[英]Updating a child object in a save cascade result in ConstraintViolationException using spring data repository
I am new to Spring Data and I want to know how to update the child objects when I save the parent object. 我是Spring Data的新手,我想知道在保存父对象时如何更新子对象。
Pojo: Pojo:
@Entity
@Table(name = "A")
public final class A {
@Id
@Column(name = "A_ID")
private Long id;
@ManyToOne(cascade = CascadeType.ALL)
@JoinColumn(name = "B_ID")
private B b;
}
@Entity
@Table(name = "B")
public final class B {
@Id
@Column(name = "B_ID")
private Long id;
@Column(name = "B_NAME")
private String bName;
}
The repository: 仓库:
public interface ARepository extends JpaRepository<A, Long> {
}
And the unit test: 和单元测试:
@Test
public void testSaveA() {
B b = new B();
b.setId(1L);
b.setName("b");
A a = new A();
a.setB(b);
//If b already exists in database then ConstraintViolationException
ARepository.save(b);
}
So the issue here is that it's trying to insert b
instead of updating it. 因此,这里的问题是它试图插入b
而不是对其进行更新。 Is it possible to use cascade to update it? 是否可以使用级联对其进行更新?
First of all, you have to persist any attached objects withint a @Transactional
. 首先,您必须在@Transactional
保留所有附加对象。 Then you must fetch the child, and if it exists assign the existing child to A
, otherwise create a new one. 然后,您必须获取该子项,如果存在,则将现有子项分配给A
,否则创建一个新的子项。
@Transactional()
public void update() {
B b = ARepository.find(1L);
if (b == null) b = new B();
//update etc
}
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.