NHibernate: Persist an object with children - nhibernate

Question

I am trying to persist an object with a collection of child objects. I can't persist the children first as there is a FK relationship. I could save the parent first and then add the children on to it, but this would introduce more work. Basically I'm just trying to save a fully populated object in one step and not break it into parts. Is there something wrong with my mapping (sorry it looks so ugly) or is it my methods?
Parent:
<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2">
<class name="NetworkOrderManagement.Core.Order, NetworkOrderManagement.Core" table="NETORDMGMT.ORDERHEADER" lazy="false" >
<id name="OrderId" column="ORDERID" type="int">
<generator class="seqhilo">
<param name="sequence">ORDERID_SEQ</param>
</generator>
</id>
<property name="TransmissionDate" column="TRANSMISSIONDATE" type="DateTime"/>
<property name="StoreNumber" column="STORENUMBER" type="Int16"/>
<property name="Department" column="DEPARTMENT" type="Int16"/>
<property name="OrderType" column="ORDERTYPE" type="Int16"/>
<property name="OrderSequence" column="ORDERSEQUENCE" type="Int16"/>
<property name="ExtractTime" column="EXTRACTTIME" type="DateTime"/>
<property name="Status" column="STATUS" type="Int16"/>
<property name="ReceivedTime" column="RECEIVEDTIME" type="DateTime"/>
<bag name="OrderDetail" table="NETORDMGMT.ORDERDETAIL"
lazy="false" cascade="all" inverse="true">
<key column="ORDERID" on-delete="cascade"/>
<one-to-many class="NetworkOrderManagement.Core.OrderDetail, NetworkOrderManagement.Core" />
</bag>
</class>
</hibernate-mapping>
Child:
<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2">
<class name="NetworkOrderManagement.Core.OrderDetail, NetworkOrderManagement.Core" table="NETORDMGMT.ORDERDETAIL" lazy="false">
<id name="OrderDetailId" column="ORDERDETAILID" type="int">
<generator class="seqhilo">
<param name="sequence">"ORDERDTLID_SEQ"</param>
</generator>
</id>
<many-to-one name="Order" class="NetworkOrderManagement.Core.Order, NetworkOrderManagement.Core"
column="OrderId" lazy="false" not-null="true" />
<property name="ItemNumber" column="ITEMNUMBER" type="Int32"/>
<property name="OrderQuantity" column="ORDERQUANTITY" type="Int32"/>
<property name="ErrorCode" column="ERRORCODE" type="Int32"/>
</class>
</hibernate-mapping>
Here's my exception:
Test method NetworkOrderManagement.Tests.DataAccess.QuickTests.QuickTest threw exception:
Distribution.Exceptions.DataAccessException: NHibernate Exception --->
NHibernate.PropertyValueException: not-null property references a null or transient valueNetworkOrderManagement.Core.OrderDetail.Order.
I get this when my test below tries to add an orderdetail to the order while it is still transient:
[TestMethod]
public void QuickTest()
{
myOrderRepository = NetworkOrderManagement.Data.RepositoryFactory.Instance.GetOrderRepository();
myOrderDetailRepository = NetworkOrderManagement.Data.RepositoryFactory.Instance.GetOrderDetailRepository();
myOrder = new Order { StoreNumber = RandGen.LittleRand(), Department = RandGen.LittleRand(), TransmissionDate = DateTime.MinValue, ExtractTime = DateTime.MinValue, ReceivedTime = DateTime.MinValue };
myOrder = myOrderRepository.Save(myOrder);
myOrderDetail1 = new OrderDetail {OrderId = myOrder.OrderId, ItemNumber = RandGen.BigRand(), OrderQuantity = RandGen.LittleRand() };
myOrderDetail2 = new OrderDetail {OrderId = myOrder.OrderId, ItemNumber = RandGen.BigRand(), OrderQuantity = RandGen.LittleRand() };
myOrderDetail1 = myOrderDetailRepository.Save(myOrderDetail1);
myOrderDetail2 = myOrderDetailRepository.Save(myOrderDetail2);
myOrder.OrderDetail.Add(myOrderDetail1);
myOrder.OrderDetail.Add(myOrderDetail2);
myOrderRepository.CommitChanges();
myOrderDetailRepository.Delete(myOrderDetail2);
myOrderRepository.CommitChanges();
myOrderRepository.Delete(myOrder);
myOrderRepository.CommitChanges();
}

Answer 1

Specify cascading on the collection, and let NHibernate figure it out for you
http://ayende.com/Blog/archive/2006/12/02/NHibernateCascadesTheDifferentBetweenAllAlldeleteorphansAndSaveupdate.aspx
http://www.hibernate.org/hib_docs/nhibernate/1.2/reference/en/html/example-parentchild.html
Okay, I've seen that you've done that. :)
What you haven't done, is specify the back-reference.
I mean: you add an item to your collection, but this added item has a property to its owner, which you haven't set:
Order o = new Order();
OrderDetail detail = new OrderDetail ();
detail.Order = o;
o.OrderLines.Add (detail);
What would be even better (imho) is this (simplified) :
public class Order
{
private IList<OrderDetail> _details = new List<OrderDetail>();
public ReadOnlyCollection<OrderDetail> Details
{
return new List(_details).AsReadOnly();
}
public void AddOrderLine( OrderDetail d )
{
d.Order = this;
_details.Add (d);
}
public void RemoveOrderLine( OrderDetail d )
{
_details.Remove (d);
}
}