Class 'Silex\Application' not found - php

Question

I’ve done with google sign-up, I want to ask regarding google token_id authentication. Google issues a token-id to every user which changes on every sign-in, I am getting that token-id when the user sign-in, I want to authenticate that token-id from google to verify if the sign-in was original or fake. I am using this php api provided by google, but it is continuously giving this error:
Uncaught Error: Class 'Silex\Application' not found in C:\xampp\htdocs\final\gplus-verifytoken-php-master\verify.php:23
Stack trace: #0 {main} thrown in C:\xampp\htdocs\final\gplus-verifytoken-php-master\verify.php on line 23
require_once __DIR__.'/vendor/autoload.php';
require_once __DIR__.'/google-api-php-client/src/Google_Client.php';
use Symfony\Component\HttpFoundation\Request;
use Symfony\Component\HttpFoundation\Response;
const CLIENT_ID = 'xyz';
const CLIENT_SECRET = 'xyz';
const APPLICATION_NAME = "xyz";
$client = new Google_Client();
$client->setApplicationName(APPLICATION_NAME);
$client->setClientId(CLIENT_ID);
$client->setClientSecret(CLIENT_SECRET);
$app = new Silex\Application();
$app['debug'] = true;
$app->register(new Silex\Provider\TwigServiceProvider(), array(
'twig.path' => __DIR__,
));
$app->register(new Silex\Provider\SessionServiceProvider());
// Initialize a session for the current user, and render index.html.
$app->get('/', function () use ($app) {
return $app['twig']->render('index.html', array(
'CLIENT_ID' => CLIENT_ID,
'APPLICATION_NAME' => APPLICATION_NAME
));
});
// Verify an ID Token or an Access Token.
// Example URI: /verify?id_token=...&access_token=...
$app->post('/verify', function (Request $request) use($app, $client) {
$id_token = "eyJhbGciOiJSUzI1NiIsImtpZCI6ImE0MzY0YjVmYjliODYxYzNhYTRkYTg5NWExMjk5NzZjMjgyZGJmYzIifQ.eyJpc3MiOiJhY2NvdW50cy5nb29nbGUuY29tIiwiaWF0IjoxNDg1NDEyMjQ1LCJleHAiOjE0ODU0MTU4NDUsImF0X2hhc2giOiJMSV9DTWxzeG1lSTdvQm9lSUxoSjZRIiwiYXVkIjoiNDY4MzU1OTM0NzMzLXZqNnRkdDJtazEwZ3R0OHJvZGY2bG84MHM4czdtdTRrLmFwcHMuZ29vZ2xldXNlcmNvbnRlbnQuY29tIiwic3ViIjoiMTEyNjE1NTE5MDY0MTc3ODI0NTgzIiwiZW1haWxfdmVyaWZpZWQiOnRydWUsImF6cCI6IjQ2ODM1NTkzNDczMy12ajZ0ZHQybWsxMGd0dDhyb2RmNmxvODBzOHM3bXU0ay5hcHBzLmdvb2dsZXVzZXJjb250ZW50LmNvbSIsImVtYWlsIjoibWdoYXphbmZhcmFsaWtoYW4wOUBnbWFpbC5jb20ifQ.Bpa2_zeVebQ7xtKXvuEell50bvUtKOGb5ZertUZGvzGWXnlA-c2kw4Mvko9Xd4JI_R4wbFoyBtrGCiK0jAlJMgaIH8p3wJbzNKPZ-gPFJdX8mv4v42v8-9urGM7rRUCDylz16WEcR1A2qOmEcNCpCf0_FGNpChl8sc8q8zvTnIb_zYYHp_V7ebR2RlUuO2z9G5YzBN3hZDnmen1xLStmNmYKsIiP5ypMqbWaLjnXJjre6bjTuIGymg_phDYDmwWMVTJyx88zmKAfwQTCh2u3qe_fkCDxxm0MO2wC29__q4uc0BfUNdH62GOrNTBJXmPTUZuT1vdUhzz4CLu1KUohWg";
/*$id_token = $request->get("id_token");*/
$access_token = $request->get("access_token");
$token_status = Array();
$id_status = Array();
if (!empty($id_token)) {
// Check that the ID Token is valid.
try {
// Client library can verify the ID token.
$jwt = $client->verifyIdToken($id_token, CLIENT_ID)->getAttributes();
$gplus_id = $jwt["payload"]["sub"];
$id_status["valid"] = true;
$id_status["gplus_id"] = $gplus_id;
$id_status["message"] = "ID Token is valid.";
} catch (Google_AuthException $e) {
$id_status["valid"] = false;
$id_status["gplus_id"] = NULL;
$id_status["message"] = "Invalid ID Token.";
}
$token_status["id_token_status"] = $id_status;
}
$access_status = Array();
if (!empty($access_token)) {
$access_status["valid"] = false;
$access_status["gplus_id"] = NULL;
// Check that the Access Token is valid.
$reqUrl = 'https://www.googleapis.com/oauth2/v1/tokeninfo?access_token=' .
$access_token;
$req = new Google_HttpRequest($reqUrl);
$tokenInfo = json_decode(
$client::getIo()->authenticatedRequest($req)
->getResponseBody());
if ($tokenInfo->error) {
// This is not a valid token.
$access_status["message"] = "Invalid Access Token.";
} else if ($tokenInfo->audience != CLIENT_ID) {
// This is not meant for this app. It is VERY important to check
// the client ID in order to prevent man-in-the-middle attacks.
$access_status["message"] = "Access Token not meant for this app.";
} else {
$access_status["valid"] = true;
$access_status["gplus_id"] = $tokenInfo->user_id;
$access_status["message"] = "Access Token is valid.";
}
$token_status["access_token_status"] = $access_status;
}
return $app->json($token_status, 200);
});
$app->run();

Answer 1

I did like this
composer install (after that run this command)
composer dump-autoload
it is working for me

Answer 2

If your Framework don't work after migration.
or see Class 'Silex\Application' not found.
Delete "vendor" folder after composer install.
Working for me