EntityManager EclipseLink problem?

Hello,

I'm somewhat hesitant to post this as I'm not sure this forum is the 
proper place or that I can provide enough information in an appropriate 
manner such as to be of any help but I'm going to give it a shot anyway.


I used the new entity classes from database wizard to create, among 
others, the classes Item and Category. An item has a category and a 
category can have many items and NetBeans has generated a 
itemsCollection in Category.  One of the views on the data is a 
BeanTreeView whose root node contains CategoryBeanNodes whose 
instanceContent contains a category and whose leaf nodes are 
ItemBeanNodes whose instanceContent contains an item.


As I edit the items and save the edits I need to update the view 
accordingly. Now, especially when moving an item from one category to 
another, the first edit/save cycle was fine so I thought all was good 
but then somewhere I moved the item to another category, saved, and then 
back again and saved and then maybe a third edit/save cycle and my view 
was no longer displaying the data properly, either showing the item in  
two categories or not moving the item at all.


Now, I refresh the view after the transaction is committed and the 
entityManager is closed and at that point the database is in the proper 
state and to refresh the view I create a named query to get all the 
categories but the resultList is not what is in the database. Either the 
category's itemCollection doesn't contain the item it should or it 
contains an item that should no longer be there.  I've come up with a 
workaround and ,while it works, it seems pretty ugly to me and I don't 
know why I should need to do it. Basically I'm iterating through the 
resultList and checking if the categories' itemCollections are in the 
state expected and if not correcting them.


But why should this be so?  Maybe this is of use:

public class Item implements Serializable {

...

@JoinColumn(name = "category_id", referencedColumnName = "id")
@ManyToOne
private Category categoryId;

...
}

public class Category implements Serializable {

...

@OneToMany(mappedBy = "categoryId")
private Collection<Item> itemCollection;

...

}


Thanks for taking the time to look,

-- Mark