Reply To: featured image from relationship field (backend)

• John Huebner

• November 27, 2023 at 11:20 am

If you can select multiple then ACF is returning an array. My code actually eliminates the return value so that doesn’t matter (forgot that), but we do have to deal with the possibility of an array return value. This will only work to get the first related post selected

add_action('acf/save_post', 'copy_image_from_relationship', 20);
function copy_image_from_relationship($post_id) {
  // check the post type
  if (get_post_type($post_id) != 'print-size') {
    // not the right post type
    return;
  }
  // get the post id for the related post
  $related_id = get_field('relationship_field_name', $post_id, false);
  if (is_array($related_id) && !empty($related_id)) {
    $related_id = $related_id[0];
  }
  if (!empty($related_id)) {
    // get the featured image ID from the related post
    $image_id = get_post_thumbnail_id($related_id);
    if ($image_id) {
      // set on current post being updated
      update_post_meta($post_id, '_thumbnail_id', $image_id);
    }
  }
}