通過另一個集合排序

Question

有問題 需要按另一個集合對列表進行排序：

List<Books> b = new List<Books>();

課堂書籍：

public partial class Books
{
    public Books()
    {
        this.BookAuthors = new HashSet<BookAuthors>();
    }

    public int BookID { get; set; }
    public string BookName { get; set; }

    public virtual ICollection<BookAuthors> BookAuthors { get; set; }
}

類BookAuthors：

public partial class BookAuthors
{
    public int Id { get; set; }
    public int AuthorID { get; set; }
    public int BookID { get; set; }

    public virtual Books Books { get; set; }
    public virtual Authors Authors { get; set; }
}

類作者：

public partial class Authors
{
    public Authors()
    {
        this.BookAuthors = new HashSet<BookAuthors>();
    }

    public int AuthorID { get; set; }
    public string FirstName { get; set; }
    public string LastName { get; set; }

    public virtual ICollection<BookAuthors> BookAuthors { get; set; }
}

我如何按作者姓氏對b進行排序？

Answer 1

像這樣的事情，盡管對於多位作者而言，仍然是一個問題，您可以通過以下哪種方式訂購哪位作者：

var sorted = 
    from book in b
    let firstAuthor = book.BookAuthors.First()
    let lastName = firstAuthor.LastName
    order book by lastName 
    select book

或者，您可以應用一些邏輯（如果有的話）...

var sorted = 
    from book in b
    let author = book.BookAuthors.FirstOrDefault(a=>a.Primary) ?? 
        book.BookAuthors.FirstOrDefault(a=>a.Editor) ??
        book.BookAuthors.First()
    let lastName = author.LastName
    order book by lastName 
    select book