Is there a way to check if Facebook access token i

Question

My site utilizes lifetime access tokens (offline_access). However, if the user changes his/her password, the access token gets reset. Is there a method to check if the current access token is valid before making calls to the Graph API? Thanks for your time.

Answer 1

You can check the token using the token debug service , take a look here

https://graph.facebook.com/debug_token?input_token=INPUT_TOKEN&access_token=ACCESS_TOKEN

https://developers.facebook.com/docs/howtos/login/debugging-access-tokens/

Answer 2

        //When user access token expires user must be logged in and renew the access token him self.it is a Facebook policy 
        //you can overcome this by sending email to users who have expired access token.
        //create a table of successful sending to monitor sending process
        //if any failure happened with the user an email is sent to him to ask him to activate there account again.with a link to your subscription page.
        //and here is the code should be written on that page. 
         $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_URL, $URL);
        $contents = curl_exec($c);
        $err  = curl_getinfo($c,CURLINFO_HTTP_CODE);
        curl_close($c);
        if ($contents) return $contents;
        else return FALSE;
      }

Answer 3

The real time updates would allow you to solve this problem, but it would be pretty complicated. Basically, you can subscribe to updates that will tell you 1) if the user removed the app or 2) if the user removed permissions. You could use this to store the current permissions of the faceboook user. This way, if the user removed your app you would know that the access token is expired.

Real time updates is actually facebooks recommended way of handling permissions. Many apps make api calls every time a page is loaded to check for permissions. This tends to be slow and unreliable.

Answer 4

Offline - it is not possible

Ask that user has given permission or not:

https://graph.facebook.com/{facebook-id}/permissions?access_token={access-token}

If access token is invalid then it will give error:

{  
   error:{  
      message:"The access token could not be decrypted",
      type:"OAuthException",
      code:190
   }
}

Otherwise it will give list of permission that user has given:

data:[  
   {  
      installed:1,
      ...... permission list......... 
      bookmarked:1
   }
]

Answer 5

Otto's answer of the facebook post seems to be the official response on this question, however it uses straight PHP instead of the SDK and also uses JS to resolve the issue instead of PHP. If you are using PHP to check for a valid session you often need a PHP method of ensuring a valid session in order to continue.

The following code checks for the me object with the graph API. If an exception is thrown it destroys* the current Facebook session.

try{
    $facebook->api('/me');
}
catch( FacebookApiException $e ){
    $facebook->destroySession();
}

This forces later graph calls to instantiate a new Facebook session. This at least gives you access to public data so that you can render pages do not require FB user permissions:

$facebook->api('/userName');

To reobtain user permission access the user will need to login to your app (this is distinct from being logged into Facebook itself). You can do this with JS or with PHP:

$facebook->getLoginUrl();

*Note the destroySession() call is not in a tagged release of the PHP SDK yet. Use the master branch or patch it in.

Answer 6

Basically, FB wants you to poll for it, or to detect the case and redirect the user to get a reauth to occur. Annoying, but official:

(Old, out of date link. See below) https://developers.facebook.com/blog/post/500/

Edit: Facebook changed their link structure without redirects. Not surprised.

https://developers.facebook.com/blog/post/2011/05/13/how-to--handle-expired-access-tokens/