Is this a bug?
Or am i doing something wrong?
I brought this up in an earlier post to which no-one has responded so i took some time to create a test project. If anyone wants me to zip it up and send, let me know.
The problem: lazy initialisation of the many part of a OneToMany always returns an extra record in the array in the form of a null object at the beginning of the PersistentList.
Variable output
this= PersistenceManagerBean (id=415) id= Integer (id=427) a= ClassA (id=435) classBs= PersistentList (id=467) cachedSize= -1 directlyAccessible= false dirty= false initialized= true initializing= false key= Integer (id=474) list= ArrayList<E> (id=481) elementData= Object[10] (id=499) [0]= null [1]= ClassB (id=501) [2]= ClassB (id=502) [3]= null [4]= null [5]= null [6]= null [7]= null [8]= null [9]= null modCount= 3 size= 3 operationQueue= null owner= ClassA (id=435) role= "test.persistence.ClassA.classBs" session= SessionImpl (id=488) storedSnapshot= ArrayList<E> (id=497) id= Integer (id=474) name= "main " classb= null
Persistence Manager
package test.persistence.manager;
//import java.util.List;
import javax.ejb.Stateless;
import javax.persistence.PersistenceContext;
import org.jboss.annotation.ejb.RemoteBinding;
import test.persistence.ClassA;
import test.persistence.ClassB;
@RemoteBinding(jndiBinding="PersistenceManagerTest")
public @Stateless
class PersistenceManagerBean implements PersistenceManager {
@PersistenceContext(unitName = "ejb3testproject")
javax.persistence.EntityManager em;
public ClassA getClassaById(Integer id) {
ClassA a = new ClassA();
try {
a = (ClassA) em.createQuery(
"SELECT DISTINCT OBJECT(a)" + "FROM ClassA a "
+ "WHERE a.id = :id")
.setParameter("id", id)
.getSingleResult();
}
catch(Exception e)
{
System.out.println(e.getLocalizedMessage());
}
for(ClassB classb:a.getClassBs())
{
System.out.println(classb.getName());
}
return a;
}
}
ClassA Entity
package test.persistence;
import java.io.Serializable;
import java.util.List;
import javax.persistence.*;
import org.hibernate.annotations.IndexColumn;
@Entity
@Table(name="classA")
public class ClassA implements Serializable{
java.lang.String name;
Integer id;
List<ClassB> classBs;
@Id @GeneratedValue(strategy=GenerationType.IDENTITY)
@Column(name="classa_id")
public java.lang.Integer getId() {
return id;
}
public void setId(java.lang.Integer id) {
this.id = id;
}
@Column(name="name")
public java.lang.String getName() {
return name;
}
public void setName(java.lang.String name) {
this.name = name;
}
@OneToMany(mappedBy="classA")
@IndexColumn(name="classb_id")
public List<ClassB> getClassBs() {
return classBs;
}
public void setClassBs(List<ClassB> classBs) {
this.classBs = classBs;
}
}
ClassB Entity
package test.persistence;
import java.io.Serializable;
import java.util.List;
import javax.persistence.*;
@Entity
@Table(name="classB")
public class ClassB implements Serializable{
java.lang.String name;
Integer id;
ClassA classA;
@ManyToOne(fetch=FetchType.EAGER)
@JoinColumn(name="classa_id")
public ClassA getClassA() {
return classA;
}
public void setClassA(ClassA classA) {
this.classA = classA;
}
@Id @GeneratedValue(strategy=GenerationType.IDENTITY)
@Column(name="classb_id")
public java.lang.Integer getId() {
return id;
}
public void setId(java.lang.Integer id) {
this.id = id;
}
@Column(name="name")
public java.lang.String getName() {
return name;
}
public void setName(java.lang.String name) {
this.name = name;
}
}