org.hibernate.id.IdentifierGenerationException：此类的ID必须在为字符串类型的ID调用save（）之前手动分配

Question

我在休眠持久性方面存在这个问题：org.hibernate.id.IdentifierGenerationException：此类的ID必须在调用save（）之前手动分配。这里有2个类，它们之间存在一对一的关系。我必须指定UserRole在MySql中成功创建，但是User没有。

@Entity
@Table(name = "user")
public class User {

    @Id
    private String id;

    @Column
    private String name;

    @Column
    private String email;

    @Column
    private String password;

    @OneToOne
    @JoinColumn(name = "userRole_id", referencedColumnName = "id")
    private UserRole userRole;

    public User() {
    }
@Entity
@Table(name = "userRole")
public class UserRole {

    @Id
    private String id;

    @Column
    private String description;

    @OneToOne(mappedBy = "userRole")
    private User user;

    public UserRole() {
    }
我有以下类UserRoleRepo和UserRepo

public class UserRepo {

    private EntityManagerFactory=
entityManagerFactoryPersistence.createEntityManagerFactory("tutorial.lab.SD");

    public void insertNewUser(User user) {
        EntityManager em = entityManagerFactory.createEntityManager();
        em.getTransaction().begin();
        em.persist(user); /////here I get the exception
        em.getTransaction().commit();
        em.close();
    }
}
public class UserRoleRepo {

    private EntityManagerFactory entityManagerFactory = Persistence.createEntityManagerFactory("ro.tutorial.lab.SD");

    public void insertNewUser(UserRole userRole) {
        EntityManager em = entityManagerFactory.createEntityManager();
        em.getTransaction().begin();
        em.persist(userRole);
        em.getTransaction().commit();
        em.close();
    }

}
整个应用程序都在此类中运行。我必须指定此模板，我必须遵循它。另外，每个类中的Id必须为String类型。

public class ApplicationStart {

    public static void main(String[] args) {
        UserRoleRepo userRoleRepo= new UserRoleRepo();

        UserRole userRole1 = new UserRole();
        userRole1.setId(UUID.randomUUID().toString());
        userRole1.setDescription("admin");
        userRoleRepo.insertNewUser(userRole1);

        UserRole userRole2 = new UserRole();
        userRole2.setId(UUID.randomUUID().toString());
        userRole2.setDescription("client");
        userRoleRepo.insertNewUser(userRole2);

        UserRepo userRepo= new UserRepo();
        User user = new User();
        user.setId(UUID.randomUUID().toString());
        user.setName("Todoran");
        user.setUserRole(userRole1);

        userRepo.insertNewUser(user);
    }

我在休眠持久性方面存在这个问题：org.hibernate.id.IdentifierGenerationException：此类的ID必须在调用save（）之前手动分配。这是2个类别，它们之间...

Answer 1

对于一对一关系，我认为映射是错误的。尝试进行以下更改。在用户表中输入：