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);     } }