@ManyToMany delete problem

[Roberto Lopez Lopez]

Hi guys.

I'm dealing with a jpa based app and my basic knowledge doesn't allow me to successfully delete an entity.

I try the following code:

  em = FactoriaDAO.emf.createEntityManager();
  tx = em.getTransaction();
  tx.begin();
  Query q = em.createQuery("delete from SubcategoriaTO sc join sc.usuarios us where us.nick=? and sc.subcategoria=?");
  q.setParameter(1, _clave).setParameter(2, _nick).executeUpdate();
  tx.commit();  

But when I create the query, an exception is thrown:

10:50:44,321 INFO [STDOUT] 2008/09/12 10:50:44 ERROR hibernate.hql.PARSER[http-127.0.0.1-8080-1]: line 1:58: unexpected token: join
java.lang.IllegalArgumentException: node to traverse cannot be null!
at org.hibernate.hql.ast.util.NodeTraverser.traverseDepthFirst(NodeTraverser.java:31)
at org.hibernate.hql.ast.QueryTranslatorImpl.parse(QueryTranslatorImpl.java:254)
at org.hibernate.hql.ast.QueryTranslatorImpl.doCompile(QueryTranslatorImpl.java:157)
at org.hibernate.hql.ast.QueryTranslatorImpl.compile(QueryTranslatorImpl.java:111)
at org.hibernate.engine.query.HQLQueryPlan.<init>(HQLQueryPlan.java:77)
at org.hibernate.engine.query.HQLQueryPlan.<init>(HQLQueryPlan.java:56)
at org.hibernate.engine.query.QueryPlanCache.getHQLQueryPlan(QueryPlanCache.java:72)
at org.hibernate.impl.AbstractSessionImpl.getHQLQueryPlan(AbstractSessionImpl.java:133)
at org.hibernate.impl.AbstractSessionImpl.createQuery(AbstractSessionImpl.java:112)
at org.hibernate.impl.SessionImpl.createQuery(SessionImpl.java:1623)
at org.hibernate.ejb.AbstractEntityManagerImpl.createQuery(AbstractEntityManagerImpl.java:92)
at es.encore.nollego.comun.dao.subcategoria.SubcategoriaDAO_HBM.deleteByNick(SubcategoriaDAO_HBM.java:206)
... 34 more

It seems the problem is the join clause, but I've tried in several ways but didn't succeed. Can anybody help me with this issue?

Here you have the entities:

@Entity
@Table(name="subcategorias")
public class SubcategoriaTO extends TransferObject {
 
  @Id
  private String subcategoria;
  private String categoria;
 
  @ManyToMany(mappedBy = "subcategorias", fetch=FetchType.EAGER)
  Collection<UsuarioTO> usuarios = new HashSet<UsuarioTO>();
 
  public String getSubcategoria() {
    return subcategoria;
  }
  public void setSubcategoria(String subcategoria) {
    this.subcategoria = subcategoria;
  }
  public String getCategoria() {
    return categoria;
  }
  public void setCategoria(String categoria) {
    this.categoria = categoria;
  }
  public Collection<UsuarioTO> getUsuarios() {
    return usuarios;
  }
  public void setUsuarios(Collection<UsuarioTO> usuarios) {
    this.usuarios = usuarios;
  }
 
}

@Entity
@Table(name="usuarios")
public class UsuarioTO extends TransferObject {
 
  @Id
  private String nick;
  private String password;
  private String email;
 
  @ManyToMany(fetch=FetchType.EAGER)
  Collection<SubcategoriaTO> subcategorias = new HashSet<SubcategoriaTO>();
 
  // GETTERS, SETTERS AND CONSTRUCTORS...
}

Previously I've successfully done a select:

  em = FactoriaDAO.emf.createEntityManager();
  Query q = em.createQuery("select sc from SubcategoriaTO sc join sc.usuarios us where us.nick=? and sc.categoria=? order by categoria");
  scs = q.setParameter(1, nick).setParameter(2, catActual).getResultList();

Thanks in advance...

[Roberto Lopez Lopez]

I've changed my code but still no results.

  em = FactoriaDAO.emf.createEntityManager();
  tx = em.getTransaction();
  tx.begin();
  to = select(_clave);
  UsuarioTO uTo = FactoriaDAO.emf.createEntityManager().find(UsuarioTO.class, _nick);
  Query q = em.createQuery("delete from SubcategoriaTO sc where sc.subcategoria=? and sc.usuarios=?");
  q.setParameter(1, _clave).setParameter(2, uTo).executeUpdate();
  tx.commit();

The executeUpdate() method throws the following:

org.hibernate.QueryException: Expected positional parameter count: 2, actual parameters: [
bdd.subcategoria.compras.alimentacion,
es.encore.nollego.comun.to.UsuarioTO[...]
]
[delete from SubcategoriaTO sc where sc.subcategoria=? and sc.usuarios=?]

Where's the problem?

[Ronnie Phelps]

I'm not sure if this helps......

More from the dumbass mistake department. Trying to boot up a Hibernate based project, I was getting this error:

java.lang.IllegalArgumentException: node to traverse cannot be null!

This was occurring during parsing of the named query information in the configuration. Eventually I tracked it down to this query:

@NamedQuery(
name=Comment.COUNT_COMMENTS_BY_ARTICLE,
query="count(*) from Comment where article = :article")

The problem was simply that I'd omitted a vital keyword from the query - because I'm normally retrieving lists of simple entities with queries of the form "from Foo where bar = :spong", which is quite legal, I failed to spot the missing select for ages even where it was staring me in the face! Here's that corrected query:

@NamedQuery(
name=Comment.COUNT_COMMENTS_BY_ARTICLE,
query="select count(*) from Comment where article = :article")

it was taken from....
Node to traverse cannot be null