@OneToOne映射洗掉然后插入而不是更新-有解無憂

我寫了一些內部有一對一關系的 spring boot 物體。例如：

Student 物體

@OneToOne(cascade = CascadeType.ALL, orphanRemoval = true, fetch = FetchType.LAZY, mappedBy = "student")
private StudentClub studenttClub;

StudentClub 物體

@OneToOne(cascade = CascadeType.ALL, fetch = FetchType.LAZY)
@JoinColumn(name = "student_id", insertable = false, updatable = false)
private Student student;

當我嘗試更新一些學生社團資訊（即club_code）使用.save的的Student存盤庫，它洗掉然后插入更新的資料。

休眠：從 student_club 中洗掉 club_code=? 和 student_id=?

Hibernate：插入 student_club (club_code, student_id) 值 (?,?)

我們可以只用 1 條陳述句來完成，例如

休眠：更新...

uj5u.com熱心網友回復：

.saveOrUpdate() 方法你可以使用它

- 根據識別符號存在與否呼叫 save() 或 update() 。例如，如果識別符號存在，則將呼叫 update()，否則將呼叫 save()。

uj5u.com熱心網友回復：

在 StudentClub 物體上移動 @JoinColumn

@Entity
@Table(name = "STUDENT")
public class StudentEntity {
    @Id
    @SequenceGenerator(name = "StudentGen", sequenceName = "STUDENT_SEQ", allocationSize = 1)
    @GeneratedValue(generator = "StudentGen", strategy = GenerationType.SEQUENCE)
    @Column(name = "ID", unique = true)
    protected Long id;

    @OneToOne(fetch = FetchType.LAZY, cascade = {CascadeType.PERSIST, CascadeType.MERGE, CascadeType.REMOVE})
    @JoinColumn(name = "CLUB")
    public StudentClubEntity club;
}


@Entity
@Table(name = "STUDENT_CLUB")
public class StudentClubEntity {
    @Id
    @SequenceGenerator(name = "StudentClubGen", sequenceName = "STUDENT_CLUB_SEQ", allocationSize = 1)
    @GeneratedValue(generator = "StudentClubGen", strategy = GenerationType.SEQUENCE)
    @Column(name = "ID", unique = true)
    protected Long id;


    @Column(name = "NAME")
    public String name = "";

    @OneToOne(fetch = FetchType.LAZY)
    public StudentEntity student;
}

嘗試測驗...

@Test
public void test() {
    System.out.println("test");

    StudentEntity student = new StudentEntity();
    StudentClubEntity club = new StudentClubEntity();

    student.club = club;

    System.out.println("*****************************");
    student = studentRepository.saveAndFlush(student);

    student.club.name = "NEW NAME";
    student = studentRepository.saveAndFlush(student);

    System.out.println("*****************************");
}

結果

*****************************
Hibernate: call next value for student_seq
Hibernate: call next value for student_club_seq
Hibernate: insert into student_club (name, student_id, id) values (?, ?, ?)
Hibernate: insert into student (club, id) values (?, ?)
Hibernate: update student_club set name=?, student_id=? where id=?
*****************************

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