# FacebookCanvasLoginHelper for the Facebook SDK for PHP
A helper class for getting a FacebookSession in a Canvas app
## Facebook\FacebookCanvasLoginHelper {#overview}
If your app is loaded through Canvas, Facebook sends a POST request with a signed request. This helper class will handle processing and validating that information with Facebook, and returns a `FacebookSession`.
Usage:
~~~~
$helper = new FacebookCanvasLoginHelper();
try {
$session = $helper->getSession();
} catch (FacebookRequestException $ex) {
// When Facebook returns an error
} catch (\Exception $ex) {
// When validation fails or other local issues
}
if ($session) {
// Logged in.
}
~~~~
## Instance Methods {#instance-methods}
### getSession {#getsession}
`getSession()`
Processes the POST request from Facebook, if present. Returns a `FacebookSession` or `null`.