java - 仅使用业务 key 保存对象。 [ hibernate ]

Question

嗨，我有一个任务，我想保存一些 ParentObject，但是这个 ParentObject 通过表上的 PK 与 ChildrenObject 相关。但按照我的逻辑，我没有 PK 唯一的业务 key (代码)。当我只有业务 key (代码)时，我的问题是如何用这个childrenObject的FK保存parenObject。 (业务键是唯一的，就像子表中的PK一样)。

我可以通过业务 key 获取childrenTable 来手动完成此操作，然后更新与parentObject 相关的PK 女巫。但我认为这很愚蠢，我希望 Hibernate 可以为我做到这一点。

代码:

@Entity
@Table(name = "parent_object")
public class ParenObject {
@Id
    private Integer id;

    @NaturalId
    @Column(name = "code", unique = true, nullable = false)
    private String code;

    @Column(name = "name", unique = true, nullable = false)
    private String name;

    @ManyToOne
    @JoinColumn(name = "children_id")
    private ChildrenObject childrenObject;
}

@Entity
@Table(name = "children_object")
public class ChildrenObject {
@Id
    private Integer id;

    @NaturalId
    @Column(name = "code", unique = true, nullable = false)
    private String code;

    @Column(name = "name", unique = true, nullable = false)
    private String name;

}

使用 CRUD 存储库，我只想简单地保存该对象:

{ "id": null,
"code": "12345",
"name": "Parent Entity",
"childrenObject": {
 "id":null,
 "code":"09876",
 "name": "Children Entity"
 }
}

Answer 1

不幸的是，您似乎必须先获取它。正如 The best way to map a @NaturalId business key with JPA and Hibernate 中提到的:

Hibernate already has a well-established logic for loading and associating entities by their identifier in the Persistence Context.

对于存储对象来说似乎也是如此，并且 Hibernate 严重依赖于 @Id 列。即使要使用自然标识符加载实体，它也会首先执行一个查询来获取实际的 @Id，然后进行第二个查询来获取实体本身(基于同一篇文章中的示例):

SELECT c.id AS id1_0_
FROM ChildrenObject c
WHERE c.code = 'child-code'

SELECT c.id AS id1_0_0_,
       c.code AS code2_0_0_,
       c.name AS name3_0_0_
FROM ChildrenObject c
WHERE c.id = 1