Automapper ResolveUsing cause "Can't resolve this to Queryable Expression"

Question

I'm using autommaper to map domain classes to model classes and viceversa. I need to encrypt/decrypt one property. When I map Model to Domain there isn't problem, work perefectly:

Mapper.CreateMap<EntityModel, Entity>().ForMember(dest => dest.Password, opt => opt.ResolveUsing(src => this.EncryptString(src.Password)))

But when map Entity to Model automapper crash and throws "Can't resolve this to Queryable Expression":

Mapper.CreateMap<Entity, EntityModel>().ForMember(dest => dest.Password, opt => opt.ResolveUsing(src => this.DecryptString(src.Password)))

I've tried with a Custom Value Resolver too, with same result:

Mapper.CreateMap<Entity, EntityModel>().ForMember(dest => dest.Password, op => op.ResolveUsing<PasswordResolver>().FromMember(x => x.Password));


public class PasswordResolver : ValueResolver<object, string>
{
        protected override string ResolveCore(object source)
    {
        return "TEST";
    }

}

Answer 1

As the documentation states, you can't use custom resolvers in queryable expressions:

https://github.com/AutoMapper/AutoMapper/wiki/Queryable-Extensions#supported-mapping-options

You can, however, use MapFrom:

Mapper.CreateMap<Entity, EntityModel>()
    .ForMember(dest => dest.Password, op => op.MapFrom(src => "TEST"));

I'm guessing that's not actually what you want to do for that Password property but that's how you can fix the example.