如何通过JPA/Hibernate/Spring Boot独立更新嵌套实体的更新字段

我有一对一对一关联的嵌套实体EntityA和EntityB，需求是仅当实体自身字段发生变更时，独立更新该实体的username和lastUpdateDatetime，关联实体的对应字段不更新：

• 若EntityB自身字段变更，仅更新EntityB的username和lastUpdateDatetime
• 若EntityA自身字段变更，仅更新EntityA的username和lastUpdateDatetime

实体代码 #

EntityA #

@Entity(name = "EntityA")
public class EntityA {
    
    @Column(name = "EntityAColumn1")
    private String entityAColumn1;

    @Column(name = "EntityAColumn2")
    private String entityAColumn2;     

    @OneToOne(cascade = CascadeType.ALL)
    @JoinColumn(name = "EntityA_EntityB")
    private EntityB entityB;

    @Column(name = "username", length = 100)
    private String username;

    @Column(name = "last_update_datetime")
    private ZonedDateTime lastUpdateDatetime;
}

EntityB #

@Entity(name = "EntityB")
public class EntityB {
    
    @Column(name = "EntityBColumn1")
    private String entityBColumn1;

    @Column(name = "EntityBColumn2")
    private String entityBColumn2;     

    @OneToOne(cascade = CascadeType.ALL, mappedBy = "EntityB", fetch = FetchType.LAZY)
    private EntityA entityA;

    @Column(name = "username", length = 100)
    private String username;

    @Column(name = "last_update_datetime")
    private ZonedDateTime lastUpdateDatetime;
}

控制器代码 #

@RestController
public class EntityAController {

    private final EntityARepository entityARepository;

    @PutMapping("/update")
    public void updateEntityA(
        @RequestBody ObjectA objectA,
        @RequestHeader("username") String username
    ) {
        EntityA entityA = EntityMapper.mapToEntity(objectA);

        entityARepository.save(entityA);
    }
}

注：EntityMapper.mapToEntity(objectA)仅用于将Web请求映射为实体

仓库代码 #

@Repository("EntityARepository")
public interface ShippingOrderRepository extends CrudRepository<EntityA, Long> {
    
}

数据示例 #

更新前数据库数据（JSON格式便于阅读） #

{
    "entityAColumn1": "val1",
    "entityAColumn2": "val2",
    "entityB": {
        "entityBColumn1": "val3",
        "entityBColumn2": "val4",
        "username": "username1",
        "lastUpdateDatetime": "2023-09-20T07:09:30Z"
    },
    "username": "username1",
    "lastUpdateDatetime": "2023-09-20T07:09:30Z"
}

更新请求内容 #

{
    "entityAColumn1": "val1",
    "entityAColumn2": "val2",
    "entityB": {
        "entityBColumn1": "val3",
        "entityBColumn2": "val5", // 值已变更
        "username": "username1",
        "lastUpdateDatetime": "2023-09-20T07:09:30Z"
    },
    "username": "username1",
    "lastUpdateDatetime": "2023-09-20T07:09:30Z"
}

• 仅EntityB的entityBColumn2字段发生变更
• 请求头中的username为"username2"

期望更新结果 #

{
    "entityAColumn1": "val1",
    "entityAColumn2": "val2",
    "entityB": {
        "entityBColumn1": "val3",
        "entityBColumn2": "val5", // 已更新
        "username": "username2", // 已更新
        "lastUpdateDatetime": "2023-10-13T07:09:30Z" // 已更新
    },
    "username": "username1",
    "lastUpdateDatetime": "2023-09-20T07:09:30Z"
}

仅EntityB的username和lastUpdateDatetime被更新，因其是唯一发生变更的实体

已尝试的无效方案 #

1. 使用@PreUpdate注解方法：即使仅一个实体变更，两个实体的审计字段都会被更新

@PreUpdate
public void preUpdate() {
    this.username = UsernameUtil.getUserName();
    this.lastUpdateDatetime = ZonedDateTime.now();
}

2. 使用@UpdateTimestamp注解更新lastUpdateDatetime：同样会导致两个实体的对应字段都被更新

@UpdateTimestamp
@Column(name = "last_update_datetime")
private ZonedDateTime lastUpdateDatetime;

注：已实现从请求头获取并存储username的机制，此处省略相关代码

核心问题 #

是否存在JPA/Hibernate原生机制，能够实现仅当实体自身字段变更时独立更新其username和lastUpdateDatetime，无需编写大量字段对比方法（实体字段较多时该方式不切实际）？

内容的提问来源于stack exchange，提问作者Vanblerk Havenga