Java：Hibernate @OneToOne映射 [英] Java: Hibernate @OneToOne mapping

问题描述

假设我有一个名为<$ c的表$ c> status 看起来像这样：

  + --------- --------------------------------------- + 
 |状态| 
 + --------------------------------------------- --- + 
 | id | frn_user_id | frn_content_id |状态| 
 + ---- + ------------- + ---------------- + --------- --- + 
 | 1 | 111 | 0 | 主动| 
 + ---- + ------------- + ---------------- + --------- --- + 
 | 2 | 0 | 222 | 无效| 
 + ---- + ------------- + ---------------- + --------- --- + 
  

我有一个用于 User 看起来像这样：



  @Entity 
 @Table（name =user）
 public class User 
 @Id 
 @GeneratedValue（strategy = GenerationType.AUTO）
 @Column（name =id，nullable = false）
 private Integer id ; 
 
 @OneToOne（cascade = CascadeType.ALL，fetch = FetchType.EAGER，mappedBy =userId）
私人状态状态; 
 
 // getters and setters 
} 
  

一个用于 Content ，另一个用于 Status 的实体，如下所示：

  @Entity 
 @Table（name =status）
 public class Status {
 @Id 
 @GeneratedValue strategy = GenerationType.AUTO）
 @Column（name =id，nullable = false）
 private Integer id; 
 
 @Column（name =frn_user_id）
 private Integer userId; 
 
 @Column（name =frn_content_id）
 private Integer contentId; 
 
 @Column（name =status）
私人字符串状态; 
 
 // getters and setters 
} 
  

当我执行阅读 User ，我期望 User.getStatus（）将返回一个 Status 具有 id = 1 的对象。相反，我得到一个AnnotationException：引用的属性不是（One | Many）ToOne：Status.userId在mappedBy User.status中

教程和示例，但是我迄今为止尝试过的所有内容都失败了。

另外值得注意的是：这应该支持一对一或者一对一关系，因为某些用户和内容记录不会在状态中引用 code> table。

任何帮助将不胜感激！

您的状态实体不得具有Integer类型的属性 userId 和 contentId ，其映射为 @Column 。它必须具有User和Content类型的属性 user 和 content ，映射到 @OneToOne ：

  public class User {
 @OneToOne（mappedBy =user）
私人状态状态; 
 // ... 
} 
 
公共班级状态{
 @OneToOne 
 @JoinColumn（name =frn_user_id）
 private用户用户; 
 // ... 
} 
  

用户有一个状态。状态有一个用户。

I'm trying to get Hibernate @OneToOne annotations working and not having much success here...

Let's say I've got a table called status that looks like this:

+------------------------------------------------+
|                     status                     |
+------------------------------------------------+
| id | frn_user_id | frn_content_id |   status   |
+----+-------------+----------------+------------+
|  1 |     111     |        0       |  "active"  |
+----+-------------+----------------+------------+
|  2 |      0      |       222      | "inactive" |
+----+-------------+----------------+------------+

And I've got an entity for User that looks like this:

@Entity
@Table(name = "user")
public class User {
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name = "id", nullable = false)
    private Integer id;

    @OneToOne(cascade = CascadeType.ALL, fetch = FetchType.EAGER, mappedBy = "userId")
    private Status status;

    // getters and setters
}

And a similar one for Content, and another entity for Status that looks like this:

@Entity
@Table(name = "status")
public class Status {
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @Column(name = "id", nullable = false)
    private Integer id;

    @Column(name = "frn_user_id")
    private Integer userId;

    @Column(name = "frn_content_id")
    private Integer contentId;

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

    // getters and setters
}

When I perform a read on User, I expect that User.getStatus() will return a Status object with id=1. Instead, I get an AnnotationException: "Referenced property not a (One|Many)ToOne: Status.userId in mappedBy User.status"

I've poured through docs, tutorials and examples here on SO, but everything I've tried so far has failed.

Also worth noting: This should support a one-to-zero-or-one relationship, as some user and content records will not have a reference in the status table.

Any help would be greatly appreciated!

解决方案

Your Status entity must not have properties userId and contentId of type Integer, mapped with @Column. It must have properties user and content of type User and Content, mapped with @OneToOne:

public class User {
    @OneToOne(mappedBy = "user")
    private Status status;
    // ...
}

public class Status {
    @OneToOne
    @JoinColumn(name = "frn_user_id")
    private User user;
    // ...
}

A user has one status. A status has one user.

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