EF Eager fetching derived class

Question

I´m using EF6 and trying to eager fetch the whole structure of an object. The problem is that i´m using inheritance.

Let´s say that i have this classes.

Answer 1

Shortly, it's not possible out of the box.

The only workaround I can suggest is to materialize the master query result, then execute several OfType queries with the necessary Includes using the same filter as the master query, and rely on EF navigation property fixup.

It requires an inverse navigation property in the Base class:

public abstract class Base
{
   // ...
   public A A { get; set; }
}

Then you can use something like this:

public IEnumerable GetAll(string id)
{
    var a = _ctx.A.Where(x => x.Id == id).ToList();
    _ctx.Base.OfType().Include(e => e.SomeClass).Where(e => e.A.Id == id).Load();
    _ctx.Base.OfType().Include(e => e.SomeOtherClass).Where(e => e.A.Id == id).Load();
    return a;
}

The same idea can be used w/o inverse navigation property but with using the returned base Ids as filter:

public IEnumerable GetAll(string id)
{
    var a = _ctx.A.Include(e => e.Bases)
        .Where(x => x.Id == id).ToList();

    var baseIds = a.SelectMany(e => e.Bases.OfType().Select(b => b.Id));
    db.Base.OfType().Include(e => e.SomeClass)
        .Where(e => baseIds.Contains(e.Id)).Load();

    baseIds = a.SelectMany(e => e.Bases.OfType().Select(b => b.Id));
    db.Base.OfType().Include(e => e.SomeOtherClass)
        .Where(e => baseIds.Contains(e.Id)).Load();

    return a;
}