public override string ToString()
{
var authors = string.Join("|", Authors.Select(e => e.Name));
var categories = string.Join('|', BookCategories.Select(e => e.Category.Name));
return($"Book {{ Id = {Id}, ISBN = {Identifier}, Title = {Title}, Language = {Language}, Authors = {authors}, Categories = {categories} }}");
}
private bool IsCategoryInList(Category category)
{
return(BookCategories.Select(e => e.Category).Contains(category));
}