Hibernate: Problem with cascade delete for one to many relation - sql

Question

I have following entity model.
#Entity
#Table(name="product")
public class ProductEntity {
#Id
#GeneratedValue(generator = "uuid2")
#GenericGenerator(name = "uuid2", strategy = "uuid2")
private UUID id;
...
#OneToMany(mappedBy = "productEntity", cascade = CascadeType.ALL)
private List<ProductAddonEntity> productAddonEntities;
}
#Entity
#Table(name="product_addon")
public class ProductAddonEntity {
#Id
#GeneratedValue(generator = "uuid2")
#GenericGenerator(name = "uuid2", strategy = "uuid2")
private UUID id;
...
#ManyToOne()
#JoinColumn(name = "addon_id")
private ProductEntity addonEntity;
}
I want to delete product, and that deletion should also delete all ProductAddon entities, connected with this product. So I declare one to many relation with all cascade types.
But when I try to delete some product, at the beginning Hibernate tries to set null addon_id in product_addon table. But this column have non-null constraint, so deletion fails.
So I added to annotation #ManyToOne parameters
#JoinColumn(name = "addon_id", nullable = false, updatable = false)
But now hibernate just tries to delete product, before deleting product_addon entities, connected with this product. And this deletion fails because of foreign key constraint (Cannot delete or update a parent row: a foreign key constraint fails).
What can be a problem here? This application also uses liquibase, so foreign keys generated not by hibernate. For example, foreign key for addon_id doesn't have actions on delete, but I'm thinking that hibernate does not need these actions, because it works on higher data layer

Answer 1

Orphan removal is aggressive remove cascading mode to remove child object whenever the parent object needs to be deleted(#OneToOne and #OneToMany relationships).
This feature added from JPA 2.0 version.JPA deletion operation
The difference between the two settings is in the response to disconnecting a relationship. For example, such as when setting the address field to null or to another Address object.
#Entity
class Employee {
#OneToOne(cascade=CascadeType.REMOVE)
private Address address;
}
If only cascade=CascadeType.REMOVE is specified no automatic action is taken since disconnecting a relationship is not a remove operation.
#Entity
class Employee {
#OneToOne(orphanRemoval=true)
private Address address;
}
If orphanRemoval=true is specified the disconnected Address instance is automatically removed. This is useful for cleaning up dependent objects (e.g. Address) that should not exist without a reference from an owner object (e.g. Employee).