Linq Contains and Distinct

I have the following 3 tables with their fields

Books(Id_Book | Title | Year)

Book_Themes (Id | Id_Book| Id_Theme)

Themes (Id_Theme| Title)

I also have an Giud array with Id_Themes

Guid [] themesArray = new Guid []{new Guid("6236c491-b4ae-4a2f-819e-06a38bf2cf41"), new Guid("06586887-7e3f-4f0a-bb17-40c86bfa76ce")};

I'm trying to get all Books containing any of the Theme_Ids from the themesArray

This is what I have so far which is not working. Not sure how to use Contains in this scnenario.

int index = 1; int size= 1开发者_StackOverflow社区0;
var books = (from book in DB.Books
               join bookWThemes in DB.Book_Themes
               on book.Id_Book equals bookWThemes.Id_Book

               where themesArray.Contains(bookWThemes.Id_Theme)                           
               orderby book.Year
               select book)
               .Skip((index - 1) * page)
               .Take(size);

I'm getting an error on themesArray.Contains(bookWThemes.Id_Theme): System.Guid[] does not contain a definition for Contains. Also I'm not sure where to put the Distinct

****UPDATE****

noticed that my Model had Id_Theme as nullable... I changed the DB and didn't reflect the changes on my model. So to answer the question if it's nullable just change the Contains line to themesArray.Contains(bookWThemes.Id_Theme.Value)... and with this change it works.

Thanks for all the help!.

It's strange that your LINQ query is breaking down on .Contains. All three of the forms IEnumerable<> and List<> work for me.

    [Test]
    public void Test43()
    {
        var a = new List<Guid>(){new Guid(),new Guid(),new Guid()};
        a.Contains(new Guid());  // works okay
        var b = (IEnumerable<Guid>)a;
        b.Contains<Guid>(new Guid()); // works okay
        b.Contains(new Guid()); // works okay 
    }

For the "distinct" question, put the call here:

           select book)
           .Distinct()  // <--
           .Skip((index - 1) * page)

Try casting the Guid[] to List<Guid> and then you can use Contains on it.

where themesArray.ToList().Contains(bookWThemes.Id_Theme)