Hibernate - Problems with @onetomany

[everson santos]

Hi! I think my mapping doesn't work, because when I did the query the fields from child table didn't load, my list getRoles came empty.

user table:
id login password activated
1 xx xx 1

role table:
id nome id_user
1 ROLE_ADMIN 1
2 ROLE_USER 1


User.java:

@Transient
   private List<Role> roles = new ArrayList<Role>();

@OneToMany(cascade=CascadeType.ALL, mappedBy="user")
public List<Role> getRoles() {
return roles;
}

Role.java:

@Transient
private User user;

@ManyToOne
@JoinColumn(name="id_user")
public User getUser() {
	return user;
}

My select from hibernate:

 select
        user0_.id as id1_,
        user0_.activated as activated1_,
        user0_.login as login1_,
        user0_.password as password1_ 
    from
        user user0_ 
    where
        user0_.login=?

My find method:

public User findUserLogin(String user) {
return  (User) getHibernateTemplate().find("from User u where u.login = ? ",user).get(0) ; 
}

I got this approach from:
http://docs.jboss.org/hibernate/stable/annotations/reference/en/html_single/#entity-mapping-association

2.2.5.3.2.1. Bidirectional
Since many to one are (almost) always the owner side of a bidirectional relationship in the EJB3 spec, the one to many association is annotated by @OneToMany( mappedBy=... )

@Entity
public class Troop {
@OneToMany(mappedBy="troop")
public Set<Soldier> getSoldiers() {
...
}

@Entity
public class Soldier {
@ManyToOne
@JoinColumn(name="troop_fk")
public Troop getTroop() {
...
}

[Cameron Wallace McKenzie]

The get(0) confuses me a bit?

Are you getting the User to return, without the associated objects? I'm wondering what SQL gets generated in the logs.

If all else fails, just hardcode a value for the loginName and make sure that's not the weak link. Here's an example from my website of a little HQL that hardcodes a value but does return a result:

Session session = HibernateUtil.beginTransaction();
String hql="from User where loginName = 'mj' ";
Query query = session.createQuery(hql);
Object o  = query.uniqueResult();
User u = (User)o;
System.out.println(u.getLoginName());
System.out.println("\n\n");
HibernateUtil.commitTransaction();     

It's a very simple approach that uses Annotations and a simple session.createQuery(hql) approach.

Tutorial on HQL and Hibernate with JPA Annotations

Any exception being thrown?

-Cameron McKenzie

[Rahul Babbar]

everson santos wrote:
User.java:

@Transient
   private List<Role> roles = new ArrayList<Role>();

@OneToMany(cascade=CascadeType.ALL, mappedBy="user")
public List<Role> getRoles() {
return roles;
}

Role.java:

@Transient
private User user;

@ManyToOne
@JoinColumn(name="id_user")
public User getUser() {
	return user;
}

Why is the "roles" in User and "user" in Role marked as transient?

[everson santos]

Rahul Babbar wrote:

everson santos wrote:
User.java:

@Transient
   private List<Role> roles = new ArrayList<Role>();

@OneToMany(cascade=CascadeType.ALL, mappedBy="user")
public List<Role> getRoles() {
return roles;
}

Role.java:

@Transient
private User user;

@ManyToOne
@JoinColumn(name="id_user")
public User getUser() {
	return user;
}

Why is the "roles" in User and "user" in Role marked as transient?

I did @transient because I don't have theses atributes in my tables(user and role). I think is correct isn't ?

[Rahul Babbar]

everson santos wrote:
I did @transient because I don't have theses atributes in my tables(user and role). I think is correct isn't ?

I admit, i am not very sure...
Your "Roles" did not load because you have not set the "lazy" attribute to false....The default for One to many (from User to roles) is true.

As a result, when you load the User, your roles are not loaded.

You will need to set the "lazy" attribute to "false".

[everson santos]

Cameron Wallace McKenzie wrote:The get(0) confuses me a bit?

Are you getting the User to return, without the associated objects? I'm wondering what SQL gets generated in the logs.

If all else fails, just hardcode a value for the loginName and make sure that's not the weak link. Here's an example from my website of a little HQL that hardcodes a value but does return a result:

Session session = HibernateUtil.beginTransaction();
String hql="from User where loginName = 'mj' ";
Query query = session.createQuery(hql);
Object o  = query.uniqueResult();
User u = (User)o;
System.out.println(u.getLoginName());
System.out.println("\n\n");
HibernateUtil.commitTransaction();     

It's a very simple approach that uses Annotations and a simple session.createQuery(hql) approach.

Tutorial on HQL and Hibernate with JPA Annotations

Any exception being thrown?

-Cameron McKenzie

I got the return here:

public UserDetails loadUserByUsername(String username) throws UsernameNotFoundException, DataAccessException {

		try {   				
            User user = securityDao.findUserLogin(username);//seu metodo que faz uma consulta por login e retorna um objeto User   
            return user;   
        } catch (Exception e) {   
        	e.printStackTrace();
}}

SecureDao.java

@Transactional(readOnly=false, propagation=Propagation.REQUIRED)
	User findUserLogin(String user);

Any exception being thrown?

nothing


I'll go check your suggest...

thanks

[everson santos]

Rahul Babbar wrote:

everson santos wrote:
I did @transient because I don't have theses atributes in my tables(user and role). I think is correct isn't ?

I admit, i am not very sure...
Your "Roles" did not load because you have not set the "lazy" attribute to false....The default for One to many (from User to roles) is true.

As a result, when you load the User, your roles are not loaded.

You will need to set the "lazy" attribute to "false".

You were sure.

I erased @transient and marked fetch=FetchType.EAGER.

Working fine now.

[Cameron Wallace McKenzie]

Awesome! Thanks for the update.

-Cameron McKenzie

[Jowel Poquiz]

I have also stumbled on this problem.In addition, here is the explanation on why removing the @Transient is necessary. Inverse Fields vs Persistent Fields here