java - Spring Data CrudRepository 应用自动级联类型

Question

在我的项目中，我必须连接到现有数据库并执行更新两个表的逻辑。

我的设置如下:

@Entity
@Table(name = "DOCUMENTCONTENT")
@Getter
public class DocumentContent {

    @Id
    @Column(name = "ID", insertable = false, updatable = false)
    private Long id;

    @OneToOne
    @JoinColumn(name = "DOCUMENT_ID", insertable = false, updatable = false)
    private Document document;

    @Lob
    @Column(name = "CONTENT")
    @Setter
    private byte[] content;
}

@Entity
@Table(name = "DOCUMENT")
@Getter
public class Document {

    @Id
    @Column(name = "ID", insertable = false, updatable = false)
    private Long id;

    @OneToOne(mappedBy = "document")
    private DocumentContent documentContent;

    @OneToMany(mappedBy = "document", fetch = EAGER)
    private List<Attachment> attachments;
}

@Entity
@Table(name = "ATTACHMENT")
@Getter
public class Attachment {

    @Id
    @Column(name = "ID")
    private Long id;

    @ManyToOne
    @JoinColumn(name = "DOCUMENT_ID", insertable = false, updatable = false)
    private Document document;

    @ManyToOne
    @JoinColumn(name = "CONTRACT_ID",updatable = false, insertable = false)
    private Contract contract;
}

@Entity
@Table(name = "CONTRACT")
@Getter
public class Contract {

    @Id
    @Column(name = "ID", insertable = false, updatable = false)
    private Long id;

    @Column(name = "STATUS")
    @Setter
    private String status;

    @ManyToOne
    @JoinColumn(name = "CUSTOMER_ID", insertable = false, updatable = false)
    private Customer customer;

    @OneToMany(mappedBy = "contract", fetch = EAGER)
    private List<Attachment> attachments;
}

@Service
public class MyServiceImpl implements MyService {

    @Autowired
    private DocumentContentRepository documentContentRepository; // spring data Crud Repository

    @Override
    @Transactional
    public void updateDocumentContent(SomeDto someDto) {
        DocumentContent documentContent = documentContentRepository.findByDocumentId(someDto.getDocumentId());
        documentContent.setContent(someDto.getBytes());
        List<Contract> contracts = documentContent.getDocument().getAttachments()
                .stream().map(Attachment::getContract).collect(toList());
        contracts.forEach(contract -> contract.setStatus("SIGNED"));
        documentContentRepository.save(documentContent);
    }
}

当我从上面的服务触发方法时，我可以注意到控制台输出中的那些 SQL:

Hibernate: update documentcontent set content=? where id=?
Hibernate: update contract set status=? where id=?

我明白为什么 jpa 在 documentcontent 表中执行第一次更新，但我不知道为什么它也在contract 表中更新。如您所见，我没有在任何实体中使用 CascadeType.MERGE。

您能解释一下为什么在没有声明级联类型的情况下执行了第二次更新吗？

Answer 1

我怀疑它与级联有任何关系，但与事务性写入机制( more info )有关。我相信你也可以摆脱这条线

documentContentRepository.save(documentContent);

因为您正在修改两个托管实体。在事务结束时，hibernate 会保留所有由脏检查机制 ( more info ) 标记为已修改的实体。