Question

我有两个可持久的实体Obj1和Obj2。 Obj2包含对Obj的引用，如下所示。在Obj1中没有对Obj2的引用（在代码级别 - Java）。

public class Obj2{
....
@ManyToOne(cascade = {CascadeType.PERSIST, CascadeType.MERGE, CascadeType.REFRESH, CascadeType.REMOVE}, optional = true)
private Obj1 obj1;

我按照建议用@OneToMany更新了Ojbj 1：

public class Obj1{

....

    @OneToMany(cascade = {CascadeType.PERSIST, CascadeType.MERGE, CascadeType.REFRESH, CascadeType.REMOVE,CascadeType.ALL},orphanRemoval = true)
    private List<Obj2> obj2;

当我尝试删除Obj1时：

em.remove(obj1Instance)

由于Foreigh Key constaint

而失败

00:35:23,109 WARN  [com.arjuna.ats.arjuna] (http--127.0.0.1-8080-1) ARJUNA012125: TwoPhaseCoordinator.beforeCompletion - failed for SynchronizationImple< 0:ffff7f000101:-7f20c644:5369716f:26, org.hibernate.engine.transaction.synchronization.internal.RegisteredSynchronization@dcedf7 >: javax.persistence.PersistenceException: org.hibernate.exception.ConstraintViolationException: Cannot delete or update a parent row: a foreign key constraint fails (`my_db`.`obj2`, CONSTRAINT `FKC4783505BB5D6339` FOREIGN KEY (`obj1_pk`) REFERENCES `obj1` (`pk`))
...
... 94 more
Caused by: org.hibernate.exception.ConstraintViolationException: Cannot delete or update a parent row: a foreign key constraint fails (`my_db`.`obj2`, CONSTRAINT `FKC4783505BB5D6339` FOREIGN KEY (`obj1_pk`) REFERENCES `obj1` (`pk`))

Caused by: com.mysql.jdbc.exceptions.jdbc4.MySQLIntegrityConstraintViolationException: Cannot delete or update a parent row: a foreign key constraint fails (`my_db`.`obj2`, CONSTRAINT `FKC4783505BB5D6339` FOREIGN KEY (`obj1_pk`) REFERENCES `obj1` (`pk`))

我（错误地看来！）认为CascadeType.REMOVE会照顾这个？我该如何处理这个删除？

/ T

Answer 1

手动处理或在Obj1中添加反向关系@OneToMany(orphanRemoval=true)。

Answer 2

感谢帮助人员...我设法通过（某种程度）结合两条建议并改变了外键，以便在DELETE上进行CASCADE。

Answer 3

您何时添加optional = true？是在部署应用程序之前还是之后？如果是之后，MySQL将不会更新my_db。obj2上的NotNull约束，检查列obj1_pk是否为Nullable。如果不是，请删除并添加约束obj1_pk，使其可以为Nullable。或者你可以简单地删除这两个表并重新创建它们。

Hibernate：无法删除对象 - 外键约束 - CascadeType.REMOVE

3 个答案: