java - Hibernate:添加到列表的实体的ID

Question

我正在使用 Spring Data JPA + Hibernate。在将实体添加到其他实体的列表并保存后，我需要获取实体的 ID。这是代码:

@Entity
public class Product extends AbstractAuditable<Long> {


    @OneToMany(cascade = CascadeType.ALL, fetch = FetchType.LAZY)
    @JoinColumn(name = "product_id", nullable = false)
    private List<Feedback> feedbacks = new ArrayList<Feedback>();

    ...

}


@Entity
public class Feedback extends AbstractPersistable<Long> {

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "product_id", insertable = false, updatable = false, nullable = false)
    private Product product;

    ...

}


public interface ProductRepository extends JpaRepository<Product, Long> {

}


Feedback feedback = new Feedback();
product.getFeedbacks().add(feedback);
productRepository.saveProduct(product);
feedback.getId(); // returns null

反馈保存后如何正确获取ID？

Answer 1

您可以从 Hibernate Session 接口(interface)(或 EntityManager 接口(interface))执行刷新方法来“从底层数据库重新读取给定实例的状态”。示例:

session.save(object);
session.flush();
session.refresh(object);

您可以在此处找到更多信息:

• Hibernate calling get() after save() on the newly created record within the same transaction
• Hibernate: Refresh, Evict, Replicate and Flush
• Hibernate calling get() after save() on the newly created record within the same transaction
• Force refresh of collection JPA entityManager