updating an entity in many-to-many relationship

Question

I have a Spring project that uses JPA with Hibernate and MySQL database. Database includes three tables: Users, Roles, and many-to-many join table UserRoles. Below are the corresponding classes for the tables.

ApplicationUser.java

@Entity
@Table(name = "APPLICATION_USER")
public class ApplicationUser extends ExtAuditInfo {

public static final Long SYSTEM_USERID = 1000L;


@Id
@Column(name = "APPLICATION_USER_ID")
private long applicationUserId;

@Column(name = "LOGIN_NAME")
private String loginName;

@Column(name = "LAST_NAME")
private String lastName;

@Column(name = "FIRST_NAME")
private String firstName;

@Column(name = "MIDDLE_NAME")
private String middleName;

@OneToMany(mappedBy = "id.applicationUser", cascade = CascadeType.ALL, fetch = FetchType.EAGER)
private List<UserRole> roles =new ArrayList<>();

//get and set methods

Role.java

@Entity
@Table(name = "ROLE")
@NamedQueries({
@NamedQuery(name = "Role.getRoleById", query = "select r from Role r where r.roleId =:roleId"))}
public class Role extends AuditInfo {

@Id
@Column(name="ROLE_ID")
private long roleId;

@Column(name="ACTIVE_FLAG")
private String activeFlag;

@Column(name="ROLE_NAME")
private String roleName;

@OneToMany(mappedBy = "id.role", fetch = FetchType.LAZY)
private List<UserRole> users = new ArrayList<>();

//get and set methods

UserRole.java

@Entity
@AssociationOverrides({
        @AssociationOverride(name = "id.applicationUser",
                joinColumns = @JoinColumn(name = "APPLICATION_USER_ID")),
        @AssociationOverride(name = "id.role",
                joinColumns = @JoinColumn(name = "ROLE_ID")) })
@Table(name = "USER_ROLE")
public class UserRole extends ExtAuditInfo implements Serializable{
    @EmbeddedId
    private UserRoleID id = new UserRoleID();

    @Column(name="USER_ROLE_VER")
    private long userRoleVer;

    public UserRole(){
    }

    @Transient
    public ApplicationUser getApplicationUser() {
        return this.id.getApplicationUser();
    }

    public void setApplicationUser(ApplicationUser applicationUser) {
        this.id.setApplicationUser(applicationUser);
    }

    public long getUserRoleVer() {
        return this.userRoleVer;
    }

    public void setUserRoleVer(long userRoleVer) {
        this.userRoleVer = userRoleVer;
    }

    @Transient
    public Role getRole() { return this.id.getRole(); }

    public void setRole(Role role) { this.id.setRole(role); }
}

UserRoleID.java

@Embeddable
public class UserRoleID implements Serializable {

    @ManyToOne(cascade = CascadeType.ALL)
    private ApplicationUser applicationUser;

    @ManyToOne(cascade = CascadeType.ALL)
    private Role role;

    private static final long serialVersionUID = 1L;

    public UserRoleID() {
    }

    public ApplicationUser getApplicationUser() {
        return this.applicationUser;
    }

    public void setApplicationUser(ApplicationUser applicationUser) {
        this.applicationUser = applicationUser;
    }

    public Role getRole() {
        return this.role;
    }

    public void setRole(Role role) {
        this.role = role;
    }
}

Now, when I create a sample user with viewer role, the record is being inserted into the Application_user and User_Role tables, but when I try to update the role of the user it is adding a new role to the user instead of updating the existing role.

This is what I'm doing

@TransactionAttribute(TransactionAttributeType.REQUIRED)
public void updateRole(ApplicationUser appUser, long roleId){
        EntityManager em=getEntityManager();
        TypedQuery<Role> query = em.createNamedQuery("Role.getRoleById", Role.class);
        query.setParameter("roleId",roleId);
        Role r = query.getSingleResult();
        UserRole userRole= appUser.getRole().get(0);
        userRole.setRole(r);
        em.merge(userRole);
        em.flush();
        em.detach(userRole);
}

Any idea, what to do to update the existing role instead of creating a new role in user_role table?

Answer 1

You are assigning new role to user, so a new record is added in user_role table, and old user_role entry is deleted. That's the right behavior. So it's not you called "update the role of user".

Update: You should delete role manually when many-to-many relationship.

appUser.getRoles().remove(userRole);
em.remove(userRole);
UserRole newUserRole = new UserRole();
newUserRole.setRole(r);
appUser.getRoles().add(newUserRole);