Automapper merge/combine mappings

Question

Let's assume I have these mappings:

var mapping1 = Mapper.CreateMap<Order, BaseDto>()
    .ForMember(o => o.Referrer, m => m.Ignore());

var mapping2 = Mapper.CreateMap<Order, DetailDto>()
    .ForMember(o => o.Price, m => m.Ignore());

var mapping3 = Mapper.CreateMap<Order, UpdateDto>()
    .ForMember(o => o.Temp, m => m.Ignore());

Inheritance of Dtos:

DetailDto : BaseDto

UpdateDto : BaseDto

Is there any way to merge/combine the first mapping into mapping2 and mapping3?

Something like this:

var mapping1 = Mapper.CreateMap<Order, BaseDto>()
    .ForMember(o => o.Referrer, m => m.Ignore());

var mapping2 = Mapper.CreateMap<Order, DetailDto>()
    .Import(mapping1);
    .ForMember(o => o.Price, m => m.Ignore());

var mapping3 = Mapper.CreateMap<Order, UpdateDto>()
    .Import(mapping1);
    .ForMember(o => o.Temp, m => m.Ignore());

The .Include function does not seem to do what I want as the following doesn't work:

var mapping1 = Mapper.CreateMap<Order, BaseDto>()
    .Include<Order, DetailDto>()
    .Include<Order, UpdateDto>()
    .ForMember(o => o.Referrer, m => m.Ignore());

var mapping2 = Mapper.CreateMap<Order, DetailDto>()
    .ForMember(o => o.Price, m => m.Ignore());

var mapping3 = Mapper.CreateMap<Order, UpdateDto>()
    .ForMember(o => o.Temp, m => m.Ignore());

Update: Edited question to be more specific

And why can't you just do: var mapping1 = Mapper.CreateMap() .ForMember(o => o.Referrer, m => m.Ignore()).ForMember(o => o.Price, m => m.Ignore());? — Icarus, Jan 04 '13 at 10:11
@Icarus It is a bit more complicated, because the mappings have different destinations. I updated the question. — Dennis, Jan 04 '13 at 10:23

score 0 · Answer 1 · answered Jan 05 '13 at 06:52

I wonder if its a bug. The documentation states:

In AutoMapper 2.0, this becomes:
Mapper.CreateMap<Order, OrderDto>()
  .Include<OnlineOrder, OnlineOrderDto>()
  .Include<MailOrder, MailOrderDto>()
  .ForMember(o=>o.Id, m=>m.MapFrom(s=>s.OrderId));
Mapper.CreateMap<OnlineOrder, OnlineOrderDto>();
Mapper.CreateMap<MailOrder, MailOrderDto>();
Because we have defined the mapping for the base class, we no longer have to define it in the child mappings.

I have just upgraded to AutoMapper 2.2.1-ci9000 and I'm getting the same behaviour as you (ie, Referrer is not being ignored).

I suggest you create an issue for it and see what they say.

score 0 · Answer 2 · answered Jul 23 '14 at 14:06

I realise this comes a bit late, but for the benefit of someone else with similar issues...

I struggled with the same problem until I found this page on the AutoMapper Github wiki.

In summary:

Inherited configuration is evaluated against priorities (to resolve issues where multiple maps have conflicting configuration for the same members). An Ignore() that is inherited has a lower priority than AutoMapper's standard convention-based mapping. So where the source and destination types both have a Referrer property, the convention-based mapping for the most derived types overrides the inherited Ignore().

That suggests then, that in this instance, you need to repeat the Ignore() for the maps for each type derived from BastDto

Automapper merge/combine mappings

2 Answers2