Get the child id after merging the parent in hibernate

Question

Is there any clean way to get the id of a child object, when the parent has been merged?

I.e.

Parent parent = parentDao.get(parentid);
Child child = new Child();
parent.addChild(child);
parentDao.merge(parent);
child.getId() // is null

I have a many to one relationship between the parent and the child.

Another question asked this, and the only solution that worked was to traverse the list of children, but that sounds horrible and hacky.

Surely there must be a nicer solution to this.

Eventually changed my model so that I could just persist the child entity. — wybourn, Jul 15 '16 at 11:51

score 0 · Accepted Answer · answered Jul 14 '16 at 17:00

Considering the following bi-directional entity structure, i.e.

class Parent{
    @OneToMany
    List<Child> children;
}

class Child{
    @ManyToOne
    Parent parent;
}

You'll need to persist the child first in order to get the id for the child.

like entityManager.persist(child) and then associate it with the parent unless you have set cascadeType to Cascade.ALL in Parent class.

1 Answers1