Updating a reference to a FK

Question

I've searched for quite a while trying to figure this out. I am using JPA with EclipseLink (Oracle DB). I have a lookup table full of values. I have another table that has a FK relationship to that table. I can insert data fine, but when I try to update the table with a different value, I get an exception. I've tried setting the CASCADE_TYPE but that doesn't have any impact. I thought this would be simple, but maybe I'm missing something.

Lookup table:

public class SomeType implements Serializable {
    @Id
    @Column(name = "ID")
    private Short id;

    @Column(name = "TYPE")
    private String type;

    :
    (getters & setters)
}

Contents:

ID     Type
------------
1     Type1
2     Type2
3     Type3
:       :

Person table (I've left out the Sequencing stuff for brevity):

public class Person implements Serializable {
    @Id
    @Column(name = "ID")
    private Short id;

    @JoinColumn(name = "SOME_TYPE", referencedColumnName = "ID")
    @ManyToOne(optional = false)
    private SomeType someType;

    :
    (getters & setters)
}

Inserting works fine:

EntityManager em;
:
Person p = new Person();
p.setSomeType(new SomeType(1));
em.persist(p);

That results in:

ID      SOME_TYPE
------------------
1         1

But if I want to update Person to change the type:

EntityManager em;
:
Person p = em.find(1);
SomeType newtype = new SomeType(2);
p.setSomeType(newtype);
em.merge(p);

I see the following exception:

Exception [EclipseLink-7251] (Eclipse Persistence Services - 2.5.2.v20140319-9ad6abd): org.eclipse.persistence.exceptions.ValidationException
Exception Description: The attribute [id] of class [SomeType] is mapped to a primary key column in the database. Updates are not allowed.

All I want is the value in the Person table to be updated, like:

UPDATE PERSON set SOME_TYPE = 2 where ID = 1;

Any assistance would be greatly appreciated. Thanks.

Can you add more details about `newtype` you're trying to set? — Barett, May 26 '15 at 15:43
newtype would be something like: SomeType newtype = new SomeType(2); — Larry T, May 26 '15 at 15:46
Since SomeType(1) exists in the database, you should not be creating a new instance to represent that data. Instead, you should be using p.setSomeType(em.find(1, SomeType.class). JPA might be getting confused when it finds an unmanaged instance, making it appear as if you are changing the ID from 1 to 2. Always use and reference the managed instance if possible. — Chris, May 26 '15 at 17:57
@Chris - Excellent! I had not thought about the managed reference angle. That seems to be the fix. Thanks a bunch! — Larry T, May 26 '15 at 18:47

score 0 · Answer 1 · answered May 26 '15 at 19:26

Thanks to Chris for answering this: The update is possible if you use a reference to the managed instance of the object that you want to refer to, not create a new instance.

Person p = em.find(1);
p.setSomeType(em.find(SomeType.class, 2));
em.merge(p);

Updating a reference to a FK

1 Answers1