Question

have a class structure like so
Permit -> Financial ->ICollection instrumentList
Instrument -> Agency

That is, an instance of Permit contains an instance of Financial
An instance of Financial has a collection of Instrument objects
An instance of Instrument has an Agency

Using NHibernate Critieria, I want to get a list of Permits with Instruments of a certain type of Agency
This code, gets all Permits with Financial info (it may be the case the a Permit does not have Financial info, in which case I don’t need it)

// get all all Permits with Financial info
var financialCriteria = DetachedCriteria.For<Financial>()
       .SetProjection(Projections.Property("Permit.Id")); // Permit.Id in Select 

queryCriteria.Add(Subqueries.PropertyIn("Id", financialCriteria)); // Permit.Id in Select

Then I want to restrict that list to Agency of a types 2 & 3:

// then restrict to certain Agency types
var instrumentCriteria = DetachedCriteria.For<Instrument>()
    .SetProjection(Projections.Property("Id")) // Instrument.Id in Select
    .Add(Restrictions.In("Agency", new object[] { 2, 3})); // Where

queryCriteria.Add(Subqueries.PropertyIn("Id", instrumentCriteria)); //

However, when running with the 2nd chunk of code, I get back an empty list when I know there are 2s and 3s.

What I am doing wrong?

Answer 1

If I do understand your scenario correclty, then the instrumentCriteria returns the list of Instrument ID. So with this list we should not limit the queryCriteria but the financialCriteria. So try this:

financialCriteria.Add(Subqueries.PropertyIn("Id", instrumentCriteria)); 

Instead of queryCriteria.Add(Subqueries.PropertyIn(“Id”, instrumentCriteria));

And the result (projection) of the instrumentCriteria should be the owning Financial ID:

var instrumentCriteria = DetachedCriteria.For<Instrument>()
    .SetProjection(Projections.Property("Financial.Id")) // owner ID

EDIT:

In case, that Instrument could reference Financial, or at least has property FinancialId, the syntax returning Permit, filtered by Agency will look like this:

var instrumentCriteria = DetachedCriteria.For<Instrument>()
    // I. Financial as a reference
    .SetProjection(Projections.Property("Financial.ID")) 
    // II. or just a int property FinancialId
    // .SetProjection(Projections.Property("FinancialId")) 
    .Add(Restrictions.In("Agency.ID", new object[] { 2, 3 })); // Where

var financialCriteria = DetachedCriteria.For<Financial>()
    .SetProjection(Projections.Property("ID")) // the ID of instrument
    .Add(Subqueries.PropertyIn("ID", instrumentCriteria));

var queryCriteria = session.CreateCriteria<Permit>()
    .Add(Subqueries.PropertyIn("Financial.ID", financialCriteria));

var result = queryCriteria.List<Permit>();
Assert.IsTrue(result.Any());