Automapper - need to map a parent property when mapping children - automapper

Question

The basic problem is that I have properties on my source parent entities that I need to map to my destination child DTOs when the child entities are mapped to the destination child DTOs. The child entities do not have navigation properties to their parent. As you can see below, the parent has a field of the child type. You can see in the code below that ParentSource has a property called TitleImage of type ImageSource. So linkage is one directional. In my code, I use the ImageSource everywhere. There are at least 15 different entities with properties of type ImageSource. I normalized my database. The ImageSource entity does not have X and Y coordinates because only a few, maybe 5 out of 30, places actually need those extra values. In those few places, I added the X and Y on the parent as you see on the ParentSource class with the TitleImageX and TitleImageY.
I could easily do what I want with a loop, and that is what I am doing now, but I would love to use Automapper for this if I could. It would be way less code.
Here are my classes:
public class ParentSource
{
public string Id { get; set; }
public string Name { get; set; }
public ImageSource HomeImage { get; set; }
public ImageSource TitleImage { get; set; }
//These should be copied to the child object
public int TitleImageX { get; set; }
public int TitleImageY { get; set; }
}
public class ParentDest
{
public string ParentId { get; set; }
public string DisplayName { get; set; }
public ImageDest HomeImage { get; set; }
public ImageDest TitleImage { get; set; }
}
public class ImageSource
{
public string Id { get; set; }
public string Url { get; set; }
public decimal Height { get; set; }
public decimal Width { get; set; }
}
public class ImageDest
{
public string ImageId { get; set; }
public string ImageUrl { get; set; }
public decimal Height { get; set; }
public decimal Width { get; set; }
//Not all images have Coordinate
public decimal XCoordinate { get; set; }
public decimal YCoordinate { get; set; }
}
Here are what I have so far for doing the mappings. I don't know how to copy the X & Y coordinates from the parent to the child.
CreateMap<ParentSource, ParentDest>()
.ForMember(
dest => dest.ParentId,
opt => opt.MapFrom(src => src.Id))
.ForMember(
dest => dest.DisplayName,
opt => opt.MapFrom(src => src.Name));
CreateMap<ImageSource, ImageDest>()
.ForMember(
dest => dest.ImageId,
opt => opt.MapFrom(src => src.Id))
.ForMember(
dest => dest.ImageUrl,
opt => opt.MapFrom(src => src.Url));
Thank you for your time and help.

Answer 1

Or you can do it in config (not tried or tested) which you may prefer, but there is no check for null on TitleImage
CreateMap<ParentSource, ParentDest>()
.ForMember(
dest => dest.ParentId,
opt => opt.MapFrom(src => src.Id))
.ForMember(
dest => dest.DisplayName,
opt => opt.MapFrom(src => src.Name))
.ForMember(dest=>dest.TitleImage,
opt=>opt.MapFrom(src=>new ImageDest
{
Width = src.TitleImage.Width,
Height = src.TitleImage.Height,
ImageId = src.TitleImage.Id,
ImageUrl = src.TitleImage.Url,
XCoordinate = src.TitleImageX,
YCoordinate = src.TitleImageY
}
));

Answer 2

From what I gather you want the X&Y from the parent into the child. You can use a converter class for this.
Converter:
public class ParentConverter : ITypeConverter<ParentSource, ParentDest>
{
public ParentDest Convert(ParentSource source, ParentDest destination, ResolutionContext context)
{
if (destination == null)
destination = new ParentDest();
destination.DisplayName = source.Name;
destination.ParentId = source.Id;
if (source.TitleImage != null)
{
destination.TitleImage = context.Mapper.Map<ImageDest>(source.TitleImage);
destination.TitleImage.XCoordinate = source.TitleImageX;
destination.TitleImage.YCoordinate = source.TitleImageY;
}
return destination;
}
}
Mapping:
CreateMap<ParentSource, ParentDest>()
.ConvertUsing<ParentConverter>();
CreateMap<ImageSource, ImageDest>()
.ForMember(
dest => dest.ImageId,
opt => opt.MapFrom(src => src.Id))
.ForMember(
dest => dest.ImageUrl,
opt => opt.MapFrom(src => src.Url);
});