My class Status is defined as



hbm file is


The LoaderChildCollection should return all statuses whose id is not the entity id fetch. But in result, Status.statuses is null.

What is wrong with my configuration file? Thanks

BTW: I can get non-null result when execute LoaderChildCollection with EntityManager.createNamedQuery

I'm afraid this won't work. You're defining a one-to-many _relationship_ between a parent status object and its children. However, this relationship simply doesn't exist in your database.

You've told hibernate to use the ID field from status to identify the parent object (key column="id"). This is what hibernate does:

1. load the parent object, say status.1
2. run the query to initialize the collection, say status.2 and status.3 returned
3. use the ID field from status.2 to find the parent - returns status.2
4. add child status.2 to collection of parent status.2

Because your query excludes the parent object you'll get an empty list every time.

BTW, I think you're getting a null pointer exception rather than an empty list because you need to include a load-collection element in the sql-query. This is from the docs ch16:

So it is impossible to ask hibernate retrieve status.ToStatuses auomatically with current database tables definitations. We must have two status table, one is fromStatus and the other is toStatus? Thanks

Yes, the statuses can't be loaded as part of the object model without a relationship in place. You don't need 2 status tables, just a parent-child mapping table.

However, if the relationship is as simple as your query suggests (i.e. all statuses except this one), why not just stick to running a HQL query separate from loading the status object?