JPA 2.1 Foreign Key isn't saving on ManyToOne cascade

Question

I have two classes.

public class Reservation {
    @OneToMany(cascade = CascadeType.ALL, orphanRemoval=true, mappedBy = "reservation")
    private List<Night> nights;  \\assume getters and setters
}

public class Night {
    @ManyToOne
    @JoinColumn(name = "RESERVATION_ID")
    private Reservation reservation;
}

My save works like this:

Reservation r = new Reservation();
r.getNights().add(new Night()); 
return dao.save(r);

This works, as in it saves the Reservation, and it saves the Night. But when I look at the database, the column RESERVATION_ID in the NIGHT table is null.

In previous projects (before upgrading to Java 8 and JPA 2.1), I didn't need to manually set the parent object on the child in order for that association to save. Did something change, or am I doing something wrong?

Edit:

This saves the association correctly, but it didn't used to be necessary.

Reservation r = new Reservation();
Night n = new Night();
n.setReservation(r);
r.getNights().add(n);
return dao.save(r);

Thank you for your link, however I don't see how it helps answer my question. It is a bidirectional relationship, as I show in the code. — Risu, Jul 22 '14 at 21:11
it was back to your question `Did something change, or am I doing something wrong?` So the answer is, you are not missing. That's the way it should be implemented. However you can make it unidirectional and add/remove them separately. That's your choice (AFAIK). — pms, Jul 22 '14 at 21:34
Forgive my confusion, but are you saying `r.getNights().add(new Night());` (before the edit) should work to save the association? — Risu, Jul 22 '14 at 21:45
Sorry my bad. Yes you need to set the parent object in the child. You can do it in the Parent class (child's getter method). — pms, Jul 22 '14 at 21:49
Alright, so after the edit is how it's supposed to be, and before the edit was just some auto-magic that I shouldn't have been relying on. Correct? — Risu, Jul 22 '14 at 21:51
right. Was that working in your previous project? Because AFAIK it shouldn't work properly. — pms, Jul 22 '14 at 21:59
Thank you for your help. Did you want to write up an answer that I can accept so you can get points? — Risu, Jul 22 '14 at 22:01

score 1 · Accepted Answer · answered Jul 22 '14 at 22:05

1

According to JPA example provided in link below, you need to set the parent object in the child. You can do it in the Parent class (child's getter method)

http://en.wikibooks.org/wiki/Java_Persistence/OneToMany

answered Jul 22 '14 at 22:05

pms

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JPA 2.1 Foreign Key isn't saving on ManyToOne cascade

1 Answers1