AutoMapper inheritance and Linq

Question

I've been looking over how to use Inheritance in AutoMapper but I'm struggling to get it working fully with Linq. Here is my code:

I have defined my mappings here:

CreateMap<Article, ArticleDetailsViewModel>()
    .Include<Article, ArticleNewsItemDetailsViewModel();

CreateMap<Article, ArticleNewsItemDetailsViewModel>();

ArticleDetailsViewModel is a base class of ArticleNewsItemDetailsViewModel.

Now here lies the problem, if I had:

CreateMap<ArticleNewsItem, ArticleNewsItemDetailsViewModel>();

All of the properties in the view model would automatically map because they are the same name as their Linq object counterpart. However, because I am using the Article => ArticleNewsItemDetailsViewModel mapping this is not possible, instead I would have to define each one as:

.ForMember(x => x.Property1, opt => opt.MapFrom(src => src.ArticleNewsItem.Property1)

I thought about moving all properties from ArticleNewsItemDetailsViewModel into a new view model and having that class a property within the ArticleNewsItemDetailsViewModel and as long as there is a mapping between those two objects then it will work, but it doesn't feel very clean.

Is there any way to avoid having to do this?

Answer 1

Supposing you have the following classes:

    public class Article
    {
        public string Prop1 { get; set; }
        public string Prop2 { get; set; }
        public ArticleNewsItem ArticleNewsItem { get; set; }
    }

    public class ArticleDetailsViewModel
    {
        public string Prop1 { get; set; }
    }

    public class ArticleNewsItemDetailsViewModel : ArticleDetailsViewModel
    {
        public string Prop2 { get; set; }
        public string Prop3 { get; set; }
    }

    public class ArticleNewsItem
    {
        public string Prop3 { get; set; }
    }

The mapping should look like below:

var res = Mapper.Map<Article, ArticleNewsItemDetailsViewModel>(_article);
Mapper.Map(_article.ArticleNewsItem, res);

Moreover you can create custom type converter to avoid writing these two lines every time you need to map Article to ArticleNewsItemDetailsViewModel.