Hibernate在级联全部保存时不生成子id

Question

@Entity
@Table(name = "****")
@Audited
public class Ship
{
    @Id
    @Column(name = "id")
    @GeneratedValue(generator = "uuid")
    @GenericGenerator(name = "uuid", strategy = "uuid")
    private String              id;

    @OneToMany(mappedBy = "associatedShip", cascade = CascadeType.ALL, fetch = FetchType.EAGER)
    private List<ShipLoadlineInformation>   loadlineInformation = new ArrayList<ShipLoadlineInformation>(0);

    .. with other fields constructors, getters and setters.
}

子类：

@Entity
@Table(name = "*********")
@Audited
public class ShipLoadlineInformation
{
    @Id
    @Column(name = "id")
    @GeneratedValue(generator = "uuid")
    @GenericGenerator(name = "uuid", strategy = "uuid")
    private String      id;

    @ManyToOne(fetch = FetchType.EAGER)
    @JoinColumn(name = "ASSOCIATED_SHIP")
    private Ship        associatedShip;

    .. with other fields, constructors, getter and setters
}

我将它保存在我的DAO中，如下所示：

    this.sessionFactory.getCurrentSession().save(ship);

当我试图保存对象ship，它会给我以下错误：

Answer 1

当分离的ShipLoadLineInformation实例包含在Ship.LoadLineInformation集合中时，可能会发生此错误。这样，在保存ship时，save操作级联到它们。

解决这个问题的最简单方法是合并ship（因此也将merge操作级联到loadlineInformation)。

因此，在您的DAO中替换：

this.sessionFactory.getCurrentSession().save(ship)

ship = this.sessionFactory.getCurrentSession().merge(ship)