login with facebook php

1/login.php
2  session_start();
3$fb = new Facebook\Facebook([
4  'app_id' => '{app-id}', // Replace {app-id} with your app id
5  'app_secret' => '{app-secret}',
6  'default_graph_version' => 'v3.2',
7  ]);
8
9$helper = $fb->getRedirectLoginHelper();
10
11$permissions = ['email']; // Optional permissions
12$callbackUrl = htmlspecialchars('https://example.com/fb-callback.php');
13$loginUrl = $helper->getLoginUrl($callbackUrl, $permissions);
14
15echo '<a href="' . $loginUrl . '">Log in with Facebook!</a>';
16
17
18/fb-callback.php
19  session_start();
20$fb = new Facebook\Facebook([
21  'app_id' => '{app-id}', // Replace {app-id} with your app id
22  'app_secret' => '{app-secret}',
23  'default_graph_version' => 'v3.2',
24  ]);
25
26$helper = $fb->getRedirectLoginHelper();
27
28try {
29  $accessToken = $helper->getAccessToken();
30} catch(Facebook\Exceptions\FacebookResponseException $e) {
31  // When Graph returns an error
32  echo 'Graph returned an error: ' . $e->getMessage();
33  exit;
34} catch(Facebook\Exceptions\FacebookSDKException $e) {
35  // When validation fails or other local issues
36  echo 'Facebook SDK returned an error: ' . $e->getMessage();
37  exit;
38}
39
40if (! isset($accessToken)) {
41  if ($helper->getError()) {
42    header('HTTP/1.0 401 Unauthorized');
43    echo "Error: " . $helper->getError() . "\n";
44    echo "Error Code: " . $helper->getErrorCode() . "\n";
45    echo "Error Reason: " . $helper->getErrorReason() . "\n";
46    echo "Error Description: " . $helper->getErrorDescription() . "\n";
47  } else {
48    header('HTTP/1.0 400 Bad Request');
49    echo 'Bad request';
50  }
51  exit;
52}
53
54// Logged in
55echo '<h3>Access Token</h3>';
56var_dump($accessToken->getValue());
57
58// The OAuth 2.0 client handler helps us manage access tokens
59$oAuth2Client = $fb->getOAuth2Client();
60
61// Get the access token metadata from /debug_token
62$tokenMetadata = $oAuth2Client->debugToken($accessToken);
63echo '<h3>Metadata</h3>';
64var_dump($tokenMetadata);
65
66// Validation (these will throw FacebookSDKException's when they fail)
67$tokenMetadata->validateAppId('{app-id}'); // Replace {app-id} with your app id
68// If you know the user ID this access token belongs to, you can validate it here
69//$tokenMetadata->validateUserId('123');
70$tokenMetadata->validateExpiration();
71
72if (! $accessToken->isLongLived()) {
73  // Exchanges a short-lived access token for a long-lived one
74  try {
75    $accessToken = $oAuth2Client->getLongLivedAccessToken($accessToken);
76  } catch (Facebook\Exceptions\FacebookSDKException $e) {
77    echo "<p>Error getting long-lived access token: " . $e->getMessage() . "</p>\n\n";
78    exit;
79  }
80
81  echo '<h3>Long-lived</h3>';
82  var_dump($accessToken->getValue());
83}
84
85$_SESSION['fb_access_token'] = (string) $accessToken;
86
87// User is logged in with a long-lived access token.
88// You can redirect them to a members-only page.
89//header('Location: https://example.com/members.php');