Количество купленных товаров

$oXmlCart = Core::factory('Core_Xml_Entity')->name('cart');

$aCart_Items = Shop_Cart_Controller::instance()->getAll($Shop_Controller_Show->getEntity());
foreach ($aCart_Items as $oCart_Item) {
   $oXmlCart->addEntity(
      Core::factory('Core_Xml_Entity')
         ->name('item')
         ->addAttribute('id', $oCart_Item->shop_item_id)
         ->addAttribute('quantity', $oCart_Item->quantity)
   );
}

$Shop_Controller_Show
   ->addEntity($oXmlCart)
   ->xsl(Core_Entity::factory('Xsl')->getByName($xslTemplate))
   ->show();

   <xsl:template match="shop_item">
      <div class="product-group__item">
         <xsl:value-of select="name"/>
      </div>
      <xsl:variable name="shop_item_id" select="@id"/>
      <xsl:choose>
         <xsl:when test="count(/shop/cart/item[@id = $shop_item_id])">
            <h1>
               <xsl:text>В корзине уже</xsl:text>
               <xsl:value-of select="/shop/cart/item[@id = $shop_item_id]/@quantity"/>
            </h1>
         </xsl:when>
         <xsl:otherwise>
            <h4>Положить в корзину</h4>
         </xsl:otherwise>
      </xsl:choose>
   </xsl:template>