ManyToMany的應用-Spring不起作用

我正在實作用戶和權限之間的多對多關系，但我無法斷定我錯在哪里，它不起作用（Unable to map collection rs.raf.demo.model.User.permissions）：

@Data
@Entity
public class User {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "user_id")
    private Long userId;

    @Column
    private String username;

    @Column
    private String password;

    @ManyToMany
    @JoinTable(
            name = "USERS_PERMISSIONS",
            joinColumns = @JoinColumn(name = "USER_ID", referencedColumnName = "ID"),
            inverseJoinColumns = @JoinColumn(name = "PERMISSION_ID", referencedColumnName = "ID")
    )
    private List<Permission> permissions = new ArrayList<>();
}

================================================== ================================

@Data
@Entity
public class Permission {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "permission_id")
    private Long userId;

    private String type;

    @ManyToMany
    @JoinTable(
            name = "USERS_PERMISSIONS",
            joinColumns = @JoinColumn(name = "PERMISSION_ID", referencedColumnName = "ID"),
            inverseJoinColumns = @JoinColumn(name = "USER_ID", referencedColumnName = "ID")
    )
    @JsonIgnore
    private List<User> users = new ArrayList<>();
}

我在這個例子中實作了用戶和權限，這是有效的（我看不出用戶和權限的區別）：

@Data
@Entity
@Table(name = "STUD")
public class Student {

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    private String lastName;

    private String firstName;

    @ManyToMany
    @JoinTable(
            name = "STUDENTS_COURSES",
            joinColumns = @JoinColumn(name = "STUDENT_ID", referencedColumnName = "ID"),
            inverseJoinColumns = @JoinColumn(name = "COURSE_ID", referencedColumnName = "ID")
    )
    private List<Course> courses = new ArrayList<>();
}

================================================== ==============================

@Data
@Entity
public class Course {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;

    private String title;

    @ManyToMany
    @JoinTable(
            name = "STUDENTS_COURSES",
            joinColumns = @JoinColumn(name = "COURSE_ID", referencedColumnName = "ID"),
            inverseJoinColumns = @JoinColumn(name = "STUDENT_ID", referencedColumnName = "ID")
    )
    @JsonIgnore
    private List<Student> students = new ArrayList<>();

    public void addStudent(Student student) {
        students.add(student);
        student.getCourses().add(this);
    }

    public void removeStudent(Student student) {
        students.remove(student);
        student.getCourses().remove(this);
    }
}

uj5u.com熱心網友回復：

rJPA 為多對多關系使用（并可能在您的情況下創建）中間連接表，并且您不能使用與您在物體中指定的名稱不同的參考列名稱。

所以你需要設定：

• 在用戶類

@ManyToMany
    @JoinTable(
            name = "USERS_PERMISSIONS",
            joinColumns = @JoinColumn(name = "USER_ID", referencedColumnName = "USER_ID"),
            inverseJoinColumns = @JoinColumn(name = "PERMISSION_ID", referencedColumnName = "PERMISSION_ID")
    )

• 在許可

@ManyToMany
    @JoinTable(
            name = "USERS_PERMISSIONS",
            joinColumns = @JoinColumn(name = "PERMISSION_ID", referencedColumnName = "PERMISSION_ID"),
            inverseJoinColumns = @JoinColumn(name = "USER_ID", referencedColumnName = "USER_ID")
    )

• 其他表也一樣。

標籤：春天 数据库 弹簧数据 多对多

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