Question

I am using nhibernate and I wrote a linq query and it is not returning what I expect.

public ParentA()
{
    public virtual Id {get; set;}
    public virtual Name {get; set;}
    public virtual IList<ChildA> ChidrenA {get; set;}

   public ParentA()
   {
       ChidrenA = new List<ChildA>();      
   }
}

public ChildA()
{
    public virtual Id {get; set;}
    public virtual Name {get; set;}
    public virtual IList<ChildB> ChidrenB {get; set;}
    public virtual ParentA ParenteA {get; set;}
   public ChildA()
   {
       ChidrenB = new List<ChildB>();      
   }
}

public ChildB()
{
    public virtual Id {get; set;}
    public virtual Name {get; set;}
    public virtual ChildA {get; set;}
}

The above code is my domains. The fluent nhibernate would be very basic and nothing special going on so I have not included it.

The query I have is

base.unitOfWork.Session.Query<ParentA>()
  .Where(x => x.Id == parentAId)
  .FetchMany(x => x.ChildrenA)
  .ThenFetchMany(x => x.ChildrenB)
  .FirstOrDefault();

What I expected to happen

It will find 1 or 0 parent records. If it does find that one record it will eager load all ChildrenA and then all ChildrenB.

What is happening

It finds 1 or 0 parent records. It then only takes 1 or 0 record for ChildrenA and ChildrenB.

Why is only taking the first found record for ChildrenA and ChildrenB?

If I change FirstToDefault() to .toList() I get everything I expect but I find it pointless as there should only be one record with that parent record.

Answer 1

Try moving .FirstOrDefault to directly after the .Where clause:

.Where(x => x.Id == parentAId).FirstOrDefault()...