休眠：CascadeType.PERSIST 不起作用，但 CascadeType.ALL 用于保存对象

Question

@Entity
@Table(name = "Section_INST")
public class Section {

@javax.persistence.Id
@GeneratedValue(strategy = GenerationType.SEQUENCE,generator = "Section_ID_GENERATOR")
@SequenceGenerator(name = "Section_ID_GENERATOR",sequenceName = "Section_ID_SEQUENCER" , initialValue = 1 , allocationSize = 1)
@Column(name = "Section_ID")
private int Id;

@Column(name = "Section_Name")
private String name;

@OneToOne(optional = false,cascade = CascadeType.PERSIST)
@JoinColumn(name = "Exch_ID")
private Exchange exchange;

//---Constructor and Getter Setters-----
}


@Entity
@Table(name = "EXCHANGE_INST")
public class Exchange {

@Id
@GeneratedValue(strategy = GenerationType.SEQUENCE,generator = "Exchange_ID_GENERATOR")
@SequenceGenerator(name = "Exchange_ID_GENERATOR",sequenceName = "Exchange_ID_SEQUENCER" , initialValue = 1 , allocationSize = 1)
@Column(name = "Exchange_ID")
private int Id;

@Column(name = "Exchange_name")
private String name;

@OneToOne(mappedBy ="exchange")
private Section section;

//-----------Getter and Setter...And Constructor

}

以下程序不起作用->

    final SessionFactory sessionFactory = configuration.buildSessionFactory();
    final Session session = sessionFactory.openSession();
    session.beginTransaction();

    final Exchange exchange = new Exchange("MyExchange");
    final Section section = new Section("MySection" , exchange);
    exchange.setSection(section);
    session.save(section);

    session.getTransaction().commit();
    session.close();

如果我将 Section.java 中的级联选项更改为 CascadeType.ALL，那么它可以工作。

@OneToOne(optional = false,cascade = CascadeType.PERSIST)   --- > CascadeType.ALL 
@JoinColumn(name = "Exch_ID")
private Exchange exchange;

我认为 PERSIST 应该保存我的对象 d=，但它会引发异常：

org.hibernate.TransientPropertyValueException：非空属性引用瞬态值 - 瞬态实例必须在当前操作之前保存：Section.exchange -> Exchange

Answer 1

对于要级联的save() 操作，您需要启用CascadeType.SAVE_UPDATE，使用专有的Hibernate Cascade 注释，因为save() 不是标准的JPA 操作。或者您需要使用persist() 方法，而不是save() 方法。