AutoMapper使用简单总结

近期，在用AutoMapper整理一些模型对象映射，顺便小结一下使用的体会。难免有写得不对的地方，谢谢指出！

1. AutoMapper是一个.NET的对象映射工具，可以方便地进行对象间的赋值处理.

项目地址：https://github.com/AutoMapper/AutoMapper。

帮助文档：https://github.com/AutoMapper/AutoMapper/wiki

2. Demo中使用到的类

public class Order
    {
        public int Id { get; set; }
        public Decimal? TotalAmount { get; set; }
        public bool? IsEnable { get; set; }

        public OrderDetail OrderDetaiEntity { get; set; }

        public List<ProductDetail> ProductList { get; set; }
    }

    public class OrderDetail
    {
        public string Remark { get; set; }

        public DateTime? OrderDate { get; set; }
        public string OrderUser { get; set; }
        public DateTime? ClosedDate { get; set; }

    }

    public class ProductDetail
    {
        public int? Id { get; set; }
        public string ProductName { get; set; }
        public Decimal? Price { get; set; }
    }

    public class OrderDto
    {
        public int Id { get; set; }
        public Decimal TotalAmount { get; set; }
        public bool IsEnable { get; set; }

        public string Remark { get; set; }

        public OrderDetailDto OrderDetaiEntity { get; set; }

        public List<ProductDetailDto> ProductList { get; set; }
    }

    public class OrderDetailDto
    {
        public DateTime OrderDate { get; set; }
        public string OrderUser { get; set; }
        public DateTime? ClosedDate { get; set; }
    }

    public class ProductDetailDto
    {
        public int? Id { get; set; }
        public string ProductName { get; set; }
        public Decimal? Price { get; set; }
    }

2. 对象映射情况

(1) 属性类型和名称相同的对象之间直接映射

Mapper.CreateMap<ProductDetail, ProductDetailDto>();
ProductDetail product = new ProductDetail(){ //赋值 };
ProductDetailDto productDto = Mapper.Map<ProductDetail,ProductDetailDto>(product);

(2) 对象之间属性转换、属性忽略

 Mapper.CreateMap<Order, OrderDto>()
              .ForMember(dest => dest.Id, opt => opt.MapFrom(src => src.Id))
              .ForMember(dest => dest.TotalAmount, opt => opt.MapFrom(src => src.TotalAmount ?? 0))
              .ForMember(dest => dest.IsEnable, opt => opt.MapFrom(src => src.IsEnable ?? false))
              .ForMember(dest => dest.Remark, opt => opt.MapFrom(src => src.OrderDetaiEntity.Remark))
              .ForMember(dest => dest.OrderDetaiEntity, opt => opt.Ignore())
              .ForMember(dest => dest.ProductList, opt => opt.Ignore());
OrderDto orderDto1 = Mapper.Map<Order, OrderDto>(orderObj);

(3)属性填充固定值

 Mapper.CreateMap<OrderDetail, OrderDetailDto>()
                .ForMember(dest => dest.OrderDate, opt => opt.UseValue<DateTime>(DateTime.Now));

(4)包含子对象的对象映射，需要先映射子对象

 Mapper.CreateMap<OrderDetail, OrderDetailDto>()
                .ForMember(dest => dest.OrderDate, opt => opt.UseValue<DateTime>(DateTime.Now));
         Mapper.CreateMap<ProductDetail, ProductDetailDto>();

         Mapper.CreateMap<Order, OrderDto>()
              .ForMember(dest => dest.Id, opt => opt.MapFrom(src => src.Id))
              .ForMember(dest => dest.TotalAmount, opt => opt.MapFrom(src => src.TotalAmount ?? 0))
              .ForMember(dest => dest.IsEnable, opt => opt.MapFrom(src => src.IsEnable ?? false))
              .ForMember(dest => dest.Remark, opt => opt.MapFrom(src => src.OrderDetaiEntity.Remark));

或者可以这样写

Mapper.CreateMap<ProductDetail, ProductDetailDto>();

            var exp = Mapper.CreateMap<Order, OrderDto>()
              .ForMember(dest => dest.Id, opt => opt.MapFrom(src => src.Id))
              .ForMember(dest => dest.TotalAmount, opt => opt.MapFrom(src => src.TotalAmount ?? 0))
              .ForMember(dest => dest.IsEnable, opt => opt.MapFrom(src => src.IsEnable ?? false))
              .ForMember(dest => dest.Remark, opt => opt.MapFrom(src => src.OrderDetaiEntity.Remark));
              //映射子对象
            exp.ForMember(dest => dest.OrderDetaiEntity, opt => opt.MapFrom(dto => new OrderDetailDto() {
                OrderDate = DateTime.Now,
                OrderUser = dto.OrderDetaiEntity.OrderUser,
                ClosedDate = dto.OrderDetaiEntity.ClosedDate
            }));

或者也可以这样写

Mapper.CreateMap<OrderDetail, OrderDetailDto>()
               .ForMember(dest => dest.OrderDate, opt => opt.UseValue<DateTime>(DateTime.Now));
            Mapper.CreateMap<ProductDetail, ProductDetailDto>();

            Mapper.CreateMap<Order, OrderDto>()
              .ForMember(dest => dest.Id, opt => opt.MapFrom(src => src.Id))
              .ForMember(dest => dest.TotalAmount, opt => opt.MapFrom(src => src.TotalAmount ?? 0))
              .ForMember(dest => dest.Remark, opt => opt.Ignore())
              .ForMember(dest => dest.IsEnable, opt => opt.Ignore())
              //包含多个相同子对象时
              .ForMember(dest => dest.OrderDetaiEntity, opt => opt.MapFrom(src =>
                        Mapper.Map<OrderDetail, OrderDetailDto>(src.OrderDetaiEntity)
                  ));

(5）转化存在的对象

 Mapper.CreateMap<OrderDetail, OrderDetailDto>()
               .ForMember(dest => dest.OrderDate, opt => opt.UseValue<DateTime>(DateTime.Now));
            Mapper.CreateMap<ProductDetail, ProductDetailDto>();

            Mapper.CreateMap<Order, OrderDto>()
              .ForMember(dest => dest.Id, opt => opt.MapFrom(src => src.Id))
              .ForMember(dest => dest.TotalAmount, opt => opt.MapFrom(src => src.TotalAmount ?? 0))
              .ForMember(dest => dest.Remark, opt => opt.Ignore())
              .ForMember(dest => dest.IsEnable, opt => opt.Ignore());

            var orderDto4 = new OrderDto() { Remark = "this is default value.", IsEnable = true };
            Mapper.Map<Order, OrderDto>(orderObj, orderDto4);

(6)其他的, 通过自定义转化来实现

如可以实现 TypeConverter， ValueResolver，ValueFormatter 抽象方法.