JPA with JTA: Persist entity and merge cascaded child entities

Question

I have a bidirectional one-to-many relationship with the following entity classes:

0 or 1 client <-> 0 or more product orders

When persis

Answer 1

Hi i had the same problem today, i ask to the openJPA mailing list with this email:

Hi. I have a problem with insert and updating a reference in the same entity.

Im trying to insert a new object (Exam) that has a reference to another object (Person) and at the same time i want to update an attribute (birthDate) of the Person object. The update never happens although i set CascadeType to ALL. The only way this works is doing a persist and after that a merge operation. Is this normal? Do i have to change something??

I dont like the idea of a "manual update" using merge in the Person object because i don't know how many objects (child object of Exam) the user want to update.

Entities:

public class Exam{  
   @ManyToOne(cascade= CascadeType.ALL)
   @JoinColumn(name = "person_id")
   public Person person;
......
}

public class Person{
    private Date birthDate;
   @OneToMany(mappedBy = "person")
    private List exams
.......
}

public class SomeClass{
   public void someMethod(){
      exam = new Exam()
      person.setBirthDate(new Date());
      exam.setPerson(person); 
      someEJB.saveExam(exam);
   }
}

public class someEJB(){

   public void saveExam(Exam exam){
        ejbContext.getUserTransaction().begin();
        em.persist(exam);
        //THIS WORKS
        em.merge(exam.getPerson());
        ejbContext.getUserTransaction().commit();       
   }

}

Do i have to use the MERGE method for every child object?

And the answer was this:

It looks like your problem is that the Exam is new, yet the Person is existing and the existing Entity gets ignored when cascading the persist operation. I believe this is working as expected.

As long as your relationships are set to CascadeType.ALL, you could always change your em.persist(exam); to em.merge(exam);. That would take care of persisting the new exam, and it would also cascade the merge call to the person.

Thanks, Rick

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I hope this can help you.