Fatal Error - Class 'League\OAuth2\Client\Provider\AbstractProvider' not found (phpMailer) - php

Question

I installed league/oauth2-client with composer and it created this line in composer.json
"league/oauth2-client": "2.2.0"
When I refreshed get_oauth_token.php page, this error still came out:
Fatal error: Class 'League\OAuth2\Client\Provider\AbstractProvider'
not found in C:\xampp\htdocs...\PHPMailer\get_oauth_token.php on
line 35
Here's get_oauth_token.php
<?php
/**
* Get an OAuth2 token from Google.
* * Install this script on your server so that it's accessible
* as [https/http]://<yourdomain>/<folder>/get_oauth_token.php
* e.g.: http://localhost/phpmail/get_oauth_token.php
* * Ensure dependencies are installed with 'composer install'
* * Set up an app in your Google developer console
* * Set the script address as the app's redirect URL
* If no refresh token is obtained when running this file, revoke access to your app
* using link: https://accounts.google.com/b/0/IssuedAuthSubTokens and run the script again.
* This script requires PHP 5.4 or later
* PHP Version 5.4
*/
namespace League\OAuth2\Client\Provider;
require './vendor/autoload.php';
use League\OAuth2\Client\Provider\Exception\IdentityProviderException;
use League\OAuth2\Client\Token\AccessToken;
use League\OAuth2\Client\Tool\BearerAuthorizationTrait;
use Psr\Http\Message\ResponseInterface;
session_start();
//If this automatic URL doesn't work, set it yourself manually
$redirectUri = isset($_SERVER['HTTPS']) ? 'https://' : 'http://' . $_SERVER['HTTP_HOST'] . $_SERVER['PHP_SELF'];
//$redirectUri = 'http://localhost/phpmailer/get_oauth_token.php';
//These details obtained are by setting up app in Google developer console.
$clientId = 'RANDOMCHARS-----duv1n2.apps.googleusercontent.com';
$clientSecret = 'RANDOMCHARS-----lGyjPcRtvP';
class Google extends AbstractProvider
{
use BearerAuthorizationTrait;
const ACCESS_TOKEN_RESOURCE_OWNER_ID = 'id';
/**
* #var string If set, this will be sent to google as the "access_type" parameter.
* #link https://developers.google.com/accounts/docs/OAuth2WebServer#offline
*/
protected $accessType;
/**
* #var string If set, this will be sent to google as the "hd" parameter.
* #link https://developers.google.com/accounts/docs/OAuth2Login#hd-param
*/
protected $hostedDomain;
/**
* #var string If set, this will be sent to google as the "scope" parameter.
* #link https://developers.google.com/gmail/api/auth/scopes
*/
protected $scope;
public function getBaseAuthorizationUrl()
{
return 'https://accounts.google.com/o/oauth2/auth';
}
public function getBaseAccessTokenUrl(array $params)
{
return 'https://accounts.google.com/o/oauth2/token';
}
public function getResourceOwnerDetailsUrl(AccessToken $token)
{
return ' ';
}
protected function getAuthorizationParameters(array $options)
{
if (is_array($this->scope)) {
$separator = $this->getScopeSeparator();
$this->scope = implode($separator, $this->scope);
}
$params = array_merge(
parent::getAuthorizationParameters($options),
array_filter([
'hd' => $this->hostedDomain,
'access_type' => $this->accessType,
'scope' => $this->scope,
// if the user is logged in with more than one account ask which one to use for the login!
'authuser' => '-1'
])
);
return $params;
}
protected function getDefaultScopes()
{
return [
'email',
'openid',
'profile',
];
}
protected function getScopeSeparator()
{
return ' ';
}
protected function checkResponse(ResponseInterface $response, $data)
{
if (!empty($data['error'])) {
$code = 0;
$error = $data['error'];
if (is_array($error)) {
$code = $error['code'];
$error = $error['message'];
}
throw new IdentityProviderException($error, $code, $data);
}
}
protected function createResourceOwner(array $response, AccessToken $token)
{
return new GoogleUser($response);
}
}
//Set Redirect URI in Developer Console as [https/http]://<yourdomain>/<folder>/get_oauth_token.php
$provider = new Google(
array(
'myClientId' => $clientId, //already inserted
'myClientSecret' => $clientSecret, //already inserted
'myRedirectUri' => $redirectUri, //already inserted
'scope' => array('https://mail.google.com/'),
'accessType' => 'offline'
)
);
if (!isset($_GET['code'])) {
// If we don't have an authorization code then get one
$authUrl = $provider->getAuthorizationUrl();
$_SESSION['oauth2state'] = $provider->getState();
header('Location: ' . $authUrl);
exit;
// Check given state against previously stored one to mitigate CSRF attack
} elseif (empty($_GET['state']) || ($_GET['state'] !== $_SESSION['oauth2state'])) {
unset($_SESSION['oauth2state']);
exit('Invalid state');
} else {
// Try to get an access token (using the authorization code grant)
$token = $provider->getAccessToken(
'authorization_code',
array(
'code' => $_GET['code']
)
);
// Use this to get a new access token if the old one expires
echo 'Refresh Token: ' . $token->getRefreshToken();
}
Can you explain me in detail what to do after having installed league/oauth2-client through composer require league/oauth2-client?
Thank you.

Answer 1

Had a similar issue and discovered its not stated explicitly in the official tutorial here.
The library league/oauth2-client requires you to install the provider you need seperately as there are multiple providers both official and third party here.
For google provider you would need
composer require league/oauth2-google
And refer to it like this
use League\OAuth2\Client\Provider\Google;