protected function validateCouponCheckout()
    {
        $price_rule_id = $this->getPosted('check_pricerule', null, true, 'integer');

        if (empty($price_rule_id)) {
            return null;
        }

        $code = $this->getSubmitted('data.pricerule_code', '');

        if ($code === '') {
            return null;
        }

        if (!$this->order->priceRuleCodeMatches($price_rule_id, $code)) {
            $this->setError('pricerule_code', $this->text('Invalid code'));
            $this->setMessageFormCheckout('components.danger', $this->text('Invalid code'));
        }
    }