public List <Album> CreateAlbumList() { List <Album> albums = new List <Album>(); List <Music> musics = musicService.GetAll(); HashSet <String> albumNames = new HashSet <String>(); foreach (Music music in musics) { albumNames.Add(music.Album); } foreach (String albumName in albumNames) { List <Music> albumMusics = musicService.GetAllByAlbum(albumName); Album album = new Album(albumMusics[0].Album, albumMusics); albums.Add(album); } return(albums); }