Question

I have this entities:

public class A 
{
    public List<B> B { get;set; }
}

public class B 
{
    public DateTime Date { get; set; }
    public List<C> C { get; set; }
}

public class C { }

and I need to get C from A where B.Date > DateTime.Now..
I’m trying something like this:

var users = _db.A
.Select(a => new
{
    A = a,
    B = a.B
    .Where(b => b.Date >= DateTime.Now).Select(p => new
    {
        B = b,
        C = b.C
    })
})
.AsEnumerable()
.Select(a => a.A)
.ToList();

but C is always null.
How can I get C?

---

UPDATE

If I set virtual in ‘List C’ it works!!
How can I make this work without setting virtual?

Answer 1

You can try to build the object graph manually. The following will run only a single database query (when the first foreach loop executes, the rest is performed in memory):

var userQuery = _db.A
    .Select(a => new
    {
        A = a,
        B = a.B.Where(b => b.Date >= DateTime.Now).Select(p => new
        {
            B = b,
            C = b.C
        })
    });

var users = new List<A>();
foreach (var u in userQuery)
{
    A a = u.A;
    a.B = new List<B>();
    foreach (var x in u.B)
    {
        B b = x.B;
        b.C = x.C;
        a.B.Add(b);
    }
    users.Add(a);
}