Question

I use a request dialog in my app where the user can send requests to their friends. Once the user sends the request i redirect the app to a page where it posts on the users page. I use the below code to get an access_token:

$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, 'https://graph.facebook.com/oauth/access_token?client_id='.APP_ID.'&client_secret='.APP_SECRET.'&redirect_uri=http://www.facebook.com/pages/Cosmetics/167231286678063?sk=app_233227910028874&grant_type=client_credentials');
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($ch, CURLOPT_HTTPAUTH, CURLAUTH_BASIC);
curl_setopt($ch, CURLOPT_SSL_VERIFYHOST,0);
curl_setopt($ch, CURLOPT_SSL_VERIFYPEER,0);

$token = curl_exec($ch);

$me = $facebook->api('/me?'.$token);

but when I try to post on the wall it shows this error:

Fatal error: Uncaught OAuthException: Invalid OAuth access token signature.

Answer 1

Why don’t you use PHP SDK 3.0.1 ?

Its easy if you use the sdk provided by facebook, here’s the sample for authentication using php sdk 3.0.1:

<?php

// Requires Facebook PHP SDK 3.0.1: https://github.com/facebook/php-sdk/
require ('facebook.php');

define('FACEBOOK_APP_ID',"YOUR-APP-ID-HERE");
define('FACEBOOK_SECRET',"YOUR-APP-API-SECRET-HERE");
define('REDIRECT_URI',"YOUR-REDIRECT-URL-HERE");
define('PERMISSIONS_REQUIRED', "publish_stream,user_photos");
$user = null;

$facebook = new Facebook(array(
    'appId' => FACEBOOK_APP_ID,
    'secret' => FACEBOOK_SECRET,
    'cookie' => true
));

$user = $facebook->getUser(); // Get the UID of the connected user, or 0 if the Facebook user is not connected.

if($user == 0) {
    // If the user is not connected to your application, redirect the user to authentication page
    /**
     * Get a Login URL for use with redirects. By default, full page redirect is
     * assumed. If you are using the generated URL with a window.open() call in
     * JavaScript, you can pass in display=popup as part of the $params.
     * 
     * The parameters:
     * - redirect_uri: the url to go to after a successful login
     * - scope: comma separated list of requested extended perms
     */

    $login_url = $facebook->getLoginUrl($params = array('redirect_uri' => REDIRECT_URI,'scope' => PERMISSIONS_REQUIRED));

    echo ("<script> top.location.href='".$login_url."'</script>");

} else {
    // if the user is already connected, then fetch access_token and user's information or show some content to logged in user.
    try
    {
        $access_token = $facebook->getAccessToken(); // Gives you current user's access_token

        $user = $facebook->api('/me'); // Gets User's information based on permissions the user has granted to your application.

    } catch(FacebookApiException $e){
        $results = $e->getResult();
        // Print results if you want to debug.
    }

}

?>