Question

I have Customer, CustomerGroups, Groups tables. Customer has 1:n with CustomerGroups and Groups has 1:n with CustomerGroups. In the create customer screen, user can choose the groups information of existing customer. So when I create a new customer, I am retrieving groups from existing customer and adding them

///
Customer cust = new Customer();
foreach(var item in getothercustomergroups())
cust.groups.add(item);
commit

This code is generating update statement and updating the customergroups table with newly added customerid, instead of inserting new records with new customerid. Due to this, all groups with prev. customer are gone. Could anyone please explain this behavior.

Answer 1

From your description, I would guess getcustomergroups has gotten customergroups from an existing customer via NHibernate. If so, NHibernate has associated each item in the foreach loop with the existing customer, so when you add item to a new customer, the new customer assumes ownership of that item.

You can avoid this by cloning the item. See How do I copy an object with NHibernate