Github Home:

https://github.com/facebookarchive/php-graph-sdk/tree/master/docs

Install

composer require facebook/graph-sdk

Sample code to get login URL:

$fb = new Facebook\Facebook([
  'app_id' => '{app-id}',
  'app_secret' => '{app-secret}',
  'default_graph_version' => 'v2.10',
  ]);

$helper = $fb->getRedirectLoginHelper();

$permissions = ['email']; // Optional permissions
$loginUrl = $helper->getLoginUrl('https://example.com/fb-callback.php', $permissions);

echo '<a href="' . $loginUrl . '">Log in with Facebook!</a>';

Sample code to get access token

$fb = new Facebook\Facebook([
  'app_id' => '{app-id}',
  'app_secret' => '{app-secret}',
  'default_graph_version' => 'v2.10',
  ]);

$helper = $fb->getRedirectLoginHelper();

try {
  $accessToken = $helper->getAccessToken();
} catch(Facebook\Exception\ResponseException $e) {
  // When Graph returns an error
  echo 'Graph returned an error: ' . $e->getMessage();
  exit;
} catch(Facebook\Exception\SDKException $e) {
  // When validation fails or other local issues
  echo 'Facebook SDK returned an error: ' . $e->getMessage();
  exit;
}

if (! isset($accessToken)) {
  if ($helper->getError()) {
    header('HTTP/1.0 401 Unauthorized');
    echo "Error: " . $helper->getError() . "\n";
    echo "Error Code: " . $helper->getErrorCode() . "\n";
    echo "Error Reason: " . $helper->getErrorReason() . "\n";
    echo "Error Description: " . $helper->getErrorDescription() . "\n";
  } else {
    header('HTTP/1.0 400 Bad Request');
    echo 'Bad request';
  }
  exit;
}

Sample code to get long live token

if (! $accessToken->isLongLived()) {
  // Exchanges a short-lived access token for a long-lived one
  try {
    $accessToken = $oAuth2Client->getLongLivedAccessToken($accessToken);
  } catch (Facebook\Exception\SDKException $e) {
    echo "<p>Error getting long-lived access token: " . $e->getMessage() . "</p>\n\n";
    exit;
  }

  echo '<h3>Long-lived</h3>';
  var_dump($accessToken->getValue());
}

Get login user data

try {
  // Get the \Facebook\GraphNodes\GraphUser object for the current user.
  // If you provided a 'default_access_token', the '{access-token}' is optional.
  $response = $fb->get('/me', '{access-token}');
} catch(\Facebook\Exceptions\FacebookResponseException $e) {
  // When Graph returns an error
  echo 'Graph returned an error: ' . $e->getMessage();
  exit;
} catch(\Facebook\Exceptions\FacebookSDKException $e) {
  // When validation fails or other local issues
  echo 'Facebook SDK returned an error: ' . $e->getMessage();
  exit;
}

$me = $response->getGraphUser();
echo 'Logged in as ' . $me->getName();

Note:

Please be aware, that there are issues when using the Facebook SDK together with Guzzle 6.x. php-graph-sdk v5.x only works with Guzzle 5.x out of the box. However, there is a workaround to make it work with Guzzle 6.x.

Brand Rules

https://developers.facebook.com/docs/facebook-login/userexperience/#buttondesign

User click cancel and redirect back with some params

https://xxxx.com/member/fb/listener?error=access_denied&error_code=200&error_description=Permissions+error&error_reason=user_denied&state=1bc5dafaf19a7bf66a0167a0b251c214#_=_

 

Reference:

1. Facebook SDK for PHP
   https://github.com/facebookarchive/php-graph-sdk/tree/master/docs
2. Login button:
   https://developers.facebook.com/docs/facebook-login/web/login-button/#——–
3. Permissions
   https://developers.facebook.com/docs/permissions/reference#user-data
4. Possible problem
   https://stackoverflow.com/questions/31520593/facebook-php-sdk-5-api-2-4-cross-site-request-forgery-validation-failed-r/36684861#36684861