Add image to product gallery programmatically - woocommerce .Woocommerce manage field ‘_product_image_gallery’ with id of images separatly for comma.

Add image to product gallery programmatically - woocommerce

/*

  Add image to product gallery programmatically - woocommerce
  Woocommerce manage field ‘_product_image_gallery’ with id of images separatly for comma.

*/

$list_id = "444,555";
update_post_meta($post_id,'_product_image_gallery',$list_id);

I have a similar set up but only one attachment ID gets placed in the product image gallery.
Heres what I got:

$commaList = "2104,2105,2106,";
update_post_meta( $post_id, '_product_image_gallery', $commaList);

Are you sure this works to add images to the product gallery programmatically?

Works for me:
$media = get_attached_media('image', $pid);
update_post_meta($pid, '_product_image_gallery', implode(',', array_keys($media)));