Magento 1.9 – API SOAP V2 CatalogProductList WSDL Issues

I want to get a list of all products using magento API V2 SOAP catalogProductList endpoint, but I want to add the following fields to every product in response xml: price, quantity and manage_stock.

In order to do this, I made following changes:

In file: app\code\core\Mage\Catalog\etc\wsdl.xml, I added

<element name="price" type="xsd:string"/>
<element name="qty" type="xsd:string"/>
<element name="manage_stock" type="xsd:string"/> 

to <complexType name="catalogProductEntity"> so the tag looks like this:

<complexType name="catalogProductEntity">
    <all>
        <element name="product_id" type="xsd:string"/>
        <element name="sku" type="xsd:string"/>
        <element name="name" type="xsd:string"/>
        <element name="set" type="xsd:string"/>
        <element name="type" type="xsd:string"/>
        <element name="category_ids" type="typens:ArrayOfString"/>
        <element name="website_ids" type="typens:ArrayOfString"/>
        <element name="price" type="xsd:string"/>
        <element name="qty" type="xsd:string"/>
        <element name="manage_stock" type="xsd:string"/>
    </all>
</complexType>

Same changes have been made to wsi.xml( added xsd:element tag).

In file app\code\core\Mage\Catalog\Model\Product\Api.php, in method items, I made following changes:

public function items( $filters = null, $store = null ) {
        $collection = Mage::getModel( 'catalog/product' )->getCollection()
                          ->addStoreFilter( $this->_getStoreId( $store ) )
                          ->addAttributeToSelect( 'name' )
                          ->addAttributeToSelect( 'price' )
                          ->joinField( 'qty', 'cataloginventory/stock_item', 'qty', 'product_id=entity_id', '{{table}}.stock_id=1', 'left' )
                          ->joinField( 'manage_stock', 'cataloginventory/stock_item', 'manage_stock', 'product_id=entity_id', null, 'left');

        /** @var $apiHelper Mage_Api_Helper_Data */
        $apiHelper = Mage::helper( 'api' );
        $filters   = $apiHelper->parseFilters( $filters, $this->_filtersMap );
        try {
            foreach ( $filters as $field => $value ) {
                $collection->addFieldToFilter( $field, $value );
            }
        }
        catch ( Mage_Core_Exception $e ) {
            $this->_fault( 'filters_invalid', $e->getMessage() );
        }
        $result = array ();
        foreach ( $collection as $product ) {//added price, qty, manage_stock to result
            $result[] = array (
                'product_id'   => $product->getId(),
                'sku'          => $product->getSku(),
                'name'         => $product->getName(),
                'set'          => $product->getAttributeSetId(),
                'type'         => $product->getTypeId(),
                'category_ids' => $product->getCategoryIds(),
                'website_ids'  => $product->getWebsiteIds(),
                'price'        => $product->getPrice(),
                'qty'          => $product->getQty(),
                'manage_stock' => $product->getManageStock()
            );
        }

        return $result;
}

When I make the soap request, I do not receive those 3 parameters, I only receive product_id, sku, name, set, type, category_ids and website_ids, even though I receive the correct wsdl configuration.

Here is an item returned by API after above changes were mage:

<item xsi:type="ns1:catalogProductEntity">
<product_id xsi:type="xsd:string">1</product_id>
    <sku xsi:type="xsd:string">2435</sku>
    <name xsi:type="xsd:string">product</name>
    <set xsi:type="xsd:string">4</set>
    <type xsi:type="xsd:string">simple</type>
    <category_ids SOAP-ENC:arrayType="xsd:string[4]" xsi:type="ns1:ArrayOfString">
        <item xsi:type="xsd:string">2</item>
        <item xsi:type="xsd:string">3</item>
        <item xsi:type="xsd:string">4</item>
        <item xsi:type="xsd:string">5</item>
    </category_ids>
    <website_ids SOAP-ENC:arrayType="xsd:string[1]" xsi:type="ns1:ArrayOfString">
        <item xsi:type="xsd:string">1</item>
    </website_ids>
</item>

I cleared cache, made sure Api.php file is not overriden. Could you tell me what am I doing wrong?

Thanks!