Problem saving new object with set of new objects

rwwilden · **Joined:** Tue May 31, 2005 8:57 am **Posts:** 10

Hibernate version: 3.1 beta1 (Annotations 3.1 beta4)

I have a very simple problem and am quite sure I'm doing something wrong here. I have the following case (leaving out some unnecessary code):

Code:

@Entity
class A {
   @OneToMany(mappedBy="a", cascade = {CascadeType.ALL})
   public Set<B> getBs() {...};
}

@Entity
class B {
   @ManyToOne(optional=false, fetch=FetchType.EAGER)
   public A getA() {...};
}

In other words, a bi-directional one-to-many relation that cascades all operations.

Now I attempt to do the following:

Code:

A a = new A();
a.addB(new B());
session.save(a);

All very simple. But this fails. Due to the CascadeType.ALL, an attempt is made to save the B object related to A. However, since there is no A yet, if B is saved, the foreign key constraint on A can not be satisfied. This constraint exists because of the optional=false attribute on the getA() method.

So for saving this, I first need to save the B object, then add it to A and then save A.

Is it impossible to do it the way I want, or am I missing something?

rwwilden · **Joined:** Tue May 31, 2005 8:57 am **Posts:** 10

rwwilden wrote:

So for saving this, I first need to save the B object, then add it to A and then save A.

Small correction: for saving this, I need to create an A object, save it, add the new B object and save A again.

EstebanLM · **Posted:** Fri Sep 23, 2005 12:54 pm

Maybe this can help you.
I had the same problem, and I just perform the save inside a transaction, as follows:

Code:

A a = new A();
a.addB(new B());

Transaction tx = session.beginTransaction();
session.save(a);
tx.commit();

This works, though I don't know why... :p

athu9999 · **Joined:** Mon Mar 28, 2005 12:58 pm **Posts:** 27

Maybe you're not supplying the Join column between A and B:

Code:

@Entity
class B { 
    @ManyToOne
    @JoinColumn(name = "XXX")
    public A getA() { ...};
}

emmanuel · **Posted:** Fri Sep 30, 2005 4:11 am

you have to do b.setA(a); mappedBy is equivalent to inverse=true