Facebook Login

Users can be asked to log into a web application with the help of Social media login, also called SSO. This way users need not create a new account. Instead, users can use their existing social media account information to log in. Some examples of social media login include: Google, Facebook, LinkedIn, Apple.

In this chapter, we shall explain how to activate logging into a PHP application with Facebook credentials.

The first step to add Facebook login feature is to create a Facebook app. Visit https://developers.facebook.com/apps/creation/ and sign in with your Facebook account.

Next, enter the name of the Facebook app you want to create −

Go in the App settings and obtain Application ID and secret code −

Select platform as website −

Next, you need to set Up Facebook SDK in PHP. Download the Facebook SDK for PHP from “https://packagist.org/packages/facebook/php-sdk” or use composer: composer require “facebook/graph-sdk-v5”. Extract the SDK files to a directory accessible by your PHP application.

To configure Facebook SDK in PHP Code, include the Facebook SDK autoloader in your PHP file: require_once __DIR__ . ‘/vendor/autoload.php’;

Set up your app’s access token and app secret −

$app_id='YOUR_APP_ID';$app_secret='YOUR_APP_SECRET';

Next, create Facebook Login Button. Create an HTML button and add the Facebook login JavaScript SDK to trigger the login flow −

<button id="facebook-login-button">Login with Facebook</button>

Include the Facebook JavaScript SDK −

<script src="https://connect.facebook.net/en_US/sdk.js#xfbml=1&version=v13.0&appId=YOUR_APP_ID&autoLogApp=true" async defer></script>

Create a PHP script to handle the Facebook login callback −

<?php
   session_start();

   $fb = new Facebook\Facebook([
      'app_id' => $app_id,
      'app_secret' => $app_secret,
      'default_graph_version' => 'v13.0',
   ]);

   $helper = $fb->getRedirectLoginHelper();
   $accessToken = $helper->getAccessToken();

   if ($accessToken) {
      // User is logged in, handle their data
      $user = $fb->get('/me', ['fields' => 'id,name,email']);
      $_SESSION['user_data'] = $user;
      header('Location: profile.php');
   } else {
      // User is not logged in, redirect to login page
      $loginUrl = $helper->getLoginUrl(['scope' => 'public_profile,email']);
      header('Location: ' . $loginUrl);
   }
?>

After successful login, store user data in the session and redirect to a protected page. On protected pages, check the session for user data to verify access.

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