I have a "User " model class, a "Role" model class, and a "Gene" model class which are maped to a user table, a role table, a user-role table and gene table

There are four roles (ROLE_ADMIN, ROLE_RESEARCHER and ROLE_COLLABORATOR and ROLE_PUBLIC.

A user may have multi-roles

User {
// private ......
private Set<Role> roles = new HashSet<Role>();
....



@ManyToMany(targetEntity = Role.class, fetch = FetchType.EAGER)
@JoinTable(name = "user_role",
joinColumns = { @JoinColumn(name = "user_id") },
inverseJoinColumns = { @JoinColumn(name = "role_id") })
public Set<Role> getRoles() {
return roles;
}

public void setRoles(Set<Role> roles) {
this.roles = roles;
}

......
}

Gene implements Serializable {
..........
private User

@ManyToOne(fetch=FetchType.EAGER)
@JoinColumn(name="user_id", nullable=false)
@org.hibernate.annotations.ForeignKey(name="FK_GENE_FROM_USER")
public User getUser() {
return user;
}

public void setUser(User user) {
this.user = user;
}


A generic Dao, hibernateDao, generic manager and managerImpl implementation were used. fetch in User and Gene class are set to FetchType.EAGER.

There are two users in User table. user A with id=1 has four roles , user B with id=2 has only one role (ROLE_RESEARCHER).
In the Gene table, there are 339 records all with user_id=1,

The geneManager.getAll(); it show 1356 records, which is 4x339 records. However, if just smiply set user_id=2 in the Gene table, the function will get the right 339 records.

or keep the user_id=1 and just simply set the FetchType to FETCHTYPE.LAZY in the Gene Class, the function will get the right 339 records.


Any one can give some suggestion? Is this a bug in Hibernate?

To this problem, a DistinctRootEntityResultTransformer is needed

what is the code in geneManager.getAll()?

If you have used the "GenericDao" in the books of "Java Persistence and with Hibernate". you can find in the GenericDaoHibernate. The code is as following:

/**
* {@inheritDoc}
*/
@SuppressWarnings("unchecked")
public List<T> getAll() {

// return super.getHibernateTemplate().loadAll(this.persistentClass);
List<T> list =super.getHibernateTemplate().loadAll(this.persistentClass);
return list;
}

I have change the code as following:

/**
* {@inheritDoc}
*/
@SuppressWarnings("unchecked")
public List<T> getAll() {

// return super.getHibernateTemplate().loadAll(this.persistentClass);
List<T> list =super.getHibernateTemplate().loadAll(this.persistentClass);
DistinctRootEntityResultTransformer transformer = new DistinctRootEntityResultTransformer();
list = transformer.transformList(list);
return list;
}