保存后刷新并获取实体（JPA/Spring Data/Hibernate）

我有这两个简单的实体和.该实体与 具有多对一关系，因此当我创建新行时，我会分配一个现有的 .SomethingPropertySomethingPropertySomethingProperty

东西：

@Entity
@Table(name = "something")
public class Something implements Serializable {

    private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

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

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

    @ManyToOne
    private Property property;

    // getters and setters

    @Override
    public String toString() {
        return "Something{" +
            "id=" + getId() +
            ", name='" + getName() + "'" +
            ", owner='" + getOwner() + "'" +
            ", property=" + getProperty() +
            "}";
    }

财产：

@Entity
@Table(name = "property")
public class Property implements Serializable {

    private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

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

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

    @Column(name = "dimension")
    private Integer dimension;

    // getters and setters

    @Override
    public String toString() {
        return "Property{" +
            "id=" + getId() +
            ", shape='" + getShape() + "'" +
            ", color='" + getColor() + "'" +
            ", dimension='" + getDimension() + "'" +
            "}";
    }
}

这是（春天）：SomethingRepository

@SuppressWarnings("unused")
@Repository
public interface SomethingRepository extends JpaRepository<Something,Long> {
    
}

通过REST控制器和JSON，我想创建一个新的：Something

@RestController
@RequestMapping("/api")
public class SomethingResource {

    private final SomethingRepository somethingRepository;

    public SomethingResource(SomethingRepository somethingRepository) {
        this.somethingRepository = somethingRepository;
    }

    @PostMapping("/somethings")
    public Something createSomething(@RequestBody Something something) throws URISyntaxException {
        Something result = somethingRepository.save(something);
        return result;
    }
}

这是输入中的 JSON（1 是数据库中的现有行）：propertyid

{
  "name": "MyName",
  "owner": "MySelf",
  "property": {
    "id": 1
  }

}

问题是：在方法之后，变量包含持久化实体，但没有字段的字段，已验证（它们是）：.save(something)resultpropertynull

输出 JSON：

{
  "id": 1,
  "name": "MyName",
  "owner": "MySelf",
  "property": {
    "id": 1,
    "shape": null,
    "color": null,
    "dimension": null
  }
}

我希望它们在保存操作后被验证/返回。

为了解决这个问题，我必须在REST控制器中注入/声明，并调用该方法（或者我必须调用一个方法才能获得完整的持久化实体）：EntityManagerEntityManager.refresh(something).findOne(something.getId())

@RestController
@RequestMapping("/api")
@Transactional
public class SomethingResource {

    private final SomethingRepository somethingRepository;
    
    private final EntityManager em;

    public SomethingResource(SomethingRepository somethingRepository, EntityManager em) {
        this.somethingRepository = somethingRepository;
        this.em = em;
    }

    @PostMapping("/somethings")
    public Something createSomething(@RequestBody Something something) throws URISyntaxException {
        Something result = somethingRepository.save(something);
        em.refresh(result);
        return result;
    }
}

有了这个解决方法，我得到了预期的保存（使用正确的JSON）：

{
  "id": 4,
  "name": "MyName",
  "owner": "MySelf",
  "property": {
    "id": 1,
    "shape": "Rectangle",
    "color": "Red",
    "dimension": 50
  }
}

有没有一个自动的方法/注释，JPA或Spring或Hibernate，以便拥有“完整”的持久化实体？

我希望避免在每个 REST 或 Service 类中声明 the，或者我想避免每次需要新的刷新持久化实体时调用该方法。EntityManager.findOne(Long)