title: Search for folder with parents set in google drive api
body: <p>I want to search for folder in google drive, but I need to deal with case that folder doesn't have parent.</p>
  
  <pre><code>$file = $this-&gt;service-&gt;files-&gt;listFiles(
                                  array('q' =&gt;  
                                         "mimeType = 'application/vnd.google-apps.folder' 
                                          and trashed = false 
                                          and name = '".$name."' 
                                          and '".$parent."' in parents" ));
  </code></pre>
  
  <p>I don't know how to set last parameter, according to <a href="https://developers.google.com/drive/v3/web/search-parameters" rel="nofollow noreferrer">documentation</a> it should be like that, but when parent is NULL it doesn't return anything.</p>