Question

我的问题不是“ mappedBy”的工作方式。我知道，仅表明关系的所有者。我的问题是orphanRemoval如何工作。在我的情况下，我根本不使用“ mappedBy”指示。

我有以下实体：

@Entity
@Table(name = "catalog_orphan")
public class CatalogOrphan extends AbstractBaseEntity<Long> {

    @OneToMany(orphanRemoval = true)
    private List<GoodOrphan> goodOrphans;

    public List<GoodOrphan> getGoodOrphans() {
        return goodOrphans;
    }

    public void setGoodOrphans(List<GoodOrphan> goodOrphans) {
        this.goodOrphans = goodOrphans;
    }
}

@Entity
@Table(name = "good_orphan")
public class GoodOrphan extends AbstractBaseEntity<Long> {

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "catalog_orphan_id")
    private CatalogOrphan catalogOrphan;

    public CatalogOrphan getCatalogOrphan() {
        return catalogOrphan;
    }

    public void setCatalogOrphan(CatalogOrphan catalogOrphan) {
        this.catalogOrphan = catalogOrphan;
    }
}

@MappedSuperclass
public abstract class AbstractBaseEntity<ID> {

    @Id
    @Column
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    protected ID id;

    @Column(name = "name")
    protected String name;
}

我正在尝试测试删除孤儿的功能。

我编写了以下测试：

@RunWith(SpringRunner.class)
@DataJpaTest
@TestExecutionListeners({
        TransactionalTestExecutionListener.class,
        DependencyInjectionTestExecutionListener.class,
        DbUnitTestExecutionListener.class
})
@DatabaseSetup("/persistCascade/orphan/catalog_good_orphan.xml")
public class CatalogOrphanTest {

    @Autowired
    protected TestEntityManager entityManager;

    @Test
    public void clearCollections() {
        CatalogOrphan catalog = entityManager.find(CatalogOrphan.class, 1L);

        catalog.getGoodOrphans().clear();
        entityManager.persist(catalog);

        entityManager.flush();
        entityManager.clear();

        CatalogOrphan catalogAfterCleanCollection2 = entityManager.find(CatalogOrphan.class, 1L);
        assertThat(catalogAfterCleanCollection2.getGoodOrphans().size(), equalTo(0)); // Does this mean that the connection has been deleted?

        GoodOrphan goodOrphan = entityManager.find(GoodOrphan.class, 1L);
        assertThat(goodOrphan.getCatalogOrphan(), is(notNullValue()));  // WHY???
    }
}

catalog_good_orphan.xml：

<dataset>
    <Catalog_Orphan id="1" name="Catalog#1"/>
    <Catalog_Orphan id="2" name="Catalog#2"/>

    <Good_Orphan id="1" name="Good#1" catalog_orphan_id="1"/>
    <Good_Orphan id="2" name="Good#2" catalog_orphan_id="1"/>
    <Good_Orphan id="3" name="Good#3" catalog_orphan_id="2"/>
    <Good_Orphan id="4" name="Good#4" catalog_orphan_id="2"/>

    <!-- without catalog -->
    <Good_Orphan id="5" name="Good#5" />
</dataset>

我根本不明白“ orphanRemoval = true”的意义。他为什么这样工作？结果，我们仅从“ CatalogOrphan”中删除了指向“ GoodOrphan”的链接，而保留了从“ GoodOrphan”至“ CatalogOrphan”的链接。

我在做什么错？还是这是正确的行为？

Answer 1

removeOrphan当不再与父项链接时，会将其从数据库中删除。仅当您在同一会话中从列表中删除该项目时，它才起作用。注意：从列表中删除和从项目中删除对父项的引用是两个不同的事情，即使您（应该）在数据库中为这两个引用使用相同的外键。

注意：当您从一个列表中删除一个项目并将其添加到另一个列表时，此功能不起作用。幸运的话，您会收到一个异常消息，告诉您它不起作用。

有人可以在Hibernate中解释orphanRemoval吗？

1 个答案: