保存具有一對多和客戶端分配id的物體時出現JpaObjectRetrievalFailureException

JpaObjectRetrievalFailureException在一個簡單的 Spring Boot 應用程式中，當我嘗試使用一對多關聯和客戶端分配的 id 保存物體時，我面臨著一個問題。

請查看這些物體和這個簡單的存盤庫：

@Entity
@Table(name = "cart")
public class Cart {
    @Id
    @Column(name = "id")
    private UUID id;

    @Column(name = "name")
    private String name;

    @OneToMany
    @JoinColumn(name = "cart_id")
    private List<Item> items;

    // constructors, getters, setters, equals and hashCode ommitted
}

@Entity
@Table(name = "item")
public class Item {
    @Id
    @Column(name = "id")
    private UUID id;
    @Column(name = "name")
    private String name;

    // constructors, getters, setters, equals and hashCode ommitted
}

public interface CartRepository extends JpaRepository<Cart, UUID> {
}

我寫了這個測驗：

@DataJpaTest
class CartRepositoryTest {

    @Autowired
    private CartRepository cartRepository;

    @Test
    void should_save_cart() {
        // GIVEN
        final var cart = new Cart(UUID.randomUUID(), "cart");
        final var item = new Item(UUID.randomUUID(), "item");
        cart.setItems(List.of(item));

        // WHEN
        final var saved = cartRepository.save(cart);

        // THEN
        final var fetched = cartRepository.findById(saved.id());
        assertThat(fetched).isPresent();
    }
}

當我運行測驗時，呼叫cartRepository.save(cart)失敗并顯示：

Unable to find com.example.testjpaonetomany.domain.Item with id f5658508-f3d0-4d9b-a1f0-17b614753356; nested exception is javax.persistence.EntityNotFoundException: Unable to find com.example.testjpaonetomany.domain.Item with id f5658508-f3d0-4d9b-a1f0-17b614753356
org.springframework.orm.jpa.JpaObjectRetrievalFailureException: Unable to find com.example.testjpaonetomany.domain.Item with id f5658508-f3d0-4d9b-a1f0-17b614753356; nested exception is javax.persistence.EntityNotFoundException: Unable to find com.example.testjpaonetomany.domain.Item with id f5658508-f3d0-4d9b-a1f0-17b614753356
    at app//org.springframework.orm.jpa.EntityManagerFactoryUtils.convertJpaAccessExceptionIfPossible(EntityManagerFactoryUtils.java:379)
    at app//org.springframework.orm.jpa.vendor.HibernateJpaDialect.translateExceptionIfPossible(HibernateJpaDialect.java:235)
    at app//org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.translateExceptionIfPossible(AbstractEntityManagerFactoryBean.java:551)
    at app//org.springframework.dao.support.ChainedPersistenceExceptionTranslator.translateExceptionIfPossible(ChainedPersistenceExceptionTranslator.java:61)
    at app//org.springframework.dao.support.DataAccessUtils.translateIfNecessary(DataAccessUtils.java:242)
    at app//org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:152)
    at app//org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
    at app//org.springframework.data.jpa.repository.support.CrudMethodMetadataPostProcessor$CrudMethodMetadataPopulatingMethodInterceptor.invoke(CrudMethodMetadataPostProcessor.java:174)
    at app//org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
    at app//org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:97)
    at app//org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
    at app//org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:215)
    at app/jdk.proxy3/jdk.proxy3.$Proxy105.save(Unknown Source)
    at app//com.example.testjpaonetomany.repository.CartRepositoryTest.should_save_cart(CartRepositoryTest.java:28)

如果我通過添加 for id 來修改我的物體@GeneratedValue，并且在我的測驗中，我替換UUID.randomUUID()為null將 ID 生成委托給 Hibernate，則測驗通過。

如何處理客戶端生成的 id？

uj5u.com熱心網友回復：

原因是您僅保存父物件（這絕對正確且很好）但仍需要解釋 JPA 應該傳播該操作，即

@OneToMany(cascade = CascadeType.ALL, orphanRemoval = true)
@JoinColumn(name = "cart_id")
private List<Item> items;

作為小的改進，我建議將 UUID 生成放入建構式中并通過專用方法建立關系，即

final var cart = new Cart("cart");
cart.addItem(new Item("item"));

并且可能考慮使用em.persist()而不是repository.save()因為它select首先發出請求，以防@Augusto 提到的使用uuids

標籤：爪哇弹簧靴休眠jpa

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