Hibernate一對一單向將null放入外鍵

我在兩個表之間有一對一的映射：

人-> 身份證| 姓名

person_status -> id | 人名 | 地位

我需要一個單向映射，即我想從 person 物件中獲取 personStatus，但不是相反。

以下是物體：

@Entity(name = "Person")
class PersonEntity(
    @Id
    @Column(name = "id", updatable = false, nullable = false)
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    var id: Long? = null,

    val name: String,

    @OneToOne(mappedBy = "person", cascade = [CascadeType.ALL])
    var personStatus: PersonStatusEntity,
)

@Entity(name = "PersonStatus")
class PersonStatusEntity(
    @Id
    @Column(name = "id", updatable = false, nullable = false)
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    var id: Long? = null,

    @OneToOne(cascade = [CascadeType.ALL])
    @JoinColumn(name = "person_id", referencedColumnName = "id")
    var person: PersonEntity? = null,

    @Enumerated(EnumType.STRING)
    val status: Status,

    @UpdateTimestamp
    val updateTime: OffsetDateTime? = null
)

現在，當我運行時personRepository.findOneByName("John")，我得到了 PersonEntity 物件，其中填充了 personStatus 欄位。但是在那個 personStatus 物件中，這個 person 物件是空的。

personEntity = 
-- id = 1
-- name = "John"
-- personStatus = 
----- id = 1
----- person = null
----- status = APPROVED
----- updateTime = "2022-10-14T10:50:21.519228 11:00"

理想情況下，personStatus 中的這個 person 欄位不應該存在，因為我不想從 personStatus 物件訪問一個人。但是我無法找出正確的注釋來告訴休眠在加入時要查找的列。如果沒有辦法做到這一點，那么至少它不應該為空。我查看了一些現有的問題，但他們正在做雙向映射，我試圖避免這種情況。我怎樣才能做到這一點？謝謝。

uj5u.com熱心網友回復：

為什么需要單獨的主鍵PersonStatus？改為這樣建模：

@Entity(name = "Person")
class PersonEntity(
    @Id
    @Column(name = "id", updatable = false, nullable = false)
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    var id: Long? = null,

    val name: String,

    @OneToOne(cascade = [CascadeType.ALL], orphanRemoval = true)
    @JoinColumn(name = "id", referenceColumnName = "person_id")
    var personStatus: PersonStatusEntity,
)
@Entity(name = "PersonStatus")
class PersonStatusEntity(
    @Enumerated(EnumType.STRING)
    val status: Status,

    @UpdateTimestamp
    val updateTime: OffsetDateTime? = null
)

甚至更好，通過輔助表：

@Entity(name = "Person")
@SecondaryTable(name = "PersonStatus", pkJoinColumns = @PrimaryKeyJoinColumn(name = "person_id"))
class PersonEntity(
    @Id
    @Column(name = "id", updatable = false, nullable = false)
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    var id: Long? = null,

    val name: String,

    @Embedded
    var personStatus: PersonStatus,
)
@Embeddable
class PersonStatusEntity(
    @Column(table = "PersonStatus")
    @Enumerated(EnumType.STRING)
    val status: Status,

    @Column(table = "PersonStatus")
    @UpdateTimestamp
    val updateTime: OffsetDateTime? = null
)

也許你需要行內這個：

@Entity(name = "Person")
@SecondaryTable(name = "PersonStatus", pkJoinColumns = @PrimaryKeyJoinColumn(name = "person_id"))
class PersonEntity(
    @Id
    @Column(name = "id", updatable = false, nullable = false)
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    var id: Long? = null,

    val name: String,

    @Column(table = "PersonStatus")
    @Enumerated(EnumType.STRING)
    val status: Status,

    @Column(table = "PersonStatus")
    @UpdateTimestamp
    val updateTime: OffsetDateTime? = null
)

標籤：爪哇休眠科特林弹簧数据-jpa休眠映射

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