Hi All, I've got a patent-child (Customer being the parent and Address being the child) setup in NHibernate setup with a one-to-many relationship. I have all-delete-orphan cascade and all works well except.

1. When I load a customer (with Addresses)
2. Add an address, modify an address and remove and address

If I do step 1 and 2 within the same session:
- My customer is updated (even if no properties on it are modified, but I guess the change to teh Addresses collection triggers this)
- The new address is inserted into the db
- The removed address is deleted from the db

Which is PERFECT...my problem occurs when I do step 1 and 2 in two different sessions, in that case, all the above happens in addition to:
- All unmodified addresses are also updated

This is a big problem for me as I plan to have lots of objects on my customer and I need updates to be generated only when necessary.

My entity configuration is as follows:

=======================
Customer.hbm.xml
=======================
<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" assembly="DomainProject" namespace="DomainProject.Domain">
<class name="Customer">
<id name="Id">
<generator class="identity" />
</id>
<version name="Version" access="backfield"/>
<property name="Name" />
<property name="Category" />
<property name="Active" />
<property name="CreatedBy" />
<property name="UpdatedBy" />
<property name="CreatedDate" />
<property name="UpdatedDate" />

<bag name="Addresses" lazy="false" inverse="true" cascade="all-delete-orphan">
<key column="CustomerId"/>
<one-to-many class="Address"/>
</bag>
</class>
</hibernate-mapping>

=======================
Address.hbm.xml
=======================
<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" assembly="DomainProject" namespace="DomainProject.Domain">
<class name="Address">
<id name="Id">
<generator class="identity" />
</id>
<version name="Version" access="backfield"/>
<property name="CustomerId" />
<property name="Street" />
<property name="Suburb" />
<property name="City" />
<property name="Active" />
<property name="CreatedBy" />
<property name="UpdatedBy" />
<property name="CreatedDate" />
<property name="UpdatedDate" />
</class>
</hibernate-mapping>

The thing that puzzled me is that NHibernate figures out the changes to my Address collection and it does delete orphaned records, I spend a lot of time debugging through and I can see it's caching them in "AbstractEntityPersister" what I can't figure our is why It's only making the linkage for collections and not for entities as well. Surely this info can be relinked!

Otherwise...

I've tried re-selecting the customer and used both Merge and Lock commands to set the session up correctly but got the following errors:

Calling Merge throws or Lock throw:
a different object with the same identifier value was already associated with the session: 8, of entity: DomainProject.Domain.Customer

public void Update(Customer customer)
{
Customer old = GetById(customer.Id);

using (ISession session = NHibernateHelper.OpenSession())
using (ITransaction transaction = session.BeginTransaction())
{
//session.Merge(old);
//session.Lock(old, LockMode.None);

session.SaveOrUpdate(customer);
transaction.Commit();
}
}
public Customer GetById(int customerId)
{
using (ISession session = NHibernateHelper.OpenSession())
return session.Get<Customer>(customerId);
}

Thanks a lot for your help.