Listing all files from Google Drive - php

Question

I would like to list all the files from my Google drive to my "DriveFiles.php" file where I can display the files and its details. I am a beginner so a complete code will be helpful. Thanks.
My code:
<?php
require_once 'google-api-php-client/src/Google_Client.php';
require_once 'google-api-php-client/src/contrib/Google_DriveService.php';
require_once 'google-api-php-client/src/io/Google_HttpRequest.php';
require_once 'google-api-php-client/src/contrib/Google_Oauth2Service.php';
// initialize a client with application credentials and required scopes.
$client = new Google_Client();
$client->setClientId('CLIENT_ID');
$client->setClientSecret('CLIENT_SECRET');
$client->setRedirectUri('REDIRECT_URI');
$client->setScopes(array(
'https://www.googleapis.com/auth/drive',
'https://www.googleapis.com/auth/userinfo.email',
'https://www.googleapis.com/auth/userinfo.profile'));
$client->setUseObjects(true);
if (isset($_GET['code']))
{
session_start();
print_r($_SESSION);
$client->authenticate($_GET['code']);
$_SESSION['token'] = $client->getAccessToken();
$client->setAccessToken($_SESSION['token']);
// initialize the drive service with the client.
$services = new Google_DriveService($client);
retrieveAllFiles($services);
}
if(!$client->getAccessToken()){
$authUrl = $client->createAuthUrl();
echo '<a class="login" href="'.$authUrl.'">Login</a>';
}
function retrieveAllFiles($service) {
$result = array();
$pageToken = NULL;
do {
try {
$parameters = array();
if ($pageToken) {
$parameters['pageToken'] = $pageToken;
}
$files = $service->files->listFiles($parameters);
$result = array_merge($result, $files->getItems());
$pageToken = $files->getNextPageToken();
} catch (Exception $e) {
print "An error occurred: " . $e->getMessage();
$pageToken = NULL;
}
} while ($pageToken);
return $result;
}
?>
When I execute the code I get the following error:
Fatal error: Uncaught exception 'Google_Exception' with message 'Cant
add services after having authenticated' in
D:\GT_local\Public\google-api-php-client\src\Google_Client.php:115
Stack trace: #0
D:\GT_local\Public\google-api-php-client\src\contrib\Google_DriveService.php(1258):
Google_Client->addService('drive', 'v2') #1
D:\GT_local\Public\quickstart.php(55):
Google_DriveService->__construct(Object(Google_Client)) #2 {main}
thrown in
"FILE_LOCATION(C://google-api-php-client\src\Google_Client.php on line
115)"
How can I fix this.

Answer 1

Try starting the session in the top of the script, and try to do all authentication before you have to do any operation. Also use the most recent API so you can use this libraries:
require_once '/src/Google/autoload.php';
require_once '/src/Google/Client.php';
require_once '/src/Google/Service/Oauth2.php';
require_once '/src/Google/Service/Drive.php';