如何从平面实体映射到多个 DTO？

Question

我希望在 C# .NET Core 中使用 AutoMapper 从一个已经扁平化的实体映射到一组嵌套的 DTO。此外，DTO 具有一对多关系，扁平实体隐藏在结构中。例如：

public class Product
{
    public int Id { get; set; }
    public string Name { get; set; }
    public int Price { get; set; }
    public int Weight { get; set; }
}

public class ProductDto
{
    public string Name { get; set; }
    public IEnumerable<PriceDto> Prices { get; set; }
}

public class PriceDto
{
    public int Price { get; set; }
    public int Weight { get; set; }
}

我知道 AutoMapper 提供的 ReverseMap() 函数，但是考虑到我开始一个扁平的实体，我不确定如何建立两者之间的关系ProductDto 和 PriceDto。

编辑：这是我以 "Product" 的形式收到的一组扁平化数据示例。注意将需要的 ProductDto 和 PriceDto 之间的推断一对多关系。

+-----+-------+-------+--------+
| Id  | Name  | Price | Weight |
+-----+-------+-------+--------+
|   1 | "foo" |     8 |     12 |
|   2 | "foo" |    12 |     18 |
|   3 | "bar" |     3 |      1 |
|   4 | "bar" |     6 |      2 |
| ... |       |       |        |
+-----+-------+-------+--------+

Answer 1

我会定义两个域配置文件。一个用于 Product 到 ProductDto

CreateMap<Product, ProductDto>()
  .ForMember(x => x.Id , opts => opts.Ignore())
  .ForMember(x => x.Price , opts => opts.Ignore())
  .ForMember(x => x.Weight , opts => opts.Ignore())
  .ForMember(x => x.Name , opts => opts.MapFrom(y => y.Name));

还有一个用于 Product to PriceDto

CreateMap<Product, ProductDto>()
  .ForMember(x => x.Id , opts => opts.Ignore())
  .ForMember(x => x.Name , opts => opts.Ignore())
  .ForMember(x => x.Price , opts => opts.MapFrom(y => y.Price ))
  .ForMember(x => x.Weight , opts => opts.MapFrom(y => y.Weight ));

然后一次从同一个源映射到两个不同的目标。

Answer 2

您需要像下面这样实现自己的转换器：

ProductsConverter

public class ProductsConverter : ITypeConverter<List<Product>, List<ProductDto>>
{
    public List<ProductDto> Convert(List<Product> source, List<ProductDto> destination, ResolutionContext context)
    {
        return source.GroupBy(p => p.Name)
                    .Select(r => new ProductDto
                    {
                        Name = r.Key,
                        Prices =  source.Where(pp => pp.Name == r.Key)
                                                    .Select(rr => new PriceDto
                                                    {
                                                        Price = rr.Price,
                                                        Weight = rr.Weight
                                                    })
                    }).ToList();
    }
}

ModelProfile

public class ModelProfile: Profile
{
    public ModelProfile()
    {
        CreateMap<List<Product>, List<ProductDto>>()
            .ConvertUsing<ProductsConverter>();
    }
}

用例

public IActionResult Index()
{
    List<Product> products= new List<Product>() {
        new Product{ Id = 1, Name = "foo", Price = 8, Weight = 12},
        new Product{ Id = 2, Name = "foo", Price = 12, Weight = 18},
        new Product{ Id = 3, Name = "bar", Price = 3, Weight = 1},
        new Product{ Id = 4, Name = "bar", Price = 6, Weight = 2},
    };
    var result = _mapper.Map<List<ProductDto>>(products);
    return Ok(result);
}

如何从平面实体映射到多个 DTO？

How to map from a flat entity to more than one DTO?

c#

automapper

asp.net-core