vadimf, примерно можно так:
if ($Shop_Controller_Show->group)
{
$oShopGroup = Core_Entity::factory('Shop_Group', $Shop_Controller_Show->group);
$oShopItems = $oShopGroup->Shop_Items;
$oShopItems
->queryBuilder()
->where('image_large', '!=', '')
->where('image_small', '!=', '')
->limit(1);
$aShopItems = $oShopItems->findAll(FALSE);
$Shop_Controller_Show->addEntity(
Core::factory('Core_Xml_Entity')
->name('shop_item_image')->value($aShopItems)
);
}