/**
  * get product variety list
  */
 function getProductVarietyList($product_id)
 {
     if (!is_numeric($product_id)) {
         return false;
     }
     require_once 'models/ecommerce/ecommerce_product_variety.php';
     $ProductVariety = new ecommerce_product_variety();
     $varieties = $ProductVariety->listing("product_id = {$product_id}", 'priority DESC, id ASC');
     if (is_array($varieties)) {
         foreach ($varieties as $kv => $v) {
             $variety[$kv] = $ProductVariety->getVarietyDetail($v['id']);
         }
         return $variety;
     } else {
         msg("Product id {$product_id} has no varieties", 'error', 1);
         return false;
     }
 }