EntityExistsException：具有相同标识符值的不同对象已与会话关联答案

【问题标题】：EntityExistsException: A different object with the same identifier value was already associated with the sessionEntityExistsException：具有相同标识符值的不同对象已与会话关联
【发布时间】：2021-09-24 18:12:11
【问题描述】：

我是地图新手，我相信这就是问题所在。这是我的一些代码。我只是添加了级联类型。因为我不确定要添加什么。我正在为 UsersTree 使用 BST 模型。每个节点有两个用户。我也不确定映射关系是否正确。这是我的用户实体：

    @Entity
@NoArgsConstructor
@AllArgsConstructor
@Data
@Table(name="Users")
public class User {
    @Id
    long pk;
    @OneToOne(cascade = CascadeType.ALL)
    UsersTree following;
    @OneToOne(cascade = CascadeType.ALL)
    UsersTree followers;
}

这是我的用户树：

@Entity
@AllArgsConstructor
@Data
@Table(name="UsersTree")
public class UsersTree {
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    long id;
    @OneToOne (cascade = {CascadeType.ALL})
    public Node root; //root of bst

}

这是我的节点树：

@Entity
@NoArgsConstructor
@AllArgsConstructor
@Data
@Table(name="Node")
public class Node{
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
long id;
@ManyToOne(cascade = {CascadeType.ALL},fetch = FetchType.LAZY)
User user; 
@OneToOne (cascade = {CascadeType.ALL})
UserInfo userInfo= new UserInfo();
//should i add a relationship here? like one to many?
@OneToOne (cascade = {CascadeType.ALL})
Node right, left;
    public Node(User user) {
        this.user=user;
        this.userInfo.date=new Date();
        this.userInfo.unfollowed=false;
        this.userInfo.disabled=false;
        left=right=null;
        
    }
}

在我的主要功能上，我只有一个使用 UserTree 的用户，我尝试使用它直接保存：

UserRepository.save(user);

