public function getNotEmptyMessage($field)
    {
        if (!isset($this->_fields[$field])) {
            return null;
        }

        $defaultMessage = 'This field cannot be left empty';
        if ($this->_useI18n) {
            $defaultMessage = __d('cake', 'This field cannot be left empty');
        }

        $notBlankMessage = null;
        foreach ($this->_fields[$field] as $rule) {
            if ($rule->get('rule') === 'notBlank' && $rule->get('message')) {
                return $rule->get('message');
            }
        }

        return isset($this->_allowEmptyMessages[$field])
            ? $this->_allowEmptyMessages[$field]
            : $defaultMessage;
    }