Hi ,
Is there a seam-way to implement @Entitylisteners ? I've read in the book 'Java Persistence with Hibernate' that the user of EntityManagers is not allowed in callbacks. However; thats the usecase:
I've two Entities which are associated through a @ManyToMany association and i like to implement a last-save-wins-strategy for this set.
@Entity
@Table (name="t_foo")
@EntityListeners(value={Foolistener.class})
public class Foo {
@Id
private Long id;
@Basic
private String name;
@ManyToMany (fetch=FetchType.LAZY)
@JoinTable (name="t_foo_bar",
joinColumns=@JoinColumn(name="foo_id"),
inverseJoinColumns=@JoinColumn(name="bar_id"))
private Set<Bar> bars;
.....
}
@Entity
@Table (name="t_bar")
public class Bar {
@Id
private Long id;
@Basic
private String name;
@ManyToMany (fetch=FetchType.LAZY, mappedBy="bars")
private Set<Foo> foos;
....
}
public class Foolistener {
@PrePersist
public void prePersist (Foo foo) {
// delete the all entries in t_foo_bar which
// reference too foo.getId()
}
@PreUpdate
public void preUpdate (Foo foo) {
// delete the all entries in t_foo_bar which
// reference too foo.getId()
}
}
The first issue on this is, that the callback is only called if the Entity-fields are changed, but not, if the included set changed only. Does anyone know why?
I know i could add a 'changed-set' - flag .. which is not very comfortable if the set is changed directly ;)
I tried to add @Name and @In annotations to the FooListener - but this seams not to work.
I've not much experience with Hibernate-jpa because i worked with jpox-jdo before. If i remember correctly it was no problem to have (restricted) database-access in callback-methods .
Any ideas ?
