Question

Trying to Project a EF linq result into IEnumerable of interfaces, something simialr to below but can’t get it working, any hints is apreciated:

                IEnumerable<IBook> books = (from b in context.Library
                                                  (select new (Book() as IBook)
                                                  {
                                                      Id = b.Id,
                                                      Title = b.Title
                                                  }).AsEnumerable<IBook>;

Error : Cannot convert Lambda expression to type string because it is not delegate type.

PS : It is explicit interface implementation so I can’t just use the following that works with implicit interface implementation:

                IEnumerable<IBooks> books = (from b in context.Library
                                                  select new Book()
                                                  {
                                                      Id = b.Id,
                                                      Title = b.Title
                                                  }).AsEnumerable<IBook>();

Answer 1

Try this:

IEnumerable<IBooks> books = (from b in context.Library
    select new Book
    {
        Id = b.Id,
        Title = b.Title
    }).Cast<IBook>();

Or you can do this:

IEnumerable<IBooks> books = (from b in context.Library
    select new Book
    {
        Id = b.Id,
        Title = b.Title
    } as IBook);

Third option (for your explicit interface):

IEnumerable<IBook> books = context.Library.Select(b =>
{
    IBook book = new Book();  //as IBook - Might need a cast here 
    book.Id = b.Id;
    book.Title = b.Title;
    return book;
};