Nested Includes, how to query?

This was apparently done in 3.x, yet I haven’t found an example of it in the Wiki or any of the issues.

public class Book
{
    [BsonId] public string Id { get; set; }
    public List<Author> Authors { get; set; }
}

public class Author
{
    public string Role { get; set; }
    [BsonRef("users")] public User User { get; set; }
}

public class User 
{
    [BsonId] public string Id { get; set; }
    public string Name { get; set; }
}

I want to query books and get the full User object. How is this possible? I’ve tried:

1. books.Include(x => x.Authors[0].User).FindById(id);
2. books.Include("Authors.User").FindById(id);

Both return only the user’s Id (i.e. no inclusion). Any hints or suggestions would be appreciated.

[mbdavid]

Hi @freezy, there is no nested includes for List. In this case it´s better use Include(Action<T>), so you can define your function, likes:

books.Include(x => x.Authors.ForEach(z => z.User = users.FindById(z.User.UserId))

[ghost]

Hy, I try to achieve the same thing, but I didn’t get it to work. I already tried the example above with the suggested function (but I guess it should be z.User.Id instead of z.User.UserId): books.Include(x => x.Authors.ForEach(z => z.User = users.FindById(z.User.UserId))

But I get the error message (Cannot convert lambda expression to ‘string’ because it’s not a delegate type)

Is this sample still valid with the version 4.1.4.0?