Hello,
I'm a little bit confused about a left join fetch behaviour.
In this test case, i try to fetch my 3 children using a left join fetch.
But my collection is null after closing the em.
It was expected to be fetched before closing the em, no ?
In fact, that is the objective of the fetch purpose (i guess ?).
import java.util.HashSet; import java.util.Set; import javax.persistence.CascadeType; import javax.persistence.Entity; import javax.persistence.EntityManager; import javax.persistence.EntityManagerFactory; import javax.persistence.Id; import javax.persistence.ManyToMany; import javax.persistence.Persistence; import javax.persistence.TypedQuery; public class ObjectDbTest { public static void main(String[] args) { EntityManagerFactory emf = Persistence.createEntityManagerFactory( "objectdb:$objectdb/db/test.tmp;drop"); EntityManager em = null ; // Merge parent1 em = emf.createEntityManager(); if (! em.getTransaction().isActive()) { em.getTransaction().begin(); } MyEntity e1 = new MyEntity("parent1"); e1.addChild(String.valueOf("child1")); e1.addChild(String.valueOf("child2")); e1.addChild(String.valueOf("child3")); em.merge(e1); // Ok, seems to be well merged em.getTransaction().commit(); em.clear(); em.close(); // Try to retrieve parent and children using left join fetch em = emf.createEntityManager(); TypedQuery<MyEntity> query = em.createQuery("SELECT DISTINCT m FROM MyEntity m JOIN FETCH m.entityChildren", MyEntity.class); MyEntity myEntity = query.getSingleResult(); // Ok my em is now closed, let's check if children are retrieved em.close(); emf.close(); if (myEntity.getEntityChildren() == null) { System.out.println("Children not fetched !"); // We fall in this case, it is excepted ? } else { System.out.println("Number of children = " + myEntity.getEntityChildren().size()); } } @Entity public static class MyEntity { @Id private String name; public String getName() { return name; } public void setName(String name) { this.name = name; } // Also tested with List private Set <MyEntityChild> entityChildren = new HashSet <MyEntityChild> (); MyEntity(String name) { this.name = name; } public void addChild(String name) { entityChildren.add(new MyEntityChild(name)); } @ManyToMany(targetEntity = MyEntityChild.class, cascade = CascadeType.ALL) public Set<MyEntityChild> getEntityChildren() { return this.entityChildren; } public void setEntityChildren(Set <MyEntityChild> entityChildren) { this.entityChildren = entityChildren ; } } @Entity public static class MyEntityChild { @Id private String name; MyEntityChild(String name) { this.name = name; } } }
Regards,
Xirt
