ManyToMany持久化

Question

我有一个NOTIFICATION表，它包含一个ManyToMany关联：

@Entity
@Table(name="NOTIFICATION")
@NamedQuery(name="Notification.findAll", query="SELECT f FROM Notification f")
public class Notification {

/** SOME COLUMN DEFINITION NOT IMPORTANT FOR MY CASE
    COD, DATE, ID_THEME, ID_TYP, IC_ARCH, ID_CLIENT, INFOS, NAME, TITRE_NOT, ID_NOT
**/

        @ManyToMany
        @JoinTable(
            name="PJ_PAR_NOTIF"
            , joinColumns={
                @JoinColumn(name="ID_NOTIF")
                }
            , inverseJoinColumns={
                @JoinColumn(name="ID_PJ_GEN")
                }
            )
        private List<PiecesJointesGen> piecesJointesGens;
}

因此，我有一个名为PJ_PAR_NOTIF的关联表。

我试图持久化一个Notification实体。下面是来自值对象的piecesJointesGens初始化：

@PersistenceContext(unitName="pu/middle")

private EntityManager entityMgr;

FoaNotification lFoaNotification = new FoaNotification();

for(PieceJointeGenVO lPJGenVO : pNotificationVO.getPiecesJointes()){
        PiecesJointesGen lPiecesJointesGen = new PiecesJointesGen();
        lPiecesJointesGen.setLienPjGen(lPJGenVO.getLienPieceJointeGen());
        lPiecesJointesGen.setIdPjGen(lPJGenVO.getIdPieceJointeGen());
        lNotification.getFoaPiecesJointesGens().add(lFoaPiecesJointesGen);
}

entityMgr.persist(pNotification);

坚持是行不通的。JPA为Notification生成第一个insert，这是可以的：

insert 
into
    NOTIFICATION
    (COD, DATE, ID_THEME, ID_TYP, IC_ARCH, ID_CLIENT, INFOS, NAME, TITRE_NOT, ID_NOT) 
values
    (?, ?, ?, ?, ?, ?, ?, ?, ?, ?)

然后，JPA尝试在我的关联表中插入值，但是piecesJointesGen暂时不存在：

insert 
into
    PJ_PAR_NOTIF
    (ID_NOTIF, ID_PJ_GEN) 
values
    (?, ?)

所以，我有一个错误：

GRAVE: EJB Exception: : java.lang.IllegalStateException: org.hibernate.TransientObjectException: object references an unsaved transient instance - save the transient instance before flushing: com.entities.PiecesJointesGen

有办法让JPA在piecesJointesGen插入之前插入PJ_PAR_NOTIF吗？

Answer 1

将piecesJointesGens映射修改为@ManyToMany(cascade = CascadeType.PERSIST)。