CodeIgniter 4 Google Login Tutorial

PHP provide SDK that helps developers to add google login feature in application.

Let’s start to integrate google login using php sdk library in codeIgniter 4 applications:

Step 1: Set Up Google API

Go to Google Cloud Console, and click on Select a Project to create New Project, then go to the Credentials tab on the sidebar, and click on Create Credentials and select OAuth 2.0 Client ID. And configure the OAuth consent screen by filling in the required fields.

Select Web Application in Under Application Type. And add Project URL or Callback URL to it. Click on Create. Note down your Client ID and Client Secret.

Step 2: Install Google PHP Client Library

Run the following composer command to install Google API PHP Client Library:

composer require google/apiclient

Step 3: Configure CodeIgniter

Create Google.php configuration file in app/Config/, and add YOUR_CLIENT_ID and YOUR_CLIENT_SECRET in it:

<?php

namespace App\Config;

use CodeIgniter\Config\BaseConfig;

class Google extends BaseConfig
{
    public $clientId = 'YOUR_CLIENT_ID';
    public $clientSecret = 'YOUR_CLIENT_SECRET';
    public $redirectUri = 'http://localhost/google-login/callback';
}

Step 4: Create Google Auth Controller

Go to app/Controllers/ controller directory, and create GoogleLogin.php file to handle google authentication:

<?php

namespace App\Controllers;

use CodeIgniter\Controller;
use Google\Client as GoogleClient;
use Google\Service\Oauth2 as GoogleOauth2;

class GoogleLogin extends Controller
{
    public function index()
    {
        return view('login');
    }

    public function googleAuth()
    {
        $config = config('Google');
        
        $client = new GoogleClient();
        $client->setClientId($config->clientId);
        $client->setClientSecret($config->clientSecret);
        $client->setRedirectUri($config->redirectUri);
        $client->addScope('email');
        $client->addScope('profile');
        
        $authUrl = $client->createAuthUrl();
        
        return redirect()->to($authUrl);
    }

    public function callback()
    {
        $config = config('Google');
        
        $client = new GoogleClient();
        $client->setClientId($config->clientId);
        $client->setClientSecret($config->clientSecret);
        $client->setRedirectUri($config->redirectUri);
        
        $code = $this->request->getVar('code');
        $client->fetchAccessTokenWithAuthCode($code);
        
        $oauth2 = new GoogleOauth2($client);
        $userInfo = $oauth2->userinfo->get();
        
        // Display user info
        echo 'Name: ' . $userInfo->name . '<br>';
        echo 'Email: ' . $userInfo->email . '<br>';
        echo 'Profile Picture: <img src="' . $userInfo->picture . '"><br>';
    }
}

Step 5: Create View

Go to app/Views/ directory and create login.php file that show google login button:

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Google Login in CodeIgniter 4 - Itcodstuff.com</title>
</head>
<body>
    <h1>Login Page</h1>
    <a href="<?= site_url('google-login') ?>">Login with Google</a>
</body>
</html>

Step 6: Define Routes

Edit app/Config/Routes.php file and add google authentication routes in it:

$routes->get('login', 'GoogleLogin::index');
$routes->get('google-login', 'GoogleLogin::googleAuth');
$routes->get('google-login/callback', 'GoogleLogin::callback');

Step 7: Test Application

Run the following command to start application server:

php spark serve

Now open browser and type url http://localhost:8080/login in it to test google login application.