Hibernate一對一級聯-全部不起作用

'各位高手，目前正在學習Spring Hibernate。我添加了 HibernateUtil 類以在創建/洗掉等命令后使用它。我使用 cascadeALL 進行一對一映射，當我運行洗掉或創建類時，它們只更新資料庫中的 Instructor 表，而不是相關的 Instuctor Detail 表。它可以作業，如果我在 CreateDemo 類中撰寫命令 - session.save(tempInstructor); session.save(tempInstructorDetail); 但據我所知，我應該只能寫 session.save(tempInstructor); - 這也會更新鏈接表。DeleteDemo 也是如此。為什么 cascade = CascadeType.ALL 不起作用？

enter code here
      

@Entity
@Table(name = "instructor")
public class Instructor {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column( name = "id")
private int id;

@Column(name = "first_name")
private String firstName;

@Column(name = "last_name")
private String lastName;

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

@OneToOne(cascade = CascadeType.ALL)
@JoinColumn(name = "instructor_detail_id")
private InstructorDetail instructorDetail;
enter code here





@Entity
@Table(name = "instructor_detail")
public class InstructorDetail {

@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name = "id")
private int id;

@Column(name = "youtube_channel")
private String youtubeChannel;

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

enter code here



@SpringBootApplication
public class CreateDemo {

public static void main(String[] args) {
    SpringApplication.run(CreateDemo.class, args);

   Instructor tempInstructor = new Instructor('Vilma', 'Kalna', '[email protected]');
   InstructorDetail tempInstructorDetail = new InstructorDetail('www.vilma- 
teaching.com/youtube', 'teaching');

    try (Session session = HibernateUtil.getSessionFactory().openSession()) {

        session.beginTransaction();
        System.out.println('Saving instructor: '   tempInstructor);
        //this will also save the details object
        //because of CascadeType.ALL
        session.save(tempInstructor);
        session.save(tempInstructorDetail);
        session.getTransaction().commit();

    } catch (Exception e) {
        e.printStackTrace();
    }
 }
}

enter code here



public class DeleteDemo {
public static void main(String[] args) {

    try (Session session = HibernateUtil.getSessionFactory().openSession()) {

        session.beginTransaction();

        int theId = 2;
        Instructor tempInstructor = session.get(Instructor.class, theId);

        System.out.println('Found instructor: '   tempInstructor);

        if(tempInstructor != null){
            System.out.println('Deleting: '   tempInstructor);
            //will also delete associated details obj (Cascade)
            session.delete(tempInstructor);
        }

        session.getTransaction().commit();

    } catch (Exception e) {
        e.printStackTrace();
enter code here

public class HibernateUtil {
private static SessionFactory sessionFactory;

public static SessionFactory getSessionFactory() {

    if (sessionFactory == null) {
        try {
            Configuration configuration = new Configuration();

            // Hibernate settings equivalent to hibernate.cfg.xml's properties

            Properties settings = new Properties();
            settings.put(Environment.DRIVER, '');
            settings.put(Environment.URL, '');
            settings.put(Environment.USER, '');
            settings.put(Environment.PASS, '');
            settings.put(Environment.DIALECT, 'org.hibernate.dialect.MySQL5Dialect');
            settings.put(Environment.SHOW_SQL, 'true');
            settings.put(Environment.CURRENT_SESSION_CONTEXT_CLASS, 'thread');

            configuration.setProperties(settings);

            configuration.addAnnotatedClass(Instructor.class);
            configuration.addAnnotatedClass(InstructorDetail.class);

            ServiceRegistry serviceRegistry = new StandardServiceRegistryBuilder()
                    .applySettings(configuration.getProperties()).build();

            sessionFactory = configuration.buildSessionFactory(serviceRegistry);

        } catch (Exception e) {
            e.printStackTrace();
        }

    }
    return sessionFactory;
enter code here

uj5u.com熱心網友回復：

InstructorDetail 類也需要進行級聯，因為它應該是雙向的。

@OneToOne(cascade = CascadeType.ALL)
@JoinColumn(name = "instructor_id")
private Instructor instructor;

并為講師創建 setter 和 getter。我希望這會奏效

uj5u.com熱心網友回復：

在創建物體時應該有雙向映射。在講師詳細資訊中創建以下屬性并為其創建 getter 和 setter。

    @OneToOne(cascade = CascadeType.ALL)
    @JoinColumn(name = "instructor_id")
    private Instructor instructor;
    

在講師詳細資訊物體中創建以下函式

public void add(Instructor instructor) {
       this.instructor = instructor;
       instructor.setInstructorDetail(this)
    }

在創建講師時，使用與講師物件相關的講師詳細資訊物件呼叫上述函式，例如，

instructorDetail.add(instructor);

標籤：

上一篇：創建一個可分頁查詢，其中每個物體的子項不超過N個

下一篇：從具有不同型別主鍵的多個表中獲取記錄。休眠