Question

I have:

@Entity
public class EmailAndName {
...
}

and

@Entity
public class MessageDetails {
    @ManyToMany(fetch = FetchType.LAZY, cascade = CascadeType.ALL)
    @JoinTable(name = "MessageDetails_to")
    public Set<EmailAndName> getTo() {
        return to;
    }
}

when I

public static void main(String []a)
{
    StatelessSession sess = HibernateUtils.getSessionFactory().openStatelessSession();
    sess.beginTransaction();
    MessageDetails messageDetails = new MessageDetails();
    messageDetails.setTo(new HashSet<EmailAndName>());
    EmailAndName emailAndName = (EmailAndName) sess.get(EmailAndName.class, 1L);
    if (emailAndName == null ) throw new RuntimeException();
    messageDetails.getTo().add(emailAndName);
    sess.insert(messageDetails);
    sess.getTransaction().commit();
}

MessageDetails_to table is not populated. What should I do? I don’t want to write native queries. Thank you.

Answer 1

You havent read through hibernate-doc for stateless session

It clearly states that:

Operations performed using a stateless session never cascade to associated instances. Collections are ignored by a stateless session.

And you are trying to add a Set<EmailAndName>. A stateless session is a lower-level abstraction, much closer to the underlying JDBC. SO if you really want make your code work and populate MessageDetails_to.. You need to go for Session. You will need to define the equals and hashCode methods for your POJO’s 🙂

so your modified code will be:

public static void main(String []a)
{
   try{
    Session sess = HibernateUtils.getSessionFactory().openSession();
    sess.beginTransaction();
    MessageDetails messageDetails = new MessageDetails();
    messageDetails.setTo(new HashSet<EmailAndName>());
    EmailAndName emailAndName = (EmailAndName) sess.get(EmailAndName.class, 1L);
    if (emailAndName == null ) throw new RuntimeException();
    messageDetails.getTo().add(emailAndName);
    sess.save(messageDetails);
    sess.getTransaction().commit();
 }
catch(HibernateException e)
 {
   sess.getTransaction.rollback();
   e.printStackTrace();
 }
  finally{
       sess.close();
  }

You must always have a try catch enclosed, so that you can identify the exceptions(if any) and make it work 🙂