[英]Hibernate OneToOne attempted to assign id from null one-to-one property
我正在嘗試在 2 個實體之間創建一對一的關系,其中“子”被“父”ID 引用為外鍵。 這是我的 2 個實體:
@Entity
@Table(name = "users")
public class User extends PanacheEntityBase implements Serializable {
@Id
@GeneratedValue(generator = "UUID")
@GenericGenerator(name = "UUID", strategy = "org.hibernate.id.UUIDGenerator")
String id;
@OneToOne(mappedBy = "user", cascade = CascadeType.ALL , optional = false)
Profile profile;
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public Profile getProfile() {
return profile;
}
public void setProfile(Profile profile) {
this.profile = profile;
}
}
和
@Entity
@Table(name = "profiles")
public class Profile extends PanacheEntityBase implements Serializable {
@GenericGenerator(name = "generator", strategy = "foreign", parameters = @Parameter(name = "property", value = "user"))
@Id
@GeneratedValue(generator = "generator")
@Column(name = "user_id")
String id;
@OneToOne
@MapsId
@JoinColumn(name = "user_id")
User user;
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public User getUser() {
return user;
}
public void setUser(User user) {
this.user = user;
}
}
在保存時,我構建對象並將其持久化:
User user = new User();
Profile profile = new Profile();
user.setProfile(profile);
userRepository.persist(user);
但我收到這個錯誤
org.jboss.resteasy.spi.UnhandledException:javax.persistence.PersistenceException:org.hibernate.id.IdentifierGenerationException:試圖從空一對一屬性[com.myne.entities.Profile.user]分配id
我究竟做錯了什么?
所以經過更多的研究,我終於能夠解決這個問題。 我在這 3 個帖子之間使用了混合
https://howtodoinjava.com/hibernate/hibernate-one-to-one-mapping/
https://stackoverflow.com/a/52010963/3353167
https://stackoverflow.com/a/18622821/3353167
正如第一篇文章所建議的,使用@MapsId 會讓休眠知道子實體將共享父實體的 id。 所以我改變了我的課程:
@Entity
@Table(name = "users")
public class User extends PanacheEntityBase implements Serializable {
@Id
@GeneratedValue(generator = "UUID")
@GenericGenerator(name = "UUID", strategy = "org.hibernate.id.UUIDGenerator")
String id;
@OneToOne
@MapsId
Profile profile;
...
和
@Entity
@Table(name = "profiles")
public class Profile extends PanacheEntityBase implements Serializable {
@Id
@Column(name = "user_id")
String id;
// removed the User Column
...
然后問題來自使用 GenerationType.Auto 的 Hibernate,如第三篇文章中所建議的。 因此,為了指示 Hibernate 生成 UUID,我按照第二篇文章中的示例將 Profile id 更改為如下所示:
@GeneratedValue(generator = "UUID")
@GenericGenerator(name = "UUID", strategy = "org.hibernate.id.UUIDGenerator")
@Column(name = "user_id", updatable = false, nullable = false)
@Id
String id;
...
它就像一個魅力。 我希望它可以幫助將來遇到同樣問題的其他人
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