I am implementing many to many relationship between Users and Permissions and I cannot conclude where am I wrong, it is not working (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<>();
}

I implemented Users and Permissions with looking in this example, this is working (and I cannot see difference with Users and Permission):

@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);
    }
}

CodePudding user response：

rJPA uses (and creates in your case probably) intermediate join table for many to many relationship and you cannot use different reference column name from name you specified in entity.

So you need to set:

• in User class

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

• in Permission

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

• And same for other tables.