这是错误消息的一部分：

javax.persistence.EntityExistsException: A different object with the same identifier value was already associated with the session : [com.instastalk.instastalk.model.User#22812749]
    at org.hibernate.internal.ExceptionConverterImpl.convert(ExceptionConverterImpl.java:123) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.internal.ExceptionConverterImpl.convert(ExceptionConverterImpl.java:181) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.internal.ExceptionConverterImpl.convert(ExceptionConverterImpl.java:188) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.internal.SessionImpl.firePersist(SessionImpl.java:750) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.internal.SessionImpl.persist(SessionImpl.java:712) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.engine.spi.CascadingActions$7.cascade(CascadingActions.java:298) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.engine.internal.Cascade.cascadeToOne(Cascade.java:499) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.engine.internal.Cascade.cascadeAssociation(Cascade.java:423) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.engine.internal.Cascade.cascadeProperty(Cascade.java:220) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.engine.internal.Cascade.cascade(Cascade.java:153) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.event.internal.AbstractSaveEventListener.cascadeBeforeSave(AbstractSaveEventListener.java:427) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.event.internal.AbstractSaveEventListener.performSaveOrReplicate(AbstractSaveEventListener.java:264) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.event.internal.AbstractSaveEventListener.performSave(AbstractSaveEventListener.java:193) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.event.internal.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:135) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.event.internal.DefaultPersistEventListener.entityIsTransient(DefaultPersistEventListener.java:185) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.event.internal.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:128) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.event.service.internal.EventListenerGroupImpl.fireEventOnEachListener(EventListenerGroupImpl.java:110) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.internal.SessionImpl.firePersist(SessionImpl.java:744) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.internal.SessionImpl.persist(SessionImpl.java:712) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.engine.spi.CascadingActions$7.cascade(CascadingActions.java:298) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.engine.internal.Cascade.cascadeToOne(Cascade.java:499) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.engine.internal.Cascade.cascadeAssociation(Cascade.java:423) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.engine.internal.Cascade.cascadeProperty(Cascade.java:220) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.engine.internal.Cascade.cascade(Cascade.java:153) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.event.internal.AbstractSaveEventListener.cascadeBeforeSave(AbstractSaveEventListener.java:427) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.event.internal.AbstractSaveEventListener.performSaveOrReplicate(AbstractSaveEventListener.java:264) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.event.internal.AbstractSaveEventListener.performSave(AbstractSaveEventListener.java:193) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.event.internal.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:135) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.event.internal.DefaultPersistEventListener.entityIsTransient(DefaultPersistEventListener.java:185) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.event.internal.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:128) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.event.service.internal.EventListenerGroupImpl.fireEventOnEachListener(EventListenerGroupImpl.java:110) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.internal.SessionImpl.firePersist(SessionImpl.java:744) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.internal.SessionImpl.persist(SessionImpl.java:712) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.engine.spi.CascadingActions$7.cascade(CascadingActions.java:298) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.engine.internal.Cascade.cascadeToOne(Cascade.java:499) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.engine.internal.Cascade.cascadeAssociation(Cascade.java:423) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.engine.internal.Cascade.cascadeProperty(Cascade.java:220) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.engine.internal.Cascade.cascade(Cascade.java:153) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.event.internal.AbstractSaveEventListener.cascadeBeforeSave(AbstractSaveEventListener.java:427) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.event.internal.AbstractSaveEventListener.performSaveOrReplicate(AbstractSaveEventListener.java:264) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.event.internal.AbstractSaveEventListener.performSave(AbstractSaveEventListener.java:193) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.event.internal.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:135) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.event.internal.DefaultPersistEventListener.entityIsTransient(DefaultPersistEventListener.java:185) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.event.internal.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:128) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.event.service.internal.EventListenerGroupImpl.fireEventOnEachListener(EventListenerGroupImpl.java:110) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.internal.SessionImpl.firePersist(SessionImpl.java:744) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.internal.SessionImpl.persist(SessionImpl.java:712) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.engine.spi.CascadingActions$7.cascade(CascadingActions.java:298) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.engine.internal.Cascade.cascadeToOne(Cascade.java:499) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.engine.internal.Cascade.cascadeAssociation(Cascade.java:423) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.engine.internal.Cascade.cascadeProperty(Cascade.java:220) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.engine.internal.Cascade.cascade(Cascade.java:153) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.event.internal.AbstractSaveEventListener.cascadeBeforeSave(AbstractSaveEventListener.java:427) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.event.internal.AbstractSaveEventListener.performSaveOrReplicate(AbstractSaveEventListener.java:264) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.event.internal.AbstractSaveEventListener.performSave(AbstractSaveEventListener.java:193) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.event.internal.