Problems with cascading delete with entities

Question

I have a problem with cascading delete. I have two entities, Notebook and Note. One instance of Notebook can have several instances of Note in a Collection< Note >. The two entities are joined with a join table notebook_note that have two columns, the PK from the table of Notebook and Note. Note is not aware of the relation.
From the user interface some elements of the collection<Note> can be added or deleted. I want to delete an element of that collection and make it persisted on the DB.
If I add some Note elements to the collection and then I EntityManager.merge(notebook) (see public void persistNotebook() code below), I have all them persisted on the DB.
However, if I delete some preexisting Note elements, after the merge I found deleted only the corresponding rows from the join table notebook_note BUT the rows in table Note, that was belonging to the deleted instance of Notebook, are NOT removed.
Till now I found a way to do that (see code UserBean below), but I think that there is a simpler and so better way to do that! I hope to receive some suggestions!!
@Entity
public class Notebook implements Serializable {
private static final long serialVersionUID = 1L;
private String userName;
private Collection<Note> notes;
public Notebook() {
public Notebook(String userName) {
this.userName = userName;
notes = new ArrayList<Note>();
@Id
public String getUserName() {
return userName;
public void setUserName(String userName) {
this.userName = userName;
@OneToMany(cascade = {CascadeType.ALL}, fetch = FetchType.EAGER)
public Collection<Note> getNotes() {
return notes;
public void setNotes(Collection<Note> notes) {
this.notes = notes;
@Entity
public class Note implements Serializable {
String note;
public void setNote(String note) {
this.note = note;
public String getNote() {
return note;
@Stateful
public class UserBean implements UserRemote {
private static Logger log = Logger.getLogger(UserRemote.class);
@PersistenceContext(unitName = "etourism-ejbPU")
private EntityManager em;
&hellip;&hellip;
@TransactionAttribute(TransactionAttributeType.REQUIRES_NEW)
public void persistNotebook() {
NotebookDao notebookDao = new notebookDao(em);
notebookDao.merge(notebook);
em.flush();
public void deleteNotebookNote (&hellip;.) {
&hellip;..
//noteFound is the note I want to delete from the Collection<Note>
notebook.getEvents().remove(noteFound);
persistNotebook(); //see method above
*//I have also to explicitally delete the associated note!!!*
*NoteDao noteDao = new NoteDao(em);*
*noteDao.remove(noteDao.read(noteFound.getId()));*
public void addNotebookNote(&hellip;..) {
//add new note to the collection<Note> of the Notebook
Note newNote = new Note(&hellip;);
notebook.getNotes().add(newNote);
persistNotebook();
Where:
public class NotebookDao extends JpaDao<Notebook, String> {
&hellip;&hellip;
public abstract class JpaDao<T, PK extends Serializable> implements IDao<T, PK> {
&hellip;..
public void remove(T entity) {
getEntityManager().remove(entity);
public void merge(T transientObject) {
getEntityManager().merge(transientObject);
}

Answer 1

Thank you gimbal2 for your answer.
You are right saying that a single Note could be bound to multiple notebooks, when using a join table, so the cascade cannot be done automatically by JPA.
However, in my case, a single Note is bound only to one Notebook, so I would like to drop the join table (as you rightly suggest): however when I declare in the Notebook, a relation 1:N in this way ...
@OneToMany(cascade = {CascadeType.ALL}, fetch = FetchType.EAGER)
private Collection<Note> notes;
... the join table is automatically created during the deploy.
Sorry, I am a beginner in EJB3. What kind of relational mapping annotation should I use to have a straight 1:N relationship that doesn't generate a join table?
I think that it should be better to avoid to modify the relationship (es. cascade option) directly in the created db tables and let the logic be declared in the entity code definition: am I right?
Waiting for your suggestion ...
thank you very much
Enzo
Edited by: contini on May 22, 2009 5:37 AM