Download a Google Doc using the PHP library

At the time of writing this tip, the Zend_Gdata_Docs component of the PHP library does not contain the export/download functionality of the DocList API. Here is an example of using AuthSub and file_get_contents() to download a document as a .txt file:

function download($client, $url, $format=null) {
  $sessionToken = $client->getHttpClient()->getAuthSubToken();
  $opts = array(
    'http' => array(
      'method' => 'GET',
      'header' => "GData-Version: 3.0\r\n".
                  "Authorization: AuthSub token=\"$sessionToken\"\r\n"
    )
  );
  if ($url != null) {
    $url =  $url . "&exportFormat=$format";
  }
  return file_get_contents($url, false, stream_context_create($opts));
}

// TODO 1: setup a Zend_Gdata_Docs client in $docs_client
// TODO 2: fetch a $feed or $entry
$contentLink = $feed->entries[0]->content->getSrc();
$fileContents = download($docs_client, $contentLink, 'txt');
echo 'Contents of document "' . $feed->entries[0]->title . '":<hr>';
echo "<pre>$fileContents</pre>";