Magento 通过 SOAP V2 API 计算总数，但促销规则不适用

我正在使用Magento Comunity Edition 1.7.0.2。我必须通过Magento SOAP V2 API计算总计，方法是通过传递行项目，运输方式，付款方式，地址和促销（优惠券代码）信息。我需要计算行项目总计（基本价格、税费、订单、行总计）和 Subtoatl、运费、折扣税和总计。我已经通过使用Mage的PHP脚本尝试过这个。我创建了一个报价对象，并在应用了运输购物车规则（使用优惠券/不带优惠券）的情况下获得了所需的所有计算。

但问题是，当我将该代码移动到Magento自定义SOAP Api模型方法时，它正在计算包括税在内的所有总计，但折扣不适用于它。我也尝试过结帐/购物车对象，但没有效果。我已经读过一些Magento API不启动Magento常规PHP会话的地方。可能是Magento会话无法通过API工作的情况吗？

以下是代码：

public function getTotals($data)
    {
            $shipping_method = $data->shipment_method;
            $payment_method =  $data->payment_method;
            $total_qty = 0;
            $quote = Mage::getModel('sales/quote'); 

            if($data->customer->email!="")
            {
                $customer_email = $data->customer->email;
                $customer = Mage::getModel("customer/customer");
                $customer->setWebsiteId(Mage::app()->getWebsite()->getId());
                $customer->loadByEmail($customer_email); //load customer by email id
                $quote->assignCustomer($customer);
            }

            foreach($data->lineitems as $p)
            {
                $product = Mage::getModel('catalog/product');
                $product->load($product->getIdBySku($p->SKU));
                $qty = $p->QTY;
                $buyInfo = array('qty' => $qty);
                $total_qty += $p->QTY;
                $quote->addProduct($product, new Varien_Object($buyInfo));
            }

                        $billingAddress = array(
            'firstname' => $data->billing_address->FirstName,
            'lastname' => $data->billing_address->LastName,
            'company' => $data->billing_address->CompanyName,
            'email' => $data->billing_address->Email,
            'street' => array(
            $data->billing_address->Address1,
            $data->billing_address->Address2
            ),
            'city' => $data->billing_address->City,
            'region_id' => $data->billing_address->FirstName,
            'region' => $data->billing_address->Region,
            'postcode' => $data->billing_address->PostalCode,
            'country_id' => $data->billing_address->CountryId,
            'telephone' => $data->billing_address->Telephone,
            'fax' => $data->billing_address->Fax,
            'customer_password' => '',
            'confirm_password' => '',
            'save_in_address_book' => '0',
            'use_for_shipping' => '0',
            );
            $shippingAddress = array(
            'firstname' => $data->shipping_address->FirstName,
            'lastname' => $data->shipping_address->LastName,
            'company' => $data->shipping_address->CompanyName,
            'email' => $data->shipping_address->Email,
            'street' => array(
            $data->shipping_address->Address1,
            $data->shipping_address->Address2
            ),
            'city' => $data->shipping_address->City,
            'region_id' => $data->shipping_address->RegionId,
            'region' => $data->shipping_address->Region,
            'postcode' => $data->shipping_address->PostalCode,
            'country_id' => $data->shipping_address->CountryId,
            'telephone' => $data->shipping_address->Telephone,
            'fax' => $data->shipping_address->Fax,
            'customer_password' => '',
            'confirm_password' => '',
            'save_in_address_book' => '0',
            'use_for_shipping' => '0',
            );

            $quote->getBillingAddress()
            ->addData($billingAddress);

                //$quote->setCouponCode($data->coupons[0]->coupanCode); 

            $quote->getShippingAddress()
            ->addData($shippingAddress)
            ->setShippingMethod($shipping_method)
            ->setPaymentMethod($payment_method);
            Mage::getSingleton('checkout/cart')
            ->setQuote($quote);

            Mage::getSingleton('checkout/cart')
            ->getQuote()
            ->getShippingAddress()
            ->setCollectShippingRates(true);
            Mage::getSingleton('checkout/cart')
            ->getQuote()
            ->setCouponCode(strlen($data->coupons[0]->coupanCode) ? $data->coupons[0]->coupanCode : '')
            ->collectTotals()
            ->save();
            $items = Mage::getSingleton('checkout/cart')->getItems();

当我尝试获得折扣并应用规则 ID 时，我什么也没得到:(

 $discount = $item->getDiscountAmount();
$apply_rule_id = $item->getAppliedRuleIds();