Added examples and reference to the blog post on how to write extractors

Author: Luciano Mammino

README.md

@@ -162,7 +162,7 @@ a better understanding of what every method does.
 
 ## Examples
 
-TODO
+Examples are available in the [examples](examples) directory.
 
 ## How to contribute
 
@@ -219,8 +219,8 @@ public function __construct()
 
 ### A small example
 
-I hope to have time to write a dedicated blog post to present a small example that explains, step by step, how to write a new extractor.
-In the meanwhile you can have a look at the [currently existing extractors](src/OAuth/UserData/Extractor/).
+I wrote [a dedicated blog post](http://loige.com/writing-a-new-extractor-for-php-oauth-user-data/) to present a small example that explains,
+step by step, how to write a new extractor.
 
 ## Contributors
 

examples/bootstrap.php

@@ -0,0 +1,37 @@
+<?php
+
+/**
+ * Bootstrap the library
+ */
+require_once __DIR__ . '/../vendor/autoload.php';
+
+/**
+ * Setup error reporting
+ */
+error_reporting(E_ALL);
+ini_set('display_errors', 1);
+
+/**
+ * Setup the timezone
+ */
+ini_set('date.timezone', 'Europe/Amsterdam');
+
+/**
+ * Create a new instance of the URI class with the current URI, stripping the query string
+ */
+$uriFactory = new \OAuth\Common\Http\Uri\UriFactory();
+$currentUri = $uriFactory->createFromSuperGlobalArray($_SERVER);
+$currentUri->setQuery('');
+
+/**
+ * @var array A list of all the credentials to be used by the different services in the examples
+ */
+$servicesCredentials = array(
+    'facebook' => array(
+        'key'       => 'put_your_app_key_here',
+        'secret'    => 'put_your_app_secret_here',
+    )
+);
+
+/** @var $serviceFactory \OAuth\ServiceFactory An OAuth service factory. */
+$serviceFactory = new \OAuth\ServiceFactory();

examples/facebook.php

@@ -0,0 +1,54 @@
+<?php
+
+/**
+ * Example of retrieving an authentication token of the Facebook service
+ * and extract user data. Based on the Lusitanian/PHPoAuthLib facebook example that can be
+ * found here: https://github.com/Lusitanian/PHPoAuthLib/blob/master/examples/facebook.php
+ */
+
+use OAuth\OAuth2\Service\Facebook;
+use OAuth\Common\Storage\Session;
+use OAuth\Common\Consumer\Credentials;
+use OAuth\UserData\ExtractorFactory;
+
+/**
+ * Bootstrap the example
+ */
+require_once __DIR__ . '/bootstrap.php';
+
+// Session storage
+$storage = new Session();
+
+// Setup the credentials for the requests
+$credentials = new Credentials(
+    $servicesCredentials['facebook']['key'],
+    $servicesCredentials['facebook']['secret'],
+    $currentUri->getAbsoluteUri()
+);
+
+// Instantiate the Facebook service using the credentials, http client and storage mechanism for the token
+/** @var $facebookService Facebook */
+$facebookService = $serviceFactory->createService('facebook', $credentials, $storage, array());
+
+if (!empty($_GET['code'])) {
+    // This was a callback request from facebook, get the token
+    $token = $facebookService->requestAccessToken($_GET['code']);
+
+    // Send a request with it
+    $result = json_decode($facebookService->request('/me'), true);
+
+    // Instantiate the facebook extractor
+    $extractorFactory = new ExtractorFactory();
+    $facebookExtractor = $extractorFactory->get($facebookService);
+
+    // Show some of the resultant data using the extractor
+    echo 'Your unique facebook user id is: ' . $facebookExtractor->getUniqueId() .
+            ' and your name is ' . $facebookExtractor->getFullName();
+
+} elseif (!empty($_GET['go']) && $_GET['go'] === 'go') {
+    $url = $facebookService->getAuthorizationUri();
+    header('Location: ' . $url);
+} else {
+    $url = $currentUri->getRelativeUri() . '?go=go';
+    echo "<a href='$url'>Login with Facebook!</a>";
+}