I have a ManyToMany relationship. If I attempt to merge a detached instance of the owning side of that relationship the changes to the ManyToMany fail to be persisted. The merge propertly takes place and the persistence context is correctly updated but the SQL commands to update the database are not sent when the session is flushed. I'm using HA 3.2.0 and EM 3.2.0. If I replace the core 3.2.1 jar with 3.2.0 the operation works perfectly. If I attempt the operation on an attached instance the operation works perfectly. it only doesn't work with 3.2.1 with a detached instance. Here are the example entities and example code to duplicate the problem.

--------------Animal.java---------------
@Entity
@Cache(usage = CacheConcurrencyStrategy.TRANSACTIONAL)
@SuppressWarnings("serial")
public class Animal implements Serializable {

   @Id @GeneratedValue
   private Long id;
    private String name;
    @ManyToOne
    @Basic(fetch=FetchType.LAZY)
    private Classification classification;
    @ManyToMany
    @JoinTable(name="ANIMAL_COUNTRY",
          joinColumns=@JoinColumn(name="ANIMAL_ID"),
          inverseJoinColumns=@JoinColumn(name="COUNTRY_ID"))
    @Cache(usage = CacheConcurrencyStrategy.TRANSACTIONAL)
    @Basic(fetch=FetchType.LAZY)
    private List<Country> countries;
    @SuppressWarnings("unused")
   @Version
    private Long version;
    
    /** SNIP Getters and Setters **/

}

------------Country.java-----------------
@Entity
@Cache(usage = CacheConcurrencyStrategy.READ_ONLY)
@SuppressWarnings("serial")
public class Country implements Serializable {

   @Id @GeneratedValue @Column(updatable=false)
   private Long id; //NOPMD - wheelermm
   @Column(unique=true, nullable=false)
    public String name;
    @Basic(fetch=FetchType.LAZY)
    @ManyToMany(mappedBy="countries")
    @Cache(usage=CacheConcurrencyStrategy.TRANSACTIONAL)
    public List<Animal> animals;
}


-----------Example code to duplicate problem----------------
//Start Transaction
Animal animal = entityManager.find(Animal.class, 21l);
animal = (Animal)SerializationUtils.clone(animal); // Detach the animal
List<Country> countries = new ArrayList<Country>();
countries.add(countryService.findAllCountries().get(2));
animal.setCountries(countries);
animal.setClassification(entityManager.find(Classification.class, 1l);
animal.setName("Modified Animal");
entityManager.merge(animal);
//Commit Transaction


When the example code above runs both the animal.name and animal.classification are persisted but the change of country is not persisted. the object returned from entityManger.merge() contains the correct country but the db is never updated. if I comment out the clone() (making it not detached) everything works fine. If I downgrade to 3.2.0 everything works fine.

Mike

Forum post: http://forum.hibernate.org/viewtopic.php?t=968226