🔐 Login with Facebook using PHP SDK

This project demonstrates how to implement Facebook Login using PHP SDK. Users can log in using their Facebook account instead of filling long registration forms.

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🚀 Features

• Login with Facebook account
• Fetch user profile data
• Session-based authentication
• Logout functionality

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📁 Project Structure

index.php
welcome.php
fb-callback.php
fb-config.php
logout.php

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⚙️ Facebook App Setup

1. Go to Facebook Developers
2. Create a new app
3. Add Facebook Login product
4. Go to Settings → Basic
   • Copy App ID
   • Copy App Secret
5. Go to Facebook Login → Settings
   • Add Callback URL
     Example:

     http://localhost/fb-callback.php
     

6. Enable:
   • Client OAuth Login
   • Web OAuth Login
7. Set app status to Live

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⚙️ fb-config.php

<?php
session_start();

require_once 'php-graph-sdk-5.x/src/Facebook/autoload.php';

$fb = new Facebook\Facebook([
  'app_id' => 'YOUR_APP_ID',
  'app_secret' => 'YOUR_APP_SECRET',
  'default_graph_version' => 'v3.2',
]);

$helper = $fb->getRedirectLoginHelper();
?>

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🔑 index.php (Login Button)

<?php
include_once('fb-config.php');

$permissions = ['email'];
$loginUrl = $helper->getLoginUrl('http://localhost/fb-callback.php', $permissions);
?>

<a href="<?php echo htmlspecialchars($loginUrl); ?>">
    Login with Facebook
</a>

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🔄 fb-callback.php

<?php
include_once('fb-config.php');

try {
  $accessToken = $helper->getAccessToken();
} catch(Exception $e) {
  echo 'Error: ' . $e->getMessage();
  exit;
}

if (!isset($accessToken)) {
  echo 'Access token not found!';
  exit;
}

$res = $fb->get('/me', $accessToken->getValue());
$user = $res->getDecodedBody();

$_SESSION['fbUserId'] = $user['id'];
$_SESSION['fbUserName'] = $user['name'];
$_SESSION['fbAccessToken'] = $accessToken->getValue();

header('Location: welcome.php');
exit;
?>

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👋 welcome.php

<?php
session_start();

if(!isset($_SESSION['fbUserId'])){
    header('Location: index.php');
    exit;
}
?>

<h2>Welcome <?php echo $_SESSION['fbUserName']; ?></h2>
<a href="logout.php">Logout</a>

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🚪 logout.php

<?php
session_start();

session_destroy();

header('Location: index.php');
exit;
?>

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📦 Requirements

• PHP (7+ recommended)
• Facebook PHP SDK
• Web server (XAMPP / WAMP / LAMP)

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⚠️ Important Notes

• Replace YOUR_APP_ID and YOUR_APP_SECRET
• Use HTTPS in production
• Keep App Secret secure
• Handle errors properly in production

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📄 License

Free to use and modify.