AutoMapper - 使用嵌套将不同类型的集合映射到另一种类型的集合

Question

我目前正在努力使用 AutoMapper 版本 10.1.1 配置。 我有以下类型：

class Response
{
    List<Assignment> Assignments { get; }
    List<Product> Products { get; }
}

class Assignment
{
    int AssignmentId { get; set; }
    int ProductId { get; set; } // references Product.ProductId
}

class Product
{
    int ProductId { get; set; }
}

class AssignmentModel
{
    int AssignmentId { get; set; }
    int ProductId { get; set; }
    Product Product { get; set; }
}

对于响应对象的“Assignments”属性中的每个项目，我想根据产品 ID 获取一个具有相应产品的新 AssignmentModel。

当前的解决方案通过将Assignments 映射到新的AssignmentModels 并将Products 映射到现有的AssignmentModels 来工作。缺点是，我必须调用映射器两次。

cfg.CreateMap<Assignment, AssignmentModel>();
cfg.CreateMap<Product, AssignmentModel>()
    .ForMember(
        d => d.Product, opt => opt.MapFrom(s => s))
    .EqualityComparison((s, d) => s.ProductId == d.ProductId)
    .ForAllOtherMembers(opt => opt.Ignore());

var assignments = mapper.Map<ICollection<AssignmentModel>>(response.Assignments);
mapper.Map(response.Products, assignments); // not using the result because it does not return assignments without products
return assignments;

是否有可能在一个电话中做到这一点？像这样：

return mapper.Map<ICollection<AssignmentModel>>(response);

Answer 1

建议在您的场景中使用Custom Type Resolver。

映射配置/配置文件

cfg.CreateMap<Assignment, AssignmentModel>();
            
cfg.CreateMap<Response, ICollection<AssignmentModel>>()
    .ConvertUsing<ResponseAssignmentModelCollectionConverter>();

在自定义类型转换器中：

1. source.Assignments 映射到 List<AssignmentModel>。
2. 使用 LINQ .Join() 将结果从1和source.ProductsProductId。

   public class ResponseAssignmentModelCollectionConverter : ITypeConverter<Response, ICollection<AssignmentModel>>
   {
       public ICollection<AssignmentModel> Convert(Response source, ICollection<AssignmentModel> destination, ResolutionContext context)
       {
           var _mapper = context.Mapper;
   
           var result = _mapper.Map<List<AssignmentModel>>(source.Assignments);
           result = result.Join(source.Products, 
           a => a.ProductId, 
           b => b.ProductId, 
           (a, b) =>
           {
               a.Product = b;
               return a;
           })
           .ToList();
   
           return result;
       }
   }
   

   mapper.Map<ICollection<AssignmentModel>>(response);
   

   Sample Demo on .NET Fiddle