Question

For example
DB with 2 Tables

Book [BookId (int), Title (nvarchar), ShowInWebshop (bit)] and 
InventoryDetail [InventoryDetailId (int), BookId (int), Quantity (int)]

Execute: SELECT * FROM Books LEFT JOIN InventoryDetails ON books.BookId = InventoryDetails.BookId

The output shows all Book columns and related InventoryDetails columns (including the InventoryDetails.BookId column)
..so far so good …
Trying to transform this query into a Linq one (using LinqPad, comparing several examples, common sense, etc.) I compilated the following generic List (because I wanted a present a list)

private List<Book> Books(int count){
    var books = webshopDB.Books
        .Join<Book, InventoryDetail, int, Book>( webshopDB.InventoryDetails, 
            b => b.BookId, 
            i => i.BookId,
            (b, i) => b )
        .Where(b => b.ShowInWebshop == true)
        .Take(count)
        .ToList();
    return books
}

This module returns a list of books! Not the one I expected, though! It returns only book details such as Title and ShowOnSite NOT the details from the InventoryDetail table: Quantity

What do I forget?

Answer 1

The result how it works so far …

public ActionResult Index()
{                
    // This return a list of tuples {(WebshopDB.Models.Book, WebshopDB.Models.InventoryDetail)}
    // Each tuple containing two items: 
    // > Item1 {WebshopDB.Models.Book}
    // > Item2 {WebshopDB.Models.InventoryDetail}
    var tuple_books = ListOfTuples_BookInventoryDetail(5);
    ...
    // next step(s)
    // add a ViewModel viewmodel
    // ...
    return (viewmodel);
}

private List<Tuple<Book, InventoryDetail>> ListOfTuples_BookInventoryDetail(int count)
{
   var list_of_tuples = new List<Tuple<Book, InventoryDetail>>();

   var showbooks = webshopDB.Books
     .Join(webshopDB.InventoryDetails, b => b.BookId, i => i.BookId, (b, i) => new { b = b, i = i })
     .Where(o => (o.b.ShowInWebshop == true))
     .Where(o => o.b.BookThumbUrl.Contains(".jpg"))
     .OrderByDescending(o => o.b.OrderDetails.Count())
     .Take(count);         

  foreach (var item in showbooks)
  {
    list_of_tuples.Add( Tuple.Create<Book, InventoryDetail>( (item.b), (item.i) ) );
  }
  return list_of_tuples;
}