Spring Boot / Hibernate：如何定义一对一的单向关系

Question

我有具有name和parent People实体，其中parent是People 。

@Entity
public class People {

    @Id
    private Long id;

    @Column
    @NotNull(message = "error.name.type.null")
    private String name;

    @OneToOne(cascade=CascadeType.ALL,fetch = FetchType.EAGER)
    private People parent;

    // getters and setters
}

当我使用PUT存储数据时，我将id 1指定为路径变量，并提供name作为数据输入，并且没有像下面那样传递parent ：

curl -i -X PUT -H "Content-Type:application/json" -d '{"name":"John"}'

响应

http://localhost:8080/people/1
HTTP/1.1 200 
Content-Type: application/json;charset=UTF-8
Transfer-Encoding: chunked
Date: Wed, 12 Oct 2016 13:51:52 GMT

当我检索存储的内容时，尽管我在发出curl请求时传递了null ，但parent已经具有指向对象本身的链接。

休眠One-to-One关系在做什么？

curl -i -X GET http://localhost:8080/people
HTTP/1.1 200 
Content-Type: application/hal+json;charset=UTF-8
Transfer-Encoding: chunked
Date: Wed, 12 Oct 2016 13:53:10 GMT

{
  "_embedded" : {
    "people" : [ {
      "name" : "John",
      "_links" : {
        "self" : {
          "href" : "http://localhost:8080/people/1"
        },
        "people" : {
          "href" : "http://localhost:8080/people/1"
        },
        "parent" : {
          "href" : "http://localhost:8080/people/1/parent"
        }
      }
    } ]
  },
  "_links" : {
    "self" : {
      "href" : "http://localhost:8080/people"
    },
    "profile" : {
      "href" : "http://localhost:8080/profile/people"
    },
    "search" : {
      "href" : "http://localhost:8080/people/search"
    }
  }
}

Answer 1

您缺少@JoinColumn(name="parent_id")或@OneToOne(mappedBy="id", cascade=CascadeType.ALL,fetch = FetchType.EAGER)

通过阅读您的代码，我认为您需要@JoinColumn 。

请参见Hibernate自引用一对一关系-映射/拥有的一面