Hi there,

I wonder myself, if I really understood the cascade stuff right. Here is what I belive it is all about:

As an example lets assume we have a category category and children productA and productB.

1. Cascade triggers an update of related elements. It can be specified on parent and/or children side. So a product can specify a cascade setting to be applied everytime the product's state changes in a certain way (depending on the kind of the specified cascade setting).

2. Cascade on parent side: Setting cascade='delete' or 'all' would cause productA and productB to be updated if the parent category gets deleted. The update of the products is similar to productA/B.setParent(null).

3. Cascade *-delete-orphan on the parent side would trigger deleting also all assigned children.

4. Cascade on child-side:
- The category is updated if any product it contains gets modified in a certain way. So when a product is removed, the set of related products of the category is updated (the product is removed from within).
- specifying *-delete-orphan on child-side, when productB is deleted, the category is also deleted, causing productA to be updated/deleted (if specified).

5. Here is what I think, what the cascade settings may express:

delete - similar to 'on delete set null' rule of SQL's foreign key mapping
*-delete-orphan - similar to 'on delete cascade' rule of SQL's foreign key mapping

6. The cascade setting 'all' simply means, cascade settings 'save-update' and 'delete' are applied at the same time.

Please tell me if my assumtions are all correct.


Thanks a lot,

Martin (Kersten)

PS: By the way, what is cascade setting save-update for? When do I use it?

No, parent deletion will delete child.


Remove a child from a parent will delete it if it's orphaned.

...

Well seams, I do not understand the cascading right.

So what does save-update means exactly. So if the category has definied save-update on its mapping does this means the set 'null' on cascade?

So if I have a one to many mapping by assoziation (parent is not aware of beeing referenced), how would I do this? You know it needs to be set null if the referenced size gots deleted. I am totally unsure how to handle such thing.

Cascading and association management are not related.
save-update means if parent is saved otr updated, then the cascaded objects (usually children) are saveOrUpdate() too.
For more info on association management is to chech the APrent/Child relationship chapter and http://www.hibernate.org/155.html