Spring Boot / Hibernate：如何定義一對一的單向關系

Question

我有具有name和parent People實體，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
}

當我使用PUT存儲數據時，我將id 1指定為路徑變量，並提供name作為數據輸入，並且沒有像下面那樣傳遞parent ：

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

響應

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

當我檢索存儲的內容時，盡管我在發出curl請求時傳遞了null ，但parent已經具有指向對象本身的鏈接。

休眠One-to-One關系在做什么？

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)

通過閱讀您的代碼，我認為您需要@JoinColumn 。

請參見Hibernate自引用一對一關系-映射/擁有的一面