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spring - 两个实体之间的共享主键不起作用

问题描述

我创建了两个实体，即 Teacher 和 Detail，代码片段如下所示

教师.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
}

细节.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，只有教师表正在更新值

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();
}

执行后只用指定的值更新教师表。详细表仍显示为空

标签： springhibernatejpaormhibernate-mapping

解决方案

它不完全那样工作。您仍然需要 id 字段Detail，因此添加：

@Id
private long id;

到你的Deatail班级。

并且 - 正如评论所建议的那样 - 将@Id字段中的注释替换Teacher为@MapsId. 这样，只有当您还将教师设置为详细信息时，Teacher才会将 id 映射到 id Detail- 您始终需要设置关系的双方 - 例如：

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

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