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:135) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.event.internal.DefaultPersistEventListener.entityIsTransient(DefaultPersistEventListener.java:185) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.event.internal.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:128) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.event.service.internal.EventListenerGroupImpl.fireEventOnEachListener(EventListenerGroupImpl.java:110) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.internal.SessionImpl.firePersist(SessionImpl.java:744) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.internal.SessionImpl.persist(SessionImpl.java:712) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.engine.spi.CascadingActions$7.cascade(CascadingActions.java:298) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.engine.internal.Cascade.cascadeToOne(Cascade.java:499) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.engine.internal.Cascade.cascadeAssociation(Cascade.java:423) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.engine.internal.Cascade.cascadeProperty(Cascade.java:220) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.engine.internal.Cascade.cascade(Cascade.java:153) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.event.internal.AbstractSaveEventListener.cascadeBeforeSave(AbstractSaveEventListener.java:427) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.event.internal.AbstractSaveEventListener.performSaveOrReplicate(AbstractSaveEventListener.java:264) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.event.internal.AbstractSaveEventListener.performSave(AbstractSaveEventListener.java:193) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.event.internal.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:135) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.event.internal.DefaultPersistEventListener.entityIsTransient(DefaultPersistEventListener.java:185) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.event.internal.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:128) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.event.service.internal.EventListenerGroupImpl.fireEventOnEachListener(EventListenerGroupImpl.java:110) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.internal.SessionImpl.firePersist(SessionImpl.java:744) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.internal.SessionImpl.persist(SessionImpl.java:712) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.engine.spi.CascadingActions$7.cascade(CascadingActions.java:298) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.engine.internal.Cascade.cascadeToOne(Cascade.java:499) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.engine.internal.Cascade.cascadeAssociation(Cascade.java:423) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.engine.internal.Cascade.cascadeProperty(Cascade.java:220) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.engine.internal.Cascade.cascade(Cascade.java:153) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.event.internal.AbstractSaveEventListener.cascadeBeforeSave(AbstractSaveEventListener.java:427) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.event.internal.AbstractSaveEventListener.performSaveOrReplicate(AbstractSaveEventListener.java:264) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.event.internal.AbstractSaveEventListener.performSave(AbstractSaveEventListener.java:193) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.event.internal.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:135) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.event.internal.DefaultPersistEventListener.entityIsTransient(DefaultPersistEventListener.java:185) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.event.internal.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:128) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.event.service.internal.EventListenerGroupImpl.fireEventOnEachListener(EventListenerGroupImpl.java:110) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.internal.SessionImpl.firePersist(SessionImpl.java:744) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.internal.SessionImpl.persist(SessionImpl.java:712) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.engine.spi.CascadingActions$7.cascade(CascadingActions.java:298) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.engine.internal.Cascade.cascadeToOne(Cascade.java:499) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.engine.internal.Cascade.cascadeAssociation(Cascade.java:423) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.engine.internal.Cascade.cascadeProperty(Cascade.java:220) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.engine.internal.Cascade.cascade(Cascade.java:153) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.event.internal.AbstractSaveEventListener.cascadeBeforeSave(AbstractSaveEventListener.java:427) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.event.internal.AbstractSaveEventListener.performSaveOrReplicate(AbstractSaveEventListener.java:264) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.event.internal.AbstractSaveEventListener.performSave(AbstractSaveEventListener.java:193) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.event.internal.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:135) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.event.internal.DefaultPersistEventListener.entityIsTransient(DefaultPersistEventListener.java:185) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.event.internal.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:128) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.event.service.internal.EventListenerGroupImpl.fireEventOnEachListener(EventListenerGroupImpl.java:110) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.internal.SessionImpl.firePersist(SessionImpl.java:744) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.internal.SessionImpl.persist(SessionImpl.java:712) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.engine.spi.CascadingActions$7.cascade(CascadingActions.java:298) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.engine.internal.Cascade.cascadeToOne(Cascade.java:499) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.engine.internal.Cascade.cascadeAssociation(Cascade.java:423) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.engine.internal.Cascade.cascadeProperty(Cascade.java:220) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.engine.internal.Cascade.cascade(Cascade.java:153) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.event.internal.AbstractSaveEventListener.cascadeBeforeSave(AbstractSaveEventListener.java:427) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.event.internal.AbstractSaveEventListener.performSaveOrReplicate(AbstractSaveEventListener.java:264) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.event.internal.AbstractSaveEventListener.performSave(AbstractSaveEventListener.java:193) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.event.internal.