NHibernate Projection to DTO - web-services

Question

I am unfamiliar with NHibernate projection. I am attempting to use it so I can return a List<> rather that an IList<>. I am not having much luck with projecting to the DTO as of yet. I have the following query and Domain objects. So to begin I am just trying to get a list of Orders given an EmployeeID. I am looping through the resulting list and adding it to a List because I wish to be able to serialize this list. Can anyone tell me how far off I am with the Projection? I have searched and found some examples that are not similar to my own. Basically.. I just want to create a List of of the DTOs.
Thanks!
public List<EmployeeOrder> GetEmployessOrdersDTO(int empid)
{
var emporders = new List<EmployeeOrder>();
ICriteria criteriaSelect = NHibernateSessionManager.Instance.GetSession().CreateCriteria(typeof (Orders))
.CreateCriteria("Employees")
.Add(Expression.Eq("EmployeeID", empid));
criteriaSelect.SetProjection(
Projections.ProjectionList()
.Add(Projections.Property("Products"), "OrderedProducts"));
criteriaSelect.SetResultTransformer(NHibernate.Transform.Transformers.AliasToBean(typeof(EmployeeOrder)));
criteriaSelect.List<EmployeeOrder>();
foreach (var order in emporders)
{
emporders.Add(order);
}
return emporders;
}
Orders:
public class Orders
{
public virtual int OrderID { get; private set;}
public virtual string CustomerID { get; set; }
public virtual DateTime OrderDate { get; set; }
public virtual DateTime RequiredDate { get; set; }
public virtual DateTime ShippedDate { get; set; }
public virtual Employees Employee { get; set; }
public virtual IList<Products> Products { get; private set; }
}
Employees:
public class Employees
{
public virtual int EmployeeID { get; private set;}
public virtual string LastName { get; set;}
public virtual string FirstName { get; set;}
public virtual string City { get; set; }
public virtual DateTime HireDate { get; set; }
public virtual string Title { get; set; }
public virtual IList<Orders> Orders { get; private set; }
}
EmployeeOrderDTO:
public class EmployeeOrder
{
public virtual string EmployeeName { get; set; }
public virtual string EmployeeTitle { get; set; }
public virtual DateTime RequiredDate { get; set; }
public virtual List<Products> OrderedProducts { get; set; }
}

Answer 1

In nHibernate 2.1, the .List() method actually already returns a List type, so you can just cast:
var list = (List<EmployeeOrder>)criteriaSelect.List<EmployeeOrder>();
However, if you want to be future safe and not depend on assumptions based on the implementation of the current nHibernate, I'd write an extension method accepting ICriteria:
public static List<T> ToList<T>(this ICriteria criteria)
{
return criteria.List<T>().ToList();
}

Answer 2

Change
criteriaSelect.List<EmployeeOrder>();
to
List<EmployeeOrder> employeeOrders = criteriaSelect.List<EmployeeOrder>() as List<EmployeeOrder>;