openjpa, update, error 'PK has non-default value'

Question

I wonder if anyone has come across this error and can explain what's happening:

<openjpa-2.1.1-SNAPSHOT-r422266:1087028 nonfatal user error>
org.apache.openjpa.persistence.InvalidStateException: 
Primary key field com.qbe.config.bean.QBEPropertyHistory.id of com.qbe.config.bean.QBEPropertyHistory@1c710ab has non-default value. 
The instance life cycle is in PNewProvisionalState state and hence an 
existing non-default value for the identity field is not permitted. 
You either need to remove the @GeneratedValue annotation or modify the 
code to remove the initializer processing.

I have two objects, Property and PropertyHistory. Property has OneToMany List of PropertyHistory:

@OneToMany(fetch = FetchType.LAZY, cascade=CascadeType.MERGE, orphanRemoval=false)
@JoinColumn(name="PROPERTY_NAME")
@OrderBy("updatedTime DESC")
private List<QBEPropertyHistory> history = new ArrayList<QBEPropertyHistory>();

And Property object is loaded and saved like this:

public T find(Object id) {
    T t = null;
    synchronized(this) {
        EntityManager em = getEm();
        t = em.find(type, id);
        //em.close(); //If this is uncommented, fetch=LAZY doesn't work. And fetch=EAGER is too slow.
    }
    return t;
}

public T update(T t) {
    synchronized(this) {
        EntityManager em = getEm();
        em.getTransaction().begin();
        t = em.merge(t);
        em.getTransaction().commit();
        em.close();
        return t;
    }
}

In the service layer I load a property using find(id) method, instantiate a new PropertyHistory, add it into property prop.getHistory().add(propHist) then call update(prop) and get the above error.

The error disappears if I close EntityManager in find() but that breaks lazy loading and prop.getHistory() always returns null. If I set fetch=EAGER it becomes unacceptably slow as there are 10s of 1000s of records and I need to select thousands of property objects at a time and history is not needed 99.99% of the time.

I can't remove the @GeneratedValue as the error text suggests because it is generated (DB2, autoincrement). Now I wonder how would i "modify the code to remove the initializer processing" ?

Thanks!

Answer 1

The problem is that you are trying to share an Entity across persistence contexts(EntityManager). You could change your methods to take an EntityManager instance and use the same EM for the find and update operations.