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:135) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.event.internal.DefaultPersistEventListener.entityIsTransient(DefaultPersistEventListener.java:185) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.event.internal.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:128) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.event.service.internal.EventListenerGroupImpl.fireEventOnEachListener(EventListenerGroupImpl.java:110) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.internal.SessionImpl.firePersist(SessionImpl.java:744) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.internal.SessionImpl.persist(SessionImpl.java:712) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.engine.spi.CascadingActions$7.cascade(CascadingActions.java:298) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.engine.internal.Cascade.cascadeToOne(Cascade.java:499) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.engine.internal.Cascade.cascadeAssociation(Cascade.java:423) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.engine.internal.Cascade.cascadeProperty(Cascade.java:220) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.engine.internal.Cascade.cascade(Cascade.java:153) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.event.internal.AbstractSaveEventListener.cascadeBeforeSave(AbstractSaveEventListener.java:427) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.event.internal.AbstractSaveEventListener.performSaveOrReplicate(AbstractSaveEventListener.java:264) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.event.internal.AbstractSaveEventListener.performSave(AbstractSaveEventListener.java:193) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.event.internal.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:135) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.event.internal.DefaultPersistEventListener.entityIsTransient(DefaultPersistEventListener.java:185) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.event.internal.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:128) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.event.service.internal.EventListenerGroupImpl.fireEventOnEachListener(EventListenerGroupImpl.java:110) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.internal.SessionImpl.firePersist(SessionImpl.java:744) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.internal.SessionImpl.persist(SessionImpl.java:712) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.engine.spi.CascadingActions$7.cascade(CascadingActions.java:298) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.engine.internal.Cascade.cascadeToOne(Cascade.java:499) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.engine.internal.Cascade.cascadeAssociation(Cascade.java:423) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.engine.internal.Cascade.cascadeProperty(Cascade.java:220) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.engine.internal.Cascade.cascade(Cascade.java:153) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.event.internal.AbstractSaveEventListener.cascadeBeforeSave(AbstractSaveEventListener.java:427) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.event.internal.AbstractSaveEventListener.performSaveOrReplicate(AbstractSaveEventListener.java:264) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.event.internal.AbstractSaveEventListener.performSave(AbstractSaveEventListener.java:193) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.event.internal.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:135) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.event.internal.DefaultPersistEventListener.entityIsTransient(DefaultPersistEventListener.java:185) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.event.internal.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:128) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.event.internal.DefaultPersistEventListener.onPersist(DefaultPersistEventListener.java:55) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.event.service.internal.EventListenerGroupImpl.fireEventOnEachListener(EventListenerGroupImpl.java:99) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.internal.SessionImpl.firePersist(SessionImpl.java:720) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at org.hibernate.internal.SessionImpl.persist(SessionImpl.java:706) ~[hibernate-core-5.4.32.Final.jar:5.4.32.Final]
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na]
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:na]
    at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:na]
    at java.base/java.lang.reflect.Method.invoke(Method.java:567) ~[na:na]
    at org.springframework.orm.jpa.ExtendedEntityManagerCreator$ExtendedEntityManagerInvocationHandler.invoke(ExtendedEntityManagerCreator.java:362) ~[spring-orm-5.3.8.jar:5.3.8]
    at com.sun.proxy.$Proxy166.persist(Unknown Source) ~[na:na]
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na]
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:na]
    at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:na]
    at java.base/java.lang.reflect.Method.invoke(Method.java:567) ~[na:na]
    at org.springframework.orm.jpa.SharedEntityManagerCreator$SharedEntityManagerInvocationHandler.invoke(SharedEntityManagerCreator.java:311) ~[spring-orm-5.3.8.jar:5.3.8]
    at com.sun.proxy.$Proxy166.persist(Unknown Source) ~[na:na]
    at org.springframework.data.jpa.repository.support.SimpleJpaRepository.save(SimpleJpaRepository.java:597) ~[spring-data-jpa-2.5.2.jar:2.5.2]
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na]
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:na]
    at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:na]
    at java.base/java.lang.reflect.Method.invoke(Method.java:567) ~[na:na]
    at org.springframework.data.repository.core.support.RepositoryMethodInvoker$RepositoryFragmentMethodInvoker.lambda$new$0(RepositoryMethodInvoker.java:289) ~[spring-data-commons-2.5.2.jar:2.5.2]
    at org.springframework.data.repository.core.support.RepositoryMethodInvoker.doInvoke(RepositoryMethodInvoker.java:137) ~[spring-data-commons-2.5.2.jar:2.5.2]
    at

还有更多...

【问题讨论】：

标签： spring-boot hibernate hibernate-mapping

【解决方案1】：

显然，一个 id 为 1 的节点 N1 通过一系列节点，通过 left/right 关联，指向同样具有 id 1 但为 N1 != Nx 的节点 Nx。这不可能。如果要写这样的循环图，就得用同一个对象N1。

【讨论】：

我从错误中了解到的是两个用户具有相同的 id (pk) 而不是节点。每次创建节点时，它们都有唯一的 ID：@GeneratedValue(strategy = GenerationType.AUTO) long id;
你说得对，我没看那么仔细。但是问题是一样的，通过一些左/右节点可以访问这样的用户。