Automapper：映射继承自 List 的两种类型<keyvaluepair<string, string> &gt;&gt; </keyvaluepair<string,>

Question

Let's assume I have these types:

public class MetadataList1 : List<KeyValuePair<string, string>>
{

}

public class MetadataList2 : List<KeyValuePair<string, string>>
{

}

I would like to be able to map one to the other with last version of Automapper (10.1.1):

var metadataList = _mapper.Map<MetadataList2>(metadataList1);

But list items are not copied, the resulting list always have a count of 0.

I tried the most naive configuration:

cfg.CreateMap<MetadataList1, MetadataList2>().ReverseMap();

And a few other things:

cfg.CreateMap<KeyValuePair<string, string>, KeyValuePair<string, string>>();
cfg.CreateMap<List<KeyValuePair<string, string>>, List<KeyValuePair<string, string>>>();
cfg.CreateMap<MetadataList1, MetadataList2>()
    .IncludeBase<List<KeyValuePair<string, string>>, List<KeyValuePair<string, string>>>()
    .ReverseMap();

I can't figure how to have it working, and I didn't find the answer, especially because Automapper configuration and usage seems to have changed several times these years regarding this kind of usage.

Answer 1

In general if you map two types with Automapper, collection mapping comes for free. Eg if I mapped type MyClass Automapper would map List<MyClass> without extra set up. However your type is itself a collection, and I guess Automapper does not find public properties to map there.

I would suggest to use a custom converter:

cfg.CreateMap<MetadataList1, MetadataList2>().ConvertUsing<MyConverter>();

public class MyConverter : ITypeConverter<MetadataList1, MetadataList2>
{
  public MetadataList1 Convert(MetadataList2 source, MetadataList1 destination, ResolutionContext context) 
  {
    // iterate over first list and copy elements to the second list
  }
}