private function select_badge_type()
 {
     $age = age_from_birthdate(@$this->params["birthdate"]);
     if ($age && $age < MINOR_AGE) {
         $badge_type = BadgeType::default_minor();
     } else {
         $badge_type = BadgeType::default_adult();
     }
     $this->params["badge_type"] = $badge_type->db_name;
 }