I am trying to fetch the data from the database and update the post meta. Everything is perfect. I have even checked each variable. The method is also firing only once. The problem is that in the database I am still seeing the array but with blank values. a:6:{i:57;s:0:"";i:58;s:0:"";i:59;s:0:"";i:60;s:0:"";i:61;s:0:"";i:62;s:0:"";}

I really need a solution to why this update_post_meta is not working. I have even tried add_post_meta instead and it doesn’t work too.

function slug_save_post_callback($post_ID, $post, $update)
{
    if ($post->post_type != 'aps-products' || $post->post_status == 'auto-draft')
        return;
    if ($post->post_date_gmt != $post->post_modified_gmt)
        return;
    $result = getSpecs($post->post_title);
    $new_slug = sanitize_title($result[0] . ' ' . $result[1], $post_ID);
    if ($new_slug == $post->post_name)
        return; 
    // unhook this function to prevent infinite looping
    remove_action('save_post_aps-products', 'slug_save_post_callback', 100, 3);
    // update the post slug (WP handles unique post slug)
    wp_update_post(array(
        'ID' => $post_ID,
        'post_name' => $new_slug,
        'post_title' => $result[0] . ' ' . $result[1]
    ));
    // get aps attributes data from input fields
    $groups = get_aps_cat_groups(74);
    $groups_data = get_aps_groups_data();
    $attrs_data = get_aps_attributes_data();
    error_log("Executing");
    foreach ($groups as $groupId) {
        $group_data = $groups_data[$groupId];
        $group_values = get_aps_product_attributes($post->ID, $groupId);
        if ($group_data['attrs']) {
            if (aps_is_array($group_data['attrs'])) {
               // $frist = array();
                $value = '';
                foreach ($group_data['attrs'] as $attr_id) {
                    switch ($attr_id) {
                        case 2:
                            $value = "Smartphone";
                            break;
                        case 3:
                            $value = $result[1];
                            break;
                    }


                    $frist[$attr_id] = $value;
                }


                update_post_meta($post_ID, 'aps-attr-group-' . $groupId, $frist);

                $frist=[];
            }
        }
    }

    add_action('save_post_aps-products', 'slug_save_post_callback', 100, 3);
}
add_action('save_post_aps-products', 'slug_save_post_callback', 100, 3);