linq entityframework從連接表中得到結果

Question

我想寫一個Linq返回加入3個表的結果

有'書'，'作者'實體。 1書可以有許多作者和1作者可以寫很多書

我想要一個'BooksAuthors'具有書名和書的作者列表的對象。我現在的LINQ（但它返回任何結果，我得到空指針異常）

BooksAuthors = db.tblBooks.SelectMany(
        book => book.Authors, 
        (book, author) => new Books 
        { 
         BookID = book.BookID, 
         BookName = book.BookName, 
         Authors = book.Authors 
        }), 

其他類：

public class Author 
{ 
    public virtual int AuthorID { get; set; } 
    public virtual string AuthorName { get; set; } 
    public virtual ICollection<Book> Books { get; set; } 
} 
public class Book 
{ 
    public virtual int BookID { get; set; } 
    public virtual string BookName { get; set; } 
    public virtual ICollection<Author> Authors { get; set; } 
} 


public class Books 
    { 
     public int BookID { get; set; } 
     public string BookName { get; set; } 
     public IEnumerable<Author> Authors { get; set; } 
    } 
public class LibraryDb : DbContext 
{   
    public DbSet<Book> tblBooks { get; set; } 
} 

Answer 1

這應該與作者的列表返回類型書籍的IEnumerable的。

IEnumerable<Books> x = 
      db.tblBooks.Select(t => new Books {BookID = t.BookID, Authors = t.Authors, BookName = t.BookName});