AutoMapper和条件映射为null

Question

I want to create mapping like this:

• if the source property has it's Id == 0, set the destination property to null

• if the source property has it's Id != 0, map this property using default configuration

For example:

Mapper.CreateMap<ItemViewModel, Item>()
    .ForMember(x => x.DestinationArticle, o => o.SetNullIfSourceHasIdZero(x => x.SourceArticle));

The DestinationArticle and SourceArticle properties are of implementing:

public interface IEntity
{
    long Id { get; set }
}

My current solution is this:

.ForMember(x => x.DestinationArticle, o => o.MapFrom(x => x.SourceArticle != null && x.SourceArticle.Id != 0 ? Mapper.Map<Article>(x.SourceArticle) : null))

which is not so good and not generic.

So, is there any way to create, mentioned before, SetNullIfSourceHasIdZero extension method or something, which could make my life easier?

Answer 1

Try something along these lines..

Mapper.CreateMap<ItemViewModel, Item>()
    .ForMember(x => x.DestinationArticle, opt => opt.ResolveUsing<SetNullIfSourceHasIdZero>());

public class SetNullIfSourceHasIdZero : ValueResolver<ItemViewModel, DestinationArticle>
{
     protected override DestinationArticle ResolveCore(ItemViewModel item)
     {
        // logic here            
     }
}