Question

I need to read, from a server, the stream of a specific fan page.
I tried to read the graph api
https://graph.facebook.com//feed?access_token=&limit=100
and it works.
What I need is to understand if the token will expire and how to renew it programmatically.
Now I generate my token through the http://developers.facebook.com/tools/explorer/ app.
Can you please help me?
I’m using the PHP sdk
thanks,
a.

Answer 1

You can read the facebook page using below codes and you can also get the specified fields

https://graph.facebook.com/$page_id/?fields=link,etc&access_token=page_access_token

or

$response = $fb->api($page_id .  '/?fields=link,etc&'. $access_token, 'GET')

Below is the solution for four scenarios

1.The token expires after expires time (2 hours is the default).
2.The user changes her password which invalidates the access token.
3.The user de-authorizes your app.
4.The user logs out of Facebook.

To ensure the best experience for your users, your app needs to be prepared to catch errors for the above scenarios. The following PHP code shows you how to handle these errors and retrieve a new access token.

When you redirect the user to the auth dialog, the user is not prompted for permissions if the user has already authorized your application. Facebook will return you a valid access token without any user facing dialog. However if the user has de-authorized your application then the user will need to re-authorize your application for you to get the access_token.

<?php
$app_id = "YOUR_APP_ID";
$app_secret = "YOUR_APP_SECRET"; 
$my_url = "YOUR_POST_LOGIN_URL";

// known valid access token stored in a database 
$access_token = "YOUR_STORED_ACCESS_TOKEN";

$code = $_REQUEST["code"];

// If we get a code, it means that we have re-authed the user 
//and can get a valid access_token. 
if (isset($code)) {
$token_url="https://graph.facebook.com/oauth/access_token?client_id="
  . $app_id . "&redirect_uri=" . urlencode($my_url) 
  . "&client_secret=" . $app_secret 
  . "&code=" . $code . "&display=popup";
$response = file_get_contents($token_url);
$params = null;
parse_str($response, $params);
$access_token = $params['access_token'];
}


// Attempt to query the graph:
$graph_url = "https://graph.facebook.com/me?"
. "access_token=" . $access_token;
$response = curl_get_file_contents($graph_url);
$decoded_response = json_decode($response);

//Check for errors 
if ($decoded_response->error) {
// check to see if this is an oAuth error:
if ($decoded_response->error->type== "OAuthException") {
  // Retrieving a valid access token. 
  $dialog_url= "https://www.facebook.com/dialog/oauth?"
    . "client_id=" . $app_id 
    . "&redirect_uri=" . urlencode($my_url);
  echo("<script> top.location.href='" . $dialog_url 
  . "'</script>");
}
else {
  echo "other error has happened";
}
} 
else {
// success
echo("success" . $decoded_response->name);
echo($access_token);
}

// note this wrapper function exists in order to circumvent PHP’s 
//strict obeying of HTTP error codes.  In this case, Facebook 
//returns error code 400 which PHP obeys and wipes out 
//the response.
function curl_get_file_contents($URL) {
$c = curl_init();
curl_setopt($c, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($c, CURLOPT_SSL_VERIFYPEER, false);
curl_setopt($c, CURLOPT_URL, $URL);
$contents = curl_exec($c);
$err  = curl_getinfo($c,CURLINFO_HTTP_CODE);
curl_close($c);
if ($contents) return $contents;
else return FALSE;
}
?>

for more details info you can visit this link
Thanks