Facebook Graph API session expiration - php

Question

I use the following PHP code to publish random messages from my database to my Facebook fan page:
require_once('src/facebook.php');
$appid = 'MY_APP_ID';
$appsecret = 'APP_SECRET';
$pageid = 'MY_PAGE_ID';
$token = 'MY_ACCESS_TOKEN';
// Create our Application instance (replace this with your appId and secret).
$facebook = new Facebook(array(
'appId' => $appid,
'secret' => $appsecret,
));
$message = 'Hello World';
//Information that makes up the facebook page post
$attachment = array(
'access_token' => $token,
'message' => $message
);
//Try to post to the facebook page
try{
$res = $facebook->api('/'.$pageid.'/feed','POST',$attachment);
} catch (Exception $e){
echo $e->getMessage();
}
And here is src/facebook.php - https://github.com/facebook/facebook-php-sdk/blob/master/src/facebook.php
But it return the error message something like this:
Error validating access token: Session has expired at unix time 1339020000. The current unix time is 1339022625.
So my question is what changes should I do in my code ?
P.S: I also looked relevant questions about session expiration, but none of them helped me.
Thanks in advance.

Answer 1

I'm assuming that you are using your user access token and not a page access token in this case.
You should be authenticating against the application with the manage_pages permission which will give you access to retrieve access tokens for your page. These have a longer expiration period.
After authorizing this permission and retrieving a valid access token for the current user, you should make a request to the following endpoint to retrieve a list of pages and applications you manage:
https://graph.facebook.com/me/accounts?access_token=USER_ACCESS_TOKEN
In this response is included an access token for these pages and applications:
{
"data": [
{
"name": "PAGE_TITLE",
"access_token": "PAGE_ACCESS_TOKEN",
"category": "PAGE_CATEGORY",
"id": "PAGE_ID"
},
You can see more information about this here:
https://developers.facebook.com/docs/authentication/pages/
Updated
For expired access token you will need to reauthenticate your user by accessing your app via a browser and following the authentication flow.
The documentation on how to handle this is here:
http://developers.facebook.com/docs/authentication/access-token-expiration/
You can then request a longer lived access token these do still expire. You can see information about how to request one of these here under scenario 4:
http://developers.facebook.com/roadmap/offline-access-removal/