Bidi OneToMany not lazy?

jerger · **Posted:** Thu Nov 02, 2006 11:11 am

Hi.

I try to get a bidi OneToMany loaded lazy ... but the connection is fetched eager all the times, what's the reason?

Used Version is Hbn3.2GA, Annotation3.2GA

Example is:

Code:

@Entity
public class Customer {
  ..
  @OneToMany (mappedBy="customer", cascade = CascadeType.ALL,   fetch=FetchType.LAZY)
  public Set<Film> getFilms() {return films;}
}

@Entity
public class Film {
  ..
  @ManyToOne (fetch=FetchType.LAZY) @JoinColumn (name="FK_CUSTOMER")
  public Customer getCustomer() {
    return customer;
  }
}

Kind regards,
Michael

emmanuel · **Posted:** Tue Nov 07, 2006 6:38 pm

it should work

jerger · **Posted:** Mon Nov 13, 2006 4:00 am

I can provide some example code:
CommitTransaction closes the session also and beginTransaction get's a new one from SessionFactory.getCurrentSession() ... as recommended.

If you look at the produced output, the "from Film" direktion works as expected, but the "from Customer" direction doesn't - Films are loaded eagerly. And no, the toString() method of customer doesn't touch the films set ...

So I've no Idea, what's wrong.

Kind regards,
Michael

Btw -I'm very impressed by the output of the second "System.out.println("Customer ClassName: " + film.getCustomer().getClass().getName() );" in queryDataFromFilm method - good idea and tough work :-)

Code:

 private void insertAndWireData() {
       System.out.println("+++++++++++++++ insertAndWire +++++++++++++++++++");
        
       // insert
       beginTransaction();
       
        Film film1 = new Film(1111, "Der mit dem Wolf tanzt");
        Film film2 = new Film(2222, "Herr der Ringe");
        Film film3 = new Film(3333, "King Kong");
        getSession().save(new Film(4444, "Jagd auf Roter Oktober"));
        customer1 = new Customer("Fritz Frei");
        
        customer1.addFilm(film1);
        customer1.addFilm(film2);
        customer1.addFilm(film3);
        
        getSession().save(customer1);
        getSession().save(new Customer("Bernd Bauer"));
        
        commit();
    }

    private void queryDataFromFilm() {
       System.out.println("+++++++++++++++ queryDataFromFilm +++++++++++++++++++");
       
       beginTransaction();
        List<Film> films = getSession().createQuery("from Film").list();
        for (Film film : films) {
           System.out.println(film);
           if(film.getCustomer() != null) {
              System.out.println("Customer ClassName: " + film.getCustomer().getClass().getName() );
              System.out.println("Customer.id: " + film.getCustomer().getId());
              System.out.println("Customer: " + film.getCustomer());
              System.out.println("Customer ClassName: " + film.getCustomer().getClass().getName() );
           }
            System.out.println();
        }
        commit();
    }
    
    @SuppressWarnings("unchecked")
    private void queryDataFromCustomer() {
       System.out.println("+++++++++++++++ queryDataFromCustomer +++++++++++++++++++");
       
       beginTransaction();
        Customer customer = (Customer) getSession().get(Customer.class, customer1.getId());
        
            System.out.println(customer);            
            System.out.println("Films ClassName: " + customer.getFilms().getClass().getName());
            System.out.println("Films.size: " + customer.getFilms().size());
            System.out.println("Films: " + customer.getFilms());
            System.out.println();
        
        commit();
    }

Code:

Produced output:
+++++++++++++++ queryDataFromFilm +++++++++++++++++++
Hibernate: 
    select
        film0_.id as id0_,
        film0_.FK_CUSTOMER as FK4_0_,
        film0_.inventarNr as inventarNr0_,
        film0_.title as title0_ 
    from
        Film film0_
Film: 4444, Jagd auf Roter Oktober

Film: 3333, King Kong
Customer ClassName: b_MappingErweitert.e_Lazy.model.Customer$$EnhancerByCGLIB$$4693929a
Customer.id: 3
Hibernate: 
    select
        customer0_.id as id1_0_,
        customer0_.name as name1_0_ 
    from
        Customer customer0_ 
    where
        customer0_.id=?
Customer: Customer: 3, Fritz Frei
Customer ClassName: b_MappingErweitert.e_Lazy.model.Customer
...

+++++++++++++++ queryDataFromCustomer +++++++++++++++++++
Hibernate: 
    select
        customer0_.id as id1_0_,
        customer0_.name as name1_0_ 
    from
        Customer customer0_ 
    where
        customer0_.id=?
Hibernate: 
    select
        films0_.FK_CUSTOMER as FK4_1_,
        films0_.id as id1_,
        films0_.id as id0_0_,
        films0_.FK_CUSTOMER as FK4_0_0_,
        films0_.inventarNr as inventarNr0_0_,
        films0_.title as title0_0_ 
    from
        Film films0_ 
    where
        films0_.FK_CUSTOMER=?
Customer: 3, Fritz Frei
Films ClassName: org.hibernate.collection.PersistentSet
Films.size: 3
Films: [Film: 1111, Der mit dem Wolf tanzt, Film: 2222, Herr der Ringe, Film: 3333, King Kong]

emmanuel · **Posted:** Mon Nov 13, 2006 6:42 pm

getFilms().size() does

jerger · **Posted:** Tue Nov 14, 2006 3:10 am

Hi Emmanuel,

you're right, but I expect the output from

Code:

            System.out.println(customer);            
            System.out.println("Films ClassName: " + customer.getFilms().getClass().getName()); 

definitely before the "select ... from film ..." !
So the question is, why the second db-access is executed before the content of the PersistentSet is accessed the first time.

Kind regards,
Michael

emmanuel · **Posted:** Tue Nov 14, 2006 11:28 am

Either, customer.toString() does something or the output is unordered.
Try assertTrue( Hibernate.isInitialized( customer.getFilms() ); before any System.out

jerger · **Posted:** Tue Nov 14, 2006 6:29 pm

Hi Emmanuel,

you mad my day :) I found the error in customer.setFilms ... sorry for not posting the complete customer code ...
I will switch to field access and the special setter will be okay, I think :-)

Thx and kind regards,
Michael

Code:

@OneToMany (mappedBy="customer", cascade = CascadeType.ALL, fetch=FetchType.LAZY)
public Set<Film> getFilms() {return films;}
public void setFilms(Set<Film> films) {
       // reset old backrefs
       for (Film film : this.films) {
          film.setCustomer(null);         
      }
       // set new backref
       for (Film film : films) {
         film.setCustomer(this);
      }
       // remember the given films
       this.films = films;
    }