Question

nHibernate allows you to sort column names easily, so long as the column name matches the mapping. So, for example:

 Map(Function(x) x.CreatedOn)


 criteria = criteria.AddOrder(New Global.NHibernate.Criterion.Order("CreatedOn", True))

Is all above board and cosy.

However I’m having trouble getting the right syntax to order by properties which are inferred from the object rather than directly mapped. I’m not even sure if the latter is possible. Consider the following:

 HasMany(Function(x) x.Shipments).Cascade.SaveUpdate()

Public Overridable ReadOnly Property Items() As IList(Of OrderItem)
    Get
        Return Shipments.SelectMany(Function(x) x.Items).ToList().AsReadOnly()
    End Get
End Property

How would one order by Items.Count in that situation? Trying the objvious:

criteria = criteria.AddOrder(New Global.NHibernate.Criterion.Order("Items.Count", True))

Leads to an error of “could not resolve property: Items”

Cheers,
Matt

Answer 1

To order by part of a component, you would specify the property name and then the component part, just ask if you were accessing it off the object in code.

criteria = criteria.AddOrder(New Global.NHibernate.Criterion.Order("Name.Surname", True))

As for your second question, this is not easily accomplished with Criteria, but can easily be written using HQL:

query = session.CreateQuery("select s from Shipment s order by size(s.Items)")