = String.Format("Map(entity). Error mapping a Customer entity to DTO. Id: {0}.", entity.Id);
            //LOG ERROR
        }

        return dto;
    }

您是否完成了用于检索复合 CustomerOrder 实体的存储库层？我看到您已经完成了 GetAllCustomers() 和 GetAllOrders() 的存储库代码。

Answer 2

试试这个：

public interface IOrderService
    {
        IEnumerable<CustomerOrderDto> GetOrders();
    }

 public IEnumerable<CustomerOrderDto> GetOrders()
    {
        List<CustomerOrderDto> customerOrderList = new List<CustomerOrderDto>();

        foreach (var item in customerOrderList)
        {
            CustomerOrderDto customerOrder = new CustomerOrderDto();
            //fields mapping

            customerOrderList.Add(customerOrder);
        }


        return customerOrderList;
    }

最好的映射方法是 linq 或 this。你不应该使用 Automapper，因为它太慢了。