Querying Overriding Entities Using a Self Join and the NHibernate Criteria API - nhibernate

Question

I have a simple Waiver model, and I would like to make a query that returns all the Waivers that are not overridden.
public class Waiver
{
private readonly int id;
protected Waiver()
{
this.id = 0;
}
public virtual int Id { get { return id; } }
public virtual string Name { get; set; }
public virtual string Description { get; set; }
public virtual bool IsRequired { get; set; }
public virtual DateTime EffectiveDate { get; set; }
public virtual Waiver OverriddenWaiver { get; set; }
}
Here's the map:
<class name="Waiver" table="Music_Waivers">
<id name="id" access="field" column="WaiverId" unsaved-value="0">
<generator class="native" />
</id>
<property name="Name" column="Name" />
<property name="Description" column="Description" />
<property name="IsRequired" column="IsRequired" />
<property name="EffectiveDate" column="EffectiveDate" />
<many-to-one name="OverriddenWaiver" class="Waiver" column="OverrideWaiverId" />
</class>
Now I want to have a method in my Repository with the signature public IList GetLatest(). For some reason I'm having a hard time implementing this with the CriteriaAPI. I can write this in T-SQL no problem.

Answer 1

I ended up brute forcing a solution. It's not pretty, but since I know the table will be tiny (probably going to end up being only 5 rows) I came up with the following code solution:
public IList<Waiver> GetLatest()
{
using (var session = SessionManager.OpenSession())
{
var criteria = session.CreateCriteria(typeof (Waiver));
var waivers = criteria.List<Waiver>();
var nonOverridenWaivers = new List<Waiver>();
foreach(var waiver in waivers)
{
bool overrideExists = waivers.Any(w => w.Overrides != null &&
w.Overrides.Id == waiver.Id);
if (!overrideExists)
nonOverridenWaivers.Add(waiver);
}
return nonOverridenWaivers;
}
}