Google OAuth 2.0 refresh token for web application with public access

Question

I\'m getting the following error:

The OAuth 2.0 access token has expired, and a refresh token is not available. Refresh tokens are not returned for re

Answer 1

Each access_token expires after a few seconds and need to be refreshed by refresh_token, "Offline access" is what you are looking for. Here you can follow the documentation:

https://developers.google.com/accounts/docs/OAuth2WebServer#offline

To obtain a refresh_token you have to run this code only one time:

require_once 'Google/Client.php';

$client = new Google_Client();
$client->setClientId('{MY_CLIENT_ID}.apps.googleusercontent.com');
$client->setClientSecret('{MY_KEY}');
$client->setRedirectUri('{MY_REDIRECT_URI}');
//next two line added to obtain refresh_token
$client->setAccessType('offline');
$client->setApprovalPrompt('force');
$client->setScopes(array('https://www.googleapis.com/auth/gmail.readonly'));

if (isset($_GET['code'])) {
    $credentials = $client->authenticate($_GET['code']);  

    /*TODO: Store $credentials somewhere secure */

} else {
    $authUrl = $client->createAuthUrl();
    print "<a class='login' href='$authUrl'>Connect Me!</a>";
}

$credentials includes an access token and a refresh token. You have to store this to obtain new access tokens at any time. So when you wanted to make a call to api:

require_once 'Google/Client.php';
require_once 'Google/Service/Gmail.php';

/*TODO: get stored $credentials */

$client = new Google_Client();
$client->setClientId('{MY_CLIENT_ID}.apps.googleusercontent.com');
$client->setRedirectUri('{MY_REDIRECT_URI}');
$client->setClientSecret('{MY_KEY}');
$client->setScopes(array('https://www.googleapis.com/auth/gmail.readonly'));
$client->setAccessToken($credentials);

$service = new Google_Service_Gmail($client);