PocketBook/Sources/VMWrapper/BookViewModel.cs

using Model;
using System.Collections.ObjectModel;

namespace VMWrapper
{
    public class BookViewModel
    {
        private readonly ILibraryManager data;

        public ObservableCollection<AuteurGroup> AuteurGroups { get; private set; } =
            new ObservableCollection<AuteurGroup>();

        public BookViewModel(ILibraryManager data)
        {
            this.data = data;
            LoadBooksAsync();
        }

        private async void LoadBooksAsync()
        {
            try
            {
                var (totalA, authors) = await data.GetAuthorsByName("", 0, 5);

                foreach (Author author in authors)
                {
                    var books = data.GetBooksByAuthor(author.Name, 0, 5).Result.Item2;
                    var observableBooks = new ObservableCollection<Book>(books);
                    AuteurGroups.Add(new AuteurGroup(author.Name, observableBooks));
                }
            }
            catch (Exception ex)
            {
                System.Diagnostics.Debug.WriteLine(ex.Message);
            }
        }

        public class AuteurGroup : ObservableCollection<Book>
        {
            public string Name { get; private set; }

            public AuteurGroup(string name, ObservableCollection<Book> books)
                : base(books)
            {
                Name = name;
            }
        }
    }
}