Question

我创建了两个实体，即Teacher和Detail，代码片段如下所示

Teacher.java

@Entity
@Table(name = "teacher")
public class Teacher implements Serializable {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "id")
    private long id;
    @Column(name = "name")
    private String name;
    @Column(name = "age")
    private int age;

    @OneToOne(mappedBy = "teacher", cascade = CascadeType.ALL)
    private Detail detail;

    public Teacher() {
    }

    public Teacher(String name, int age) {
        this.name = name;
        this.age = age;
    }
//getter and setter
}

Detail.java

@Entity
@Table(name = "detail")
public class Detail implements Serializable {

    @Id
    @OneToOne(cascade = CascadeType.ALL)
    @JoinColumn(name = "id")
    private Teacher teacher;
    @Column(name = "subjects")
    private String subjects;

    public Detail() {
    }

    public Detail(String subjects) {
        this.subjects = subjects;
    }
//getter and setter
}

我正在尝试使用共享主键概念实现一对一映射但是当我执行控制器时，只有“教师”表正在使用该值更新

try {
    Teacher teacher=new Teacher("xyz",23);
    Detail detail=new Detail("Java,c,c++");

    teacher.setDetail(detail);
    session.beginTransaction();
    session.save(teacher);
    session.getTransaction().commit();
    model.addAttribute("added", "data inserted");
    session.close();
}

执行后仅使用指定值更新教师表。详细信息表仍显示为空

Answer 1

它不能完全那样工作。您仍然需要Detail中的id字段，因此添加：

@Id
private long id;

进入您的Deatail班。

并且-如注释所建议-将字段@Id中的Teacher注释替换为@MapsId。这样，Teacher的ID会映射到Detail的ID，但只有在您还将教师设置为详细信息的情况下-始终需要设置关系的两面，例如：

teacher.setDetail(detail);
detail.setTeacher(teacher);

两个实体之间共享的主键不起作用

1 个答案: