Thanks for the insights :)

I didn’t go too deep in FluentValidation to not make this article longer.

As for the ICollection, I avoid using virtual properties to make sure that I will not enable Lazy Loading. And I always initialize collections in the constructor too avoid getting a System.NullReferenceException and can . For example, if I create a new instance of Artist like below:

var a = new Artist();

without initializing Musics collection in the constructor, and try to add a new music to the list, even with the virtual key I will get an exception.

a.Musics.Add(new Music()); // Throws System.NullReferenceException

Or try to iterate throught for some reason:

foreach(var music in a.Musics)
{
    // run some code
}

Unless I assign a new list of musics to it, like this:

var musics = new Collection();
musics.Add(new Music());
a.Musics = musics;