/**
  * @return string
  */
 public function getValidationRule()
 {
     $rule = parent::getValidationRule();
     return $rule . '|regex:/\\A[0-9]+\\z/';
 }
 /**
  * @return string
  */
 public function getValidationRule()
 {
     $rule = parent::getValidationRule();
     return $rule . '|regex:/\\A[0-9]+\\z/|exists:' . $this->getForeignTable() . ',id';
 }