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 FacebookFacebook([
      ''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.