Set parent properties when mapping?

Question

I have the following classes:

public class ParentDto
{
    public Guid Guid {get; set;}
    public IEnumerable<Child> Children {get; set;}

    public ParentDto() { Guid = Guid.NewGuid(); }
}

public class ChildDto
{
    public Guid Guid {get; set;}
    public Guid ParentGuid {get; set;}
    public IEnumerable<GrandChild> GrandChildren {get; set;}

    public ChildDto() { Guid = Guid.NewGuid(); }
}

public class GrandChildDto
{
    public Guid Guid {get; set;}
    public Guid ChildGuid {get; set;}

    public GrandChildDto() { Guid = Guid.NewGuid(); }
}

The mapping is simply:

Mapper.Initialize(cfg =>
{
  cfg.CreateMap<ParentModel, ParentDto>().ReverseMap();
  cfg.CreateMap<ChildModel, ChildDto>().ReverseMap();
  cfg.CreateMap<GrandChildModel, GrandChildDto>().ReverseMap();
});

Currently, I first do the mapping, then I do:

foreach (var child in parent.Children)
{
    child.ParentGuid = parent.Guid;

    foreach (var grandChild in child.GrandChildren)
    {
        grandChild.ChildGuid = child.Guid;
    }
}

This is because the Guid properties are only found in the DTO classes.

Is it possible to set the guids within the mapping configuration and avoid the foreach block?

Answer 1

AutoMapper does support execution code before and after map operations.

You can define them with code like this

cfg.CreateMap<Source, Target>()
   .AfterMap((src, dest) => { .. }); 

But you probably can use this only when your DTOs are depending on the ancestor-generation - eg ParentDto contains ChildDTO. Else the items are independent from each other and using AutoMapper could be way more complex, than just using foreaches.