BookManager.Web.Controllers.AdminController.UpdateBookCategory C# (CSharp) Метод

        private void UpdateBookCategory(int bookId, List<Genre> newCategories)
        {
            try
            {
                Book book = db.Books.Include("Categories").Single(b => b.BookId == bookId);

                foreach (var oldCategory in book.Categories.ToList())
                {
                    book.Categories.Remove(oldCategory);
                }

                foreach (var category in newCategories)
                {
                    book.Categories.Add(category);
                }
                db.SaveChanges();
            }
            catch { }
        }