Entity Framework eager loading in many nested entities - entity-framework

Question

I have six classes as shown below -
Class A{
int ValA;
ICollection<B> AllBs;
}
Class B{
int ValB;
ICollection<C> AllCs;
}
Class C{
int ValC;
ICollection<D> AllDs;
}
Class D{
int ValD;
ICollection<E> AllEs;
}
Class E{
int ValE;
ICollection<F> AllFs;
}
Class F{
int ValF;
}
I have to eager load an A entity with specific id and I want the result must load all the nested collections eagerly.
I wrote the following code to achieve the same -
var entity = _context.A.Where(a => a.Id == 1)
.Include(a => a.AllBs
.Select(b => b.AllCs
.Select(c => c.AllDs
.Select(d => d.AllEs
.Select(e => e.AllFs)))))
.FirstOrDefault();
Have I written the include statements correctly ? All the nested collections are not getting loaded properly. They are getting loaded upto AllBs, AllCs and further collections are not loaded.
Kindly help.

Answer 1

If this is EF Core you will want to use
_context.A
.Include(a => a.AllBs)
.ThenInclude(b => b.AllCs)
.ThenInclude(c => c.AllDs)
.ThenInclude(d => d.AllEs)
.ThenInclude(e => e.AllFs)
.Single(a => a.Id == 1)
Intellisense may give you a bit of grief diving through collections but it does work through.
For EF6, your statement should work, so if not I would look specifically at your mappings to ensure your FKs are resolving correctly. I'd also remove the .Where() & .FirstOrDefault() and instead use a .Single() at the end. It should not matter in the query generation, but Include statements are best placed before any filtering. Use an SQL Profiler to capture the SQL being sent to the server to see what tables are being requested and how they are joining. This might highlight some FK resolution errors.