Woocommerce可变产品下拉列表

我正在尝试为我的woocommerce商店实施数量下拉,我发现下面的代码启用单个产品,但我不能让它适用于有变化的产品.

 "cart[{$cart_item_key}][qty]",
  'input_value' => $cart_item['quantity'],
  'max_value'   => $_product->backorders_allowed() ? '' : $_product->get_stock_quantity(),
  'min_value'   => '0'
), $_product, false );
*/
function woocommerce_quantity_input($data) {
    global $product;
  $defaults = array(
    'input_name'    => $data['input_name'],
    'input_value'   => $data['input_value'],
    'max_value'   => apply_filters( 'woocommerce_quantity_input_max', '', $product ),
    'min_value'   => apply_filters( 'woocommerce_quantity_input_min', '', $product ),
    'step'    => apply_filters( 'woocommerce_quantity_input_step', '1', $product ),
    'style'   => apply_filters( 'woocommerce_quantity_style', 'float:left; margin-right:10px;', $product )
  );
  if ( ! empty( $defaults['min_value'] ) )
    $min = $defaults['min_value'];
  else $min = 1;
  if ( ! empty( $defaults['max_value'] ) )
    $max = $defaults['max_value'];
  else $max = 20;
  if ( ! empty( $defaults['step'] ) )
    $step = $defaults['step'];
  else $step = 1;
  $options = '';
  for ( $count = $min; $count <= $max; $count = $count+$step ) {
    $selected = $count === $defaults['input_value'] ? ' selected' : '';
    $options .= '' . $count . '';
  }
  echo '
' . $options . '
';
}
?>

我追求的结果如下图所示

这可能与woocommerce？