CODEWITHSUNDEEP
c#
Evgeny Kachan
Evgeny Kachan

Reputation: 15

OrderBy List by another collection

Have some problem. Need to sort the list by another collection:

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

Class Books:

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; }
}

Class 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; }
}

Class Authors: 

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; }
}

How i can sort b by authors last name?

Upvotes: 0

Views: 76

Answers (1)

Keith
Keith

Reputation: 155692

Something like this, though with mutiple authors it remains a question which author you order by:

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

Alternatively you could apply some logic (if you had it)...

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

Upvotes: 4

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