I am trying to automatically add a video thumbnail from Vimeo or YouTube as the featured image when a new custom post type video is add/updated. The video ID is an advanced custom field. Here's my non-working code:

 * Gets a vimeo thumbnail url
 * @param mixed $id A vimeo id (ie. 1185346)
 * @return thumbnail's url
function getVimeoThumb($id) {
    $data = file_get_contents("http://vimeo.com/api/v2/video/".$id.".json");
    $data = json_decode($data);
    return $data[0]->thumbnail_large;

 * Gets a youtube thumbnail url
 * @param mixed $id A youtube id
 * @return thumbnail's url
function getYoutubeThumb($id) {
    $data = file_get_contents("https://www.googleapis.com/youtube/v3/videos?key=AIzaSy...&part=snippet&id=".$id);
    $data = json_decode($data);
    return $json->items[0]->snippet->thumbnails->medium->url;

// Add featured image for videos
function addVideoThumb($post_ID) {


        if(get_field("source", $post_ID) == "youtube"):
            $videoID = get_field("youtube_video_id", $post_ID);
            $imageURL = getYoutubeThumb($videoID);          
            $videoID = get_field("vimeo_video_id", $post_ID);
            $imageURL = getVimeoThumb($videoID);
        //echo $imageURL;

        // download image from url
        $tmp = download_url($imageURL);

        $file = array(
            'name' => basename($imageURL),
            'tmp_name' => $tmp

        // create attachment from the uploaded image
        $attachment_id = media_handle_sideload($file, $post_ID);

        // set the featured image
        update_post_meta($post_ID, '_thumbnail_id', $attachment_id);

add_action('save_post_interel-tv-videos', 'addVideoThumb', 10, 3);

The function doesn't seem to be triggered at all as I tried to add a JavaScript alert to it and nothing pops up. Any help? Thanks in advance!

  • Check out this answer by Tom Nowell. Function media_sideload_image allows you to pass a URL to an image and uploads it to a post_id. That answer uses some hooks to assign that new image as a featured image which uses _thumbnail_id. by default.
    – Howdy_McGee
    Commented Apr 5, 2016 at 14:24
  • Also doesn't work. Think the problem is the function not being triggered at all. But no idea why...
    – rjpedrosa
    Commented Apr 5, 2016 at 14:51
  • Where are you putting these functions and which functions aren't firing?
    – Howdy_McGee
    Commented Apr 5, 2016 at 14:52
  • On functions.php The function addVideoThumb assigned to the add_action() doesn't seem to be triggered when I update a video.
    – rjpedrosa
    Commented Apr 5, 2016 at 15:07
  • Found a couple of issues with the code. Will fix them and get back here.
    – rjpedrosa
    Commented Apr 5, 2016 at 15:12

1 Answer 1


Finally sorted it out. As I am using Advanced Custom Fields, I need to use the acf/save_post hook with a priority greater than 10, so the get_field() functions are available.

Downside is that this hook runs for every post type. As opposed to the WP native save_post hook, with the ACF one you can't hook it for a specific custom post type.

So I also added a condition to check if the post is of type "interel-tv-videos", like if(!has_post_thumbnail($post_ID) and get_post_type($post_ID) == "interel-tv-videos"):

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