public override void SaveChanges() { foreach (var artist in Artists) { if (artist.Id == 0) { artist.Id = Artists.Max(x => x.Id) + 1; } } foreach (var album in Albums) { if (album.Id == 0) { album.Id = Albums.Max(x => x.Id) + 1; } } foreach (var track in Tracks) { if (track.Id == 0) { track.Id = Tracks.Max(x => x.Id) + 1; } } }