title: How to save and retrieve custom metadata fields via YouTube API
body: <p>I'd like to store a string as a custom field within each YouTube video of a playlist.</p>
  
  <p>(To be specific, my website retrieves this playlist and shows the thumbnail image of each of its videos, and I want to display a quotation under each image.)</p>
  
  <p>I know from docs at <a href="https://developers.google.com/youtube/v3/docs/playlistItems/list" rel="nofollow noreferrer">https://developers.google.com/youtube/v3/docs/playlistItems/list</a> that I can retrieve details of a YouTube playlist by doing something like this:</p>
  
  <pre><code>$service = new Google_Service_YouTube($client);
  $queryParams = [
      'maxResults' =&gt; 50,
      'playlistId' =&gt; '{myID}'
  ];
  $response = $service-&gt;playlistItems-&gt;listPlaylistItems('id,snippet,contentDetails,status', $queryParams);
  </code></pre>
  
  <p>But from those docs and <a href="https://developers.google.com/youtube/v3/docs/videos" rel="nofollow noreferrer">https://developers.google.com/youtube/v3/docs/videos</a> and others, I haven't seen how to save any custom fields.</p>
  
  <p>I suppose I could use the "description" field, but that is not ideal since I'd rather the public-facing description be independent of this custom string field I'd like to save.</p>
  
  <p>How would you recommend achieving my goal (ideally without creating my own database)?</p>