title: Facebook User Access Token PHP
body: <p>As stated on the Facebook documentation, <strong><em>access tokens</em></strong> are portables, that means that an <strong><em>access token</em></strong> could be obtained on the <strong>front-end side</strong> of the application and passed to the <strong>back-end side</strong> to handle Graph API requests.</p>
  
  <p>The problem is: how to properly instantiate and setup the Access Token in the <strong>back-end</strong> side?</p>
  
  <p>I'm currently doing the following code:</p>
  
  <pre><code>use Facebook\Authentication\AccessToken;
  $accessToken = new AccessToken('{access-token goes here}');
  print_r($accessToken); // inspecting the token
  </code></pre>
  
  <p>When <strong><em>print_r</em></strong> is called, some of the token information are missing, such as the <strong><em>expiresAt</em></strong> attribute. This attribute, for instance, is present when the <strong><em>access token</em></strong> is generated by the <strong>FacebookRedirectLoginHelper::getAccessToken</strong> on the callback process.</p>
  
  <p>Does the lack of this attribute interferes on the flow of things? If so, then how to properly instantiate a portable <strong>Access Token</strong> in the <strong>back-end</strong>?</p>