frontend\models\CreateOrderForm::getPreferentialItems PHP Method

    public function getPreferentialItems()
    {
        if ($this->_preferentialItems === null) {
            $this->_preferentialItems = [];
            $fee = Yii::$app->user->identity->getCartGoodsRealVolume($this->_store->id);
            if ($this->_store->has_down && $fee >= $this->_store->down_upper) {
                $this->_preferentialItems[Order::PREFERENTIAL_DOWN] = $this->_store->downMsg;
            }
            if ($this->_store->has_gift && $fee >= $this->_store->gift_upper) {
                $this->_preferentialItems[Order::PREFERENTIAL_GIFT] = $this->_store->giftMsg;
            }
            if (!empty($this->_preferentialItems)) {
                $this->_preferentialItems[Order::PREFERENTIAL_NONE] = '不使用优惠';
            }
        }
        return $this->_preferentialItems;
    }