having trouble sending facebook notification via ajax call to php - facebook-graph-api

Question

In my javascript I have a click event that triggers an ajax call to the php page where I send my notification from. I chose to do it this way because the documentation advises against using your app secret in any client side code, and the notifications parameters requires an access token that you can only get using the app secret.
The problem I'm having is that even though I'm logged in, $facebook->getUser() is returning 0 in php, so the api call I make afterwards to send the notification wont work. My user is already logged in via the client side code, so how do I get the message to the php that they're logged in so the notification can be sent.
//JS
$.ajax({
url : "http://xxxxxo/bn/notification.php",
type : 'POST',
data: {notify: notify },
success : function (result) {
console.log(result);
},
error : function () {
alert("error sending notification");
}
});//closes ajax
//PHP
<?php
require_once(dirname(__FILE__).'/php-sdk/facebook.php') ;
$APPLICATION_ID = '1402xxxxx7';
$APPLICATION_SECRET = 'ce71d6bbxxxxx5f55a';
$fb_app_url = "http://apps.facebook.com/myAPP";
$config = array();
$config['appId'] = $APP_ID;
$config['secret'] = $APP_SECRET;
$config['cookie'] = true;
$facebook = new Facebook($config) or die('Error is here!');
$facebook = new Facebook(array(
'appId' => $APP_ID,
'secret' => $APP_SECRET,
'fileUpload' => true
));
$notify = $_REQUEST['notify'];
$userid = $facebook->getUser();
/*IF WE HAVE A LOGGED IN USER AND THE 'NOTIFY' REQUEST VALUE, THEN SEND THE NOTIFICATION.
BUT MY USER ID IS 0. HOW DO I GET PHP TO RECOGNIZE ME AS LOGGED IN WITHOUT HAVING TO FORCE MY USER TO LOG IN VIA PHP AFTER THEY'VE ALREADY LOGGED IN CLIENT SIDE?*/
if($userid && $notify){
$token_url ="https://graph.facebook.com/oauth/access_token?" .
"client_id=" . $APP_ID .
"&client_secret=" . $APP_SECRET .
"&grant_type=client_credentials";
$app_token = file_get_contents($token_url);
$app_token = str_replace("access_token=", "", $app_token);
$data = array(
'href'=> 'https://apps.facebook.com/thebringernetwork/',
'access_token'=> $app_token,
'template'=> 'test'
);
$sendnotification = $facebook->api('/1622649653/notifications', 'post', $data);
}else{
//handle error
}
?>

Answer 1

The first thing I noticed is that you define your app id as $APPLICATION_ID but use it as $APP_ID (and the same goes for your app secret). But since you didn't mention any errors and $facebook->getUser(); executes I'm guessing this is just a bad copy-paste.
Now for the sake of answering this question I'm going to presume that you are using the latest versions of both JS and PHP SDKs. These use oauth 2.0 and change the way you pass the login information from JS to PHP.
According to Facebook Developer Blog removing $config['cookie'] = true; and setting oauth to true in your JS configuration should work. Just make sure to refresh the site after the login.
The solution I've found in my own project is to disable cookies altogether and simply pass the access token to my PHP script.
In your JS call your PHP script like this (make sure to call this after the JS login!):
$.ajax({
url : "http://xxxxxo/bn/notification.php",
type : 'POST',
data: {
notify: notify,
token: FB.getAuthResponse()['accessToken'] // add your access token
},
success : function (result) {
console.log(result);
},
error : function () {
alert("error sending notification");
}
});
And in your PHP script add this after creating the FB object.
$facebook->setAccessToken($_POST['token']); // set the users access token
Doing things this way will also get rid of any need to refresh the website after the login.

Answer 2

Yes, this is a common problem when using the PHP SDK in combination with AJAX:
When you make an AJAX request, the PHP SDK deletes the cookies where the authorization information are stored, and then the next call to getUser will just return 0, because this method tries to find the current user id in those cookies – apparently there is something in the OAuth 2.0 spec that demands this behavior to prevent some sort of click-jacking attack.
But the info will still be stored in the session, so you can read the user id (and the user access token, should you need it) from there:
$user_id = $_SESSION['fb_YourAppIdHere_user_id'];
$user_access_token = $_SESSION['fb_YourAppIdHere_access_token'];
Replace YourAppIdHere with your app id (so it becomes fb_1234567890_user_id resp. fb_1234567890_access_token) to get the correct names of those session keys.