AddOrder on nHibernate with non fieldname columns

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 开发者_运维问答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

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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)")