Steve's Ramblings

One of the features of the old Facebook API was “off-line” access – basically where you could interact with Facebook in a “non-interactive” way : in other words a program or script could interact with Facebook on your behalf without you having to have a Facebook window open in your browser.

The new API also supports this but the documentation is not really totally clear on the “process” needed to do it.

So I sat down and worked it out. The code you are about to see is not neat, or tidy. It contains no proper error handling or checking apart from the bare minimum needed to make it work.

Pre-requisites

You will need:

• A Webserver
• PHP V5.x with CURL enabled
• A MySQL Database.
• A Facebook Account (preferably a developer account unless your friends like being spammed)
• A Facebook Application
• The Facebook Graph PHP-SDK which is available from the GitHub repository.

First of all we need to make sure that we have a table to store the session data in. We are actually storing all the session data : this might be overkill but as a lot of this is still undocumented I felt it was safer to store everything.

So at the start of our example lets do the dirty work with the database. If you were doing this properly you’d have this in a function which you called once, for example with a WordPress plugin you’d call it on plugin activation. But we’re not doing that here so …. and don’t forget to change those db_  parameters to match your system.

$db_server = "localhost";
$db_username = "dbuser";
$db_password = "dbpassword";
$db_name = "dbname";

# Lets connect to the Database and set up the table
mysql_connect($db_server,$db_username,$db_password);
mysql_select_db($db_name);
$ct_res = mysql_query("CREATE TABLE IF NOT EXISTS `facebook_user` (
   `session_key` VARCHAR( 80 ) NOT NULL ,
   `uid` VARCHAR( 80 ) NOT NULL ,
   `expires` VARCHAR( 80 ) NOT NULL ,
   `secret` VARCHAR( 80 ) NOT NULL ,
   `access_token` VARCHAR( 120 ) NOT NULL ,
   `sig` VARCHAR( 80 ) NOT NULL
   );"
);

OK So that’s the DB work done and each time we run the script it will create the table if its not there. Now we can set up the Facebook side of things. Don’t forget to change the path for the facebook.php file (which you did download  didn’t you?). You’ll also need the information about the Facebook Application you set up because I’m not letting you share mine! You may also want to review the permissions that are being granted – the ones in this code are the ones my Wordbooker application uses

# Now lets load the FB GRAPH API
require '../src/facebook.php';

// Create our Application instance.
global $facebook;
$facebook = new Facebook(array(
 'appId'  => '101001010101010101',
 'secret' => 'faafaffdfasdffsafsfsddfasd',
 'cookie' => false,
));

# Lets set up the permissions we need and set the login url in case we need it.
$par['req_perms'] = "publish_stream,
                    offline_access,
                    user_status,
                    read_stream,
                    email,
                    user_groups";
$loginUrl = $facebook->getLoginUrl($par);

The “heart” of the code is the get_check_session function. This function checks to see if we have a session stored in the database and if we do it returns it. If we don’t have a session but a session is being passed in via the URL it gets it, stores it and then returns it. If neither of these cases are true it returns nothing.

function get_check_session(){
  global $facebook;
  # This function basically checks for a stored session and if we have one returns it,
  #If we have no stored session then it gets one and stores it
  # OK lets go to the database and see if we have a session stored
  $sid=mysql_query("Select access_token from facebook_user");
  $session_id=mysql_fetch_row($sid);
  if (is_array($session_id)) {
    # We have a session ID so lets not get a new one
    # Put some session checking in here to make sure its valid
   try {
     $attachment =  array('access_token' => $session_id[0],);
     $ret_code=$facebook->api('/me', 'GET', $attachment);
    }
     catch (Exception $e) {
       # We don't have a good session so
       echo "woops";
      $res = mysql_query('delete from facebook_user where expires=0');
      return;
    }
  return $session_id[0];
 } 

 {
  # Are we coming back from a login with a session set?
  $session = $facebook->getSession();
  if (is_array($session)) {
   # Yes! so lets store it!
   $sql="insert into facebook_user (
               session_key,
               uid,
               expires,
               secret,
               access_token,
               sig)
             VALUES ('".$session['session_key']."','".
                        $session['uid']."','".
                        $session['expires']."','".
                        $session['secret'] ."','".
                        $session['access_token']."','".
                        $session['sig']."');";
   $res = mysql_query($sql);
   return $session['access_token'];
  }
 }
}

OK, believe it or not we are just about there with only a few more lines of code to go. Are you ready?

$access_token=get_check_session();
# If we've not got an access_token we need to login.
if ( is_null($access_token) ) {
echo '<a href="'. $loginUrl.'"><
img src="http://static.ak.fbcdn.net/rsrc.php/zB6N8/hash/4li2k73z.gif" alt="" /> ';
}
else {

# This is where you put your code.
$target=1010101010100110;
$attachment =  array(
 'access_token' => $access_token,
 'message' => 'Did a Test Post :',
 'name' => "Offline posting using stored tokens",
   'link' => "http://blogs.canalplan.org.uk/steve/2010/05/05/using-the-new-facebook-graph-api-off-line/",
  'description' => "This post was made using a stored access token",
  'picture'=>http://blogs.canalplan.org.uk/steve/files/2010/05/Screenshot-5-300x194.png",
			);

$ret_code=$facebook->api('/'.$target.'/feed', 'POST', $attachment);

echo "Returns : ";
var_dump($ret_code);
echo ""; 

$attachment =  array(
'access_token' => $access_token,
 'message' => "and this is a comment I've just made on the post using that same stored token",);

$ret_code=$facebook->api('/'.$ret_code['id'].'/comments', 'POST', $attachment);

echo "Returns : ";
var_dump($ret_code);
echo ""; 

}

Basically any code in the ELSE {} block is executed if you have a Facebook access_token. In the example what we do is post a message to a “target” which is a FB user ID (you can use names rather than numbers), and then we immediately comment on it. Which produces something like:

A Wall post and an associated comment made by the php code.

So there you go. Why not download the code and give it a go.