Updating entities in Extended Persistence Context - jpa

Question

I have a form - Workflow where there are fields like wfName, assignedUser, dueDate, turnAroundTime. etc.
It is backed by an entity Workflow with a reference to the User entity as Many-to-One.
When a change is made to the assignedUser field( it is an email address) and the form is submitted, I get a Unique-constraint violation error on the USER entity.
I am not trying to achieve this. I only want to replace the User in the Workflow entity.
The save function is performed by a Stateful session bean, with an EXTENDED persistence context.
Am I missing something here? Is this the correct way to updated information in a referenced field?
While setting the updated User I am doing
User user = workflow.getUser();
//This user has its email address changed on the screen so getting a fresh reference of the new user from the database.
user = entitManager.createQuer("from User where email_address=:email_address").setParameter("email_address", user.getEmailAddress).getSingleResult();
//This new found user is then put back into the Workflow entity.
workflow.setUser(user);
entityManager.merge(workflow);
No exception is thrown at the time these lines are executed, but later in the logs I find that it threw a
Caused by: java.sql.SQLException: ORA-00001: unique constraint (PROJ.UK_USER_ID) violated
There is no cascading configuration present in the entities.
The following is the association code for the entities-
The workflow-User relation
#ManyToOne(fetch = FetchType.LAZY)
#JoinColumn(name = "USER_ID", nullable = false)
#NotNull
public GwpsUser getUser() {
return user;
}
public void setUserByUserId(User user) {
this.user = user;
}
The User-Workflow Relation
#OneToMany(fetch = FetchType.LAZY, mappedBy = "User")
public Set<Workflow> getWorkflowsForUserId() {
return workflowsForUserId;
}
public void setWorkflowsForUserId(
final Set<Workflow> WorkflowsForUserId) {
this.workflowsForUserId = workflowsForUserId;
}
In the SFSB I have two methods loadWorkflow() and saveWorkflow().
#Begin(join = true)
#Transactional
public boolean loadProofData(){
//Loading the DataModel here and the conversation starts
}
If I add flushMode = FlushModeType.MANUAL inside #Begin. The saveWorkflow() method saves the data properly, only for the first time. I have to go somewhere else and then come back to this page if I want to make any further changes.
The saveWorkflow() method looks like
#SuppressWarnings("unchecked")
public boolean saveWorkflow() throws FileTransferException {
//Do some other validations
for (Workflow currentWorkflow : workflowData) {
User user = currentWorkflow.getUser();
//This user has its email address changed on the screen so getting a fresh reference of the new user from the database.
user = entitManager.createQuery("from User where email_address=:email_address").setParameter("email_address", user.getEmailAddress).getSingleResult();
//This new found user is then put back into the Workflow entity.
currentWorkflow.setUser(user);
}
//Do some other things
}
Not using the merge() method here, but still the problem persists.

Answer 1

Why are you calling merge? Is the workflow detached (serialized)?
If it is not detched, you should not call merge, just change the object and it should be updated.
You should have a setUser method, not setUserByUserId? Not sure how this is working, perhaps include your full code. Your get/set method might be corrupting your objects, in general it is safer to annotate fields instead of method to avoid code in your get/set method to cause odd side-effects.
Ensure you are not creating two copies of the object, it seems your merge is somehow doing this. Enable logging and include the SQL. Calling flush() directly after your merge will cause any errors to be raise immediately.