Java Hibernate + spring-data : Cascading Childs not working when Parent is persistent

Question

我有父子关系，当我尝试通过父级更新添加新子级时，我的问题就出现了。

当我的 parent 短暂时，一切正常

    CreditCard cc = new CreditCard("1234");

    //User
    User u1 = new User("KILLER");
    u1.addCreditCard(cc); // bi-directional happens here inside.

    // An autowired Spring Data repository that implements CrudRepository
    userRepository.save(u1);

    Assert.assertEquals(1, u1.getCreditCardCollection().size());
    Assert.assertNotNull
    (
            u1.getCreditCardCollection()
            .stream()
            .findFirst()
            .get()
            .getIdCreditCard()
    );

以上测试已成功执行，并为 cc 对象生成了 ID。

但是当我这样做时:

    User u2 = new User("Foo Bar McLoud"); // u2 is transient

    userRepository.save(u2); // Now u2 is persistent

    u2 = userRepository.findOne(u2.getIdLogin());// just to be sure I´m working with a persistent object ;)

    CreditCard ccNew = new CreditCard("77777");

    u2.addCreditCard(ccNew );// bidirectional happens here inside

    userRepository.save(u2); // should insert a new credit card right???

    Assert.assertEquals("User should have 1 credit card.",
            1, u2.getCreditCardCollection().size()); // PASS

    Set<CreditCard> ccs = u2.getCreditCardCollection();
    for (CreditCard cc : ccs) {
        Assert.assertNotNull("CreditCard ID is null", cc.getIdCreditCard()); // FAIL: id is not generated. The database entry was not set. Added credit card is still transient... 
    }

因此，在我的第二次测试中，我的 ccNew 在其父级更新后仍然是暂时的。

为什么它仍然是短暂的？

子配置:

@JoinColumn(name = "id_user")
@ManyToOne(optional = false)
private User user;

父配置:

@OneToMany(mappedBy = "user")
@org.hibernate.annotations.Cascade(org.hibernate.annotations.CascadeType.ALL)
private Set<CreditCard> creditCardCollection = new HashSet<>();

已经在父级上尝试过:

    @OneToMany(mappedBy = "user",cascade=javax.persistence.CascadeType.ALL)
    private Set<CreditCard> creditCardCollection = new HashSet<>();

Answer 1

您在一个事务中测试工作，在此您使用 (u2.getCreditCardCollection()) 使用对象中的值而不是实体中的值(尚未执行保存):

Assert.assertEquals("User should have 2 credit cards.", 1, u2.getCreditCardCollection().size());

当您迭代 u2.getCreditCardCollection() 并检查 id 时，它们为 null，因为插入和 id 生成仅在提交阶段或刷新/清除上下文中进行。

您需要调用 saveAndFlush() 而不是只调用 save()。

    u2 = userRepository.findOne(u2.getIdLogin());

    CreditCard ccNew = new CreditCard("77777");

    u2.addCreditCard(ccNew );// bidirectional happens here inside

    userRepository.saveAndFlush(u2); 

    Assert.assertEquals("User should have 2 credit cards.",
            1, u2.getCreditCardCollection().size()); // PASS

    Set<CreditCard> ccs = u2.getCreditCardCollection();
    for (CreditCard cc : ccs) {
        Assert.assertNotNull("CreditCard ID is null", cc.getIdCreditCard());
    }

来自 API；

void flush() Flushes all pending changes to the database.

S saveAndFlush(S entity) Saves an entity and flushes changes instantly