Magento – Best practice to connect Magento 2 to price/product service

I've done this for importing group prices with SOAPv2 for Magento CE 1.7.0.2 some time ago and wrote a a (german) blogpost about this (Google translate might help). I added the important parts with an english explanation here and hope this helps you getting started.

Basically you need to rewrite the catalog/product_api_v2 model and extend the _prepareDataForSave method.

Create a new module

In my example it's Avoe_Catalog:

In Avoe/Catalog/etc/config.xml rewrite the Product API:

<config>
    <modules>
        <Avoe_Catalog>
            <version>0.0.1</version>
        </Avoe_Catalog>
    </modules>
    <global>
        <models>
            <avoecatalog>
                <class>Avoe_Catalog_Model</class>
            </avoecatalog>

            <catalog>
                <rewrite>
                    <product_api_v2>Avoe_Catalog_Model_Product_Api_V2</product_api_v2>
                </rewrite>
            </catalog>
        </models>
    </global>
</config>

Avoe/Catalog/Model/Product/Api/V2.php:

copy the _prepareDataForSave method from Mage_Catalog_Model_Product_Api_V2 to your new Api model:

class Avoe_Catalog_Model_Product_Api_V2 extends Mage_Catalog_Model_Product_Api_V2 {

   protected function _prepareDataForSave ($product, $productData) {

      ...

     if (property_exists($productData, 'tier_price')) {
     ...
     }

     //add the following code

     if (property_exists($productData, 'group_price')) {
         $groupPrices = Mage::getModel('avoecatalog/product_attribute_groupprice_api_V2')
             ->prepareGroupPrices($product, $productData->group_price);
         $product->setData("group_price", $groupPrices);
     }

   }

}

Create the following file:

Avoe/Catalog/Model/Product/Attribute/Groupprice/Api/V2.php copied from Mage/Catalog/Model/Product/Attribute/Tierprice/Api/V2.php:

In this copied file, I've replaced all $tierPrices with $groupPrices and updated checks with needed options (cust_group, price, website_id).

class Avoe_Catalog_Model_Product_Attribute_Groupprice_Api_V2 extends Mage_Catalog_Model_Api_Resource
{
    /**
     *  Prepare group prices for save
     *
     *  @param      Mage_Catalog_Model_Product $product
     *  @param      array $groupPrices
     *  @return     array
     */
    public function prepareGroupPrices($product, $groupPrices = null)
    {
        if (!is_array($groupPrices)) {
            return null;
        }

        $updateValue = array();

        foreach ($groupPrices as $groupPrice1) {
            $groupPrice = unserialize($groupPrice1);

            if (!is_array($groupPrice)
                || !isset($groupPrice["cust_group"])
                || !isset($groupPrice["price"])) {
                $this->_fault('data_invalid', Mage::helper('catalog')->__('Invalid Group Prices'));
            }

            if (!isset($groupPrice["website_id"]) || $groupPrice["website_id"] == 'all') {
                $groupPrice["website_id"] = 0;
            } else {
                try {
                    $groupPrice["website_id"] = Mage::app()->getWebsite($groupPrice["website"])->getId();
                } catch (Mage_Core_Exception $e) {
                    $groupPrice["website_id"] = 0;
                }
            }

            if (intval($groupPrice["website_id"]) > 0 && !in_array($groupPrice["website_id"], $product->getWebsiteIds())) {
                $this->_fault('data_invalid', Mage::helper('catalog')->__('Invalid group prices. The product is not associated to the requested website.'));
            }

            if (!isset($groupPrice["cust_group"])) {
                $groupPrice["cust_group"] = '0';
            }

            if ($groupPrice["cust_group"] == 'all') {
                $groupPrice["cust_group"] = '0';
            }

            $updateValue[] = array(
                'website_id' => $groupPrice["website_id"],
                'cust_group' => $groupPrice["cust_group"],
                'price'      => $groupPrice["price"],
                'delete'     => $groupPrice["delete"] 
            );

        }

        return $updateValue;
    }
}

SOAPv2 API call

You can insert group prices via SOAPv2 then the following way:

$newProductData = new stdClass();
$additionalAttrs = array();

$gp = array(
    "0" => array (
            "website_id" => "0",
            "cust_group" => "1",
            "price" => "11.11",
            "delete" => "1"
        ),
    "1" => array (
            "website_id" => "0",
            "cust_group" => "0",
            "price" => "12.12"
        )
    );

$gp = array("key" => "group_price", "value" => array(serialize($gp[0]),serialize($gp[1])));

$additionalAttrs['multi_data'][] = $gp;
$newProductData->additional_attributes = $additionalAttrs;

$result = $client->catalogProductUpdate($sessionId,$prodSku,$newProductData,"","sku");

I doubt it's not getting called in config or bundle item. Please try this code in your observer.php.

<?php
class Ucs_CatalogOrder_Model_Observer
{
    public function checkoutCartProductAddAfter($observer) {
    $item = $observer->getEvent()->getQuoteItem();
    if ($item->getParentItem()) {
       $item = $item->getParentItem();
    }
    $walletAmount = Mage::app()->getRequest()->getPost('card_wallet_amount');

    //not sure why calling $item->getOriginalPrice() not getting product's price
    //getting price from catalog model
    $productPrice = Mage::getModel('catalog/product')->load($item->getProductId())->getFinalPrice();

    //adding custom with original price
    $finalPrice = (int)$walletAmount + (int)$productPrice;

    if($finalPrice > 0){
        $item->setCustomPrice($finalPrice);
        $item->setOriginalCustomPrice($finalPrice);
        $item->setCardWalletAmount($finalPrice);
        $item->getProduct()->setIsSuperMode(true);
    }
        //Mage::getSingleton('core/session')->addSuccess($finalPrice); 

}