I have a Provider object which has child Facility objects:

/**
* @hibernate.set role="facilities" lazy="true" cascade="delete"
* @hibernate.collection-key column="provider_id"
* @hibernate.collection-one-to-many class="com.webify.hta.domain.Facility"
*/
public Set getFacilities() {
return facilities;
}

Notice the cascade delete setting. I'm getting an error when I try to delete a Provider object:

"Cannot add or update a child row: a foreign key constraint fails"

Now the SQL right before that is this statement:

Hibernate: update hta_facility set provider_id=null where provider_id=?

Now why is Hibernate trying to do this? Shouldn't it be deleting the Facility objects and then deleting the top-level Provider object (i.e. delete the leaf nodes of the object tree first). Why is Hibernate performing updates in the first place? provider_id is marked as not null so this statement will fail.

I'm using mysql 4.0.18.

http://www.hibernate.org/hib_docs/refer ... d-cascades

all-delete-orphan

This one keeps burning me. I have found that (on case a case by case basis) I can solve this one in the following ways:

Sometimes inverse="true" on the parent collection solves it, but this doesn't help if I am managing the children via the parent collection.

Sometimes cascade="all-delete-orphan" on the parent collection solves it, when i [b]am[/b/ managing the children via the parent collections.

Sometimes I simply need a many-to-one reference in the child mapping (and object) that points back to the parent.

With these three bits of info I have been able to overcome all of my mapping mistakes.

this is much easier and well documented

it only depends one how you have configured transitive persistence (attribute cascade).

If your association is bidirectionnal, this is another thing: you must manage your instances--> read hibernate in action, forum, wiki, reference guide about addChild, removeChild methods ...