[hibernate-issues] [Hibernate-JIRA] Created: (HHH-6776) Hibernate inserts duplicates into @OneToMany collection
Hibernate inserts duplicates into @OneToMany collection
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Key: HHH-6776
URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-6776
Project: Hibernate Core
Issue Type: Bug
Affects Versions: 4.0.0.CR4, 3.6.7
Environment: MySQL 5.1.54
Reporter: Damien
Priority: Minor
Attachments: Test.zip
Consider following entities (getters and setters are omitted for brevity):
{code:java}
@Entity
public class Parent
{
@Id
@GeneratedValue
private int id;
@OneToMany(mappedBy="parent")
private List<Child> children = new LinkedList<Child>();
}
@Entity
public class Child
{
@Id
@GeneratedValue
private int id;
@ManyToOne
private Parent parent;
}
{code}
Now consider following code snippet, which persists one parent and one child entity and
then prints the children of the parent.
{code:java}
// persist parent entity in a transaction
EntityManager em = emf.createEntityManager();
em.getTransaction().begin();
Parent parent = new Parent();
em.persist(parent);
int id = parent.getId();
em.getTransaction().commit();
em.close();
// relate and persist child entity in a new transaction
em = emf.createEntityManager();
em.getTransaction().begin();
parent = em.find(Parent.class, id);
// *: parent.getChildren().size();
Child child = new Child();
child.setParent(parent);
parent.getChildren().add(child);
em.persist(child);
System.out.println(parent.getChildren()); // -> [Child@36bf7916, Child@36bf7916]
em.getTransaction().commit();
em.close();
{code}
The child entity is wrongly being inserted twice into the list of children of the parent
entity.
When doing one of the following, the code works fine (no duplicate entries in the list):
- remove the mappedBy attribute in the parent entity
- perform some read operation on the list of children (e.g. uncomment line marked by *)
Also, when testing against another persistence provider, the code works as expected (no
duplicates).
Take a look at axtavt's
[answer|http://stackoverflow.com/questions/7903800/hibernate-inserts-dupli...]
to my post on Stack Overflow. He seems to know why this problem occurrs.
I have attached a simple JUnit test for this issue.
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