Jpa - remove in M-M relationship

Question

Hello,
I have these tables
USUARIO (1) - (M) USUARIO_SUBGRUPO (M) - SUBGRUPO
Entities:
Usuario.class
@OneToMany(cascade = CascadeType.ALL, mappedBy = "usuario")
private java.util.Collection <UsuarioSubgrupo> usuarioSubgrupoCollection;
UsuarioSubgrupo.class
@JoinColumn(name = "CD_USUAR", referencedColumnName = "CD_USUAR")
@ManyToOne
private Usuario usuario;
@JoinColumn(name = "CD_SUBGR", referencedColumnName = "CD_SUBGR")
@ManyToOne
private Subgrupo subgrupo;
Subgrupo
@OneToMany(cascade = CascadeType.ALL, mappedBy = "subgrupo")
private java.util.Collection <UsuarioSubgrupo> usuarioSubgrupoCollection;
I am trying to remove an User (Usuario) that has some datas in USUARIO_SUBGRUPO table like this:
em.getTransaction().begin();
// usuario is Managed
usuario = em.find(Usuario.class, id);
for (UsuarioSubgrupo us: usuario.getUsuarioSubgrupoCollection()) {
em.remove(em.merge(us));
us.setUsuario(null);
us.setSubgrupo(null);
usuario.setUsuarioSubgrupoCollection (null);
em.remove(em.merge(usuario));
em.getTransaction().commit();
And I am getting an error saying this cannot be done because Usuario has datas in UsuarioSubgrupo.
Could someone help me?
Thanks!

Answer 1

Hi,
I am sorry, the problem wasn't in the code but in database. I had some garbage in the USUARIO_SUBGRUPO table that make me get lost. Now it's working.
And about calling the merge, yes you're right, I saw that after send the post :)
Now my code is:
em.getTransaction().begin();
// usuario is Managed
usuario = em.find(Usuario.class, id);
usuario.getUsuarioSubgrupoCollection().
remove(usuario.getUsuarioSubgrupoCollection);
em.remove(usuario);
em.getTransaction().commit();
Thanks a lot.