Could not generate OneToMany records using @ElementCollection in JPA 2

[Jack Bush]

Dear JPA Specialists,

I need your advice on getting a OneToMany (Employee to Photo) relational mapping using @ElementCollection & @CollectionTable in JPA 2.0. Below is a hypothetical code snippet that I am trying to get all the Photo records persisted without success:

@Entity
public class Employee implements Serializable 
{
    @Id @GeneratedValue(strategy=GenerationType.IDENTITY)
    private int id;
    private String firstname;
    private String surname;
    private String address;
    ……

    @ElementCollection(targetClass=Photo.class)
    private Set<Photo> photos = new HashSet<>();
    public Set<Photo> getPhotos() 
    {
	return this.photos;
    }
    
    public void addPhotos(Photo photo) 
    {
        if (!getPhotos().contains(photo)) 
        {
            getPhotos().add(photo);
        }
    }

    public void addPhotos(Set<Photo> photos) 
    {
        for (Photo photo: photos) {
            if (!getPhotos().contains(photo)) 
            {
                getPhotos().add(photo);
            }
        }
    }
}

@Embeddable
public class Photo implements Serializable
{
    public Photo() {}
    public Photo(String name,String description,Date timeTaken) 
    {
        this.name = name;
        this.description = description;
        this.timeTaken = timeTaken;
    }

    private String name;
    private String description;
    @Temporal(TemporalType.DATE)
    private Date timeTaken;
    …..
}

public class EmployeeService 
{
    protected EntityManager em;
    public EmployeeService(EntityManager em) 
    {
        this.em = em;
    }
    
    public Employee createEmployee(String firstname, String surname, String address,….) 
    {
        Employee emp = new Employee();
        emp.setFirstname(firstname);
        emp.setSurname(surname);
        emp.setAddress(address);
        em.persist(emp);        
        return emp;
    }
}

public class recordDailyActivities 
{
    private static EntityManagerFactory emf =
        Persistence.createEntityManagerFactory("JournalPU");
    
    private static EntityManager em = emf.createEntityManager();
    
    public static void main(String[] args) 
    {
         Date today = new Date();
        Employee employee = new Employee();
        set<Photo> todayPhotos = new HashSet<>();

        Photo beforeWorkPhoto = new Photo();
        beforeWorkPhoto.name = "Morning exercise";
        beforeWorkPhoto.description = "Workout at the gym";
        beforeWorkPhoto.timeTaken = today;    

        Photo workPhoto = new Photo();
        workPhoto.name = "At the Office";
        workPhoto.description = "Hard at work";
        workPhoto.timeTaken = today;    

        Photo afterWorkPhoto = new Photo();
        afterWorkPhoto.name = "Catch up with friends";
        afterWorkPhoto.description = "Dinning at the Club";
        afterWorkPhoto.timeTaken = today;    

        todayPhotos.add(beforeWorkPhoto);    
        todayPhotos.add(workPhoto);    
        todayPhotos.add(afterWorkPhoto);    

        employee.addPhotos(todayPhotos);
        EmployeeService service = new EmployeeService(em);

        em.getTransaction().begin();

        Employee managedEmployee = service.createEmployee(employee);
        em.getTransaction().commit();
        em.close();
        emf.close();
    }
}

However, only the last photo (afterWorkPhoto) object has been persisted to the Employee entity instead of all 3 photos. I also want the option of going back to add more new (unique) photos for the same employee in the future.

I am running Eclipselink 2.4.1 (JPA 2.0), Java 7 on Windows XP & 7.

Your advice would be much appreciated.

Thanks in advance,

Jack

[James Sutherland]

In your code you call createEmployee with an Employee but your code takes String, String, ..., so what you posted is not the real code.
Your createEmployee seems to be creating a new Employee, so make sure you are adding the photos to that employee.

Also, your addPhotos method first does a contains, ensure that your equals and hashCode methods are correct.