Question

In the PHP 3.0 SDK there is no getSession() or any session handling from outside the Facebook api available. Some days ago the developers of facebook have also somehow updated the JavaScript sdk, according to this blog entry and this bug report.

Within the last few days, a change was
introduced into the hosted JS SDK
which broke all compatility between it
and the current PHP SDK (2.x and 3.x).
Developers who utilize both the JS and
PHP SDK on their websites are likely
to see server-side API failure.

However, I don’t know if that really effects my problem. Like in this question’s answer I am retrieving the access token of the OAuth dialog with PHP and save the new access token in the session.

Current workaround

The following code shows how I am handling this sessions. $_REQUEST['session'] is the content of the response of the OAuth dialog.

if(isset($_REQUEST['session'])) {

    $response = json_decode(stripslashes($_REQUEST['session']), true);

    if(isset($response['access_token'])) {
        $this->api->setAccessToken($response['access_token']);
        $_SESSION['access_token'] = $this->api->getAccessToken();
    }

}
elseif(isset($_SESSION['access_token']) && ! isset($_REQUEST['signed_request'])) 
    $this->api->setAccessToken($_SESSION['access_token']);
elseif(isset($_REQUEST['signed_request'])) {
    Session::invalidate('fbuser');
    $_SESSION['access_token'] = '';
}

Here is how I handle the user data:

try {
    $this->user = Session::getVar('fbuser');
    if ($this->user === false || is_null($this->user)) {
        $facebookUser = $this->api->api('me?fields=id,name,first_name,last_name');
        $this->user = new FBUserModel(array('fbId' => $facebookUser['fbId'], ...));
        Session::setVar('fbuser', $this->user);
    }
}

The Problem

Everything looks fine while testing. Only once an error occured: the first time after permission was set. Now, since the app is online, it seems as if the error occurs on average with every second user in

$facebookUser = $this->api->api('me?fields=id,name,first_name,last_name');

with the error:

An active access token must be used to query information about the current user.

Question

So why is this happening? It is very hard to debug since the error seems to only occur when a user enters the app the first time, after the app authentication and the access token has changed. And even that is not happening every time. How should I handle the session and access token right with the new PHP SDK?

Any help would be highly appreciatied!

Edit

I found out that there are some IE issues with cookies/session inside an iFrame. As seen in this blog post. With that hint and some further research I added the following lines in my bootstrap:

ini_set('session.use_trans_sid', 1);
header('P3P:CP="IDC DSP COR ADM DEVi TAIi PSA PSD IVAi IVDi CONi HIS OUR IND CNT"');

Now its much better, but the information from about 2 of 50 users get lost between the steps landing page (authentication) -> formular -> and registration. So there is still something I missed.

Edit 2

I edited my user handling from

if ($this->user === false || is_null($this->user)) {
    // get user data
}

to

if ((is_object($this->user) && $this->user->fbId == '') || $this->user === false || is_null($this->user)) {
    // get user data
}

This seems to help a little bit. I think the main problem is somewhere in my session.

Furthermore I added a try/catch block to see if somewhere in my app a Facebook OAuthException is thrown. If this is the case, I redirect the top location to the Facebook Page and Tab to get a new signed request. Though this might help solve this problem, I want to prevent my app from having to redirect the user.

Edit 3

After some days of intense debugging and logging I found out, that the $_REQUEST['session'] coming from the FB.ui permissions.request method is empty infrequently.

Here is how I handle it:

This is the stuff I always included:

FB.provide("UIServer.Methods", {'permissions.request': {size : {width: 575, height: 300}, url: 'connect/uiserver.php', transform : FB.UIServer.genericTransform}});

And this function is called on form submit. Always worked for me, but somehow it still sends the form although session == ''.

function getPermission(form) {

    session = $('#' + $(form).attr('id') + ' input[name="session"]');

    if($(session).val() != '') {
        form.submit();
        return;
    }

    FB.ui({method: "permissions.request", "perms": 'user_photos'}, function callback(info){
        if(info.status=='connected' && info.session !== null) {
            $(session).val(JSON.stringify(info.session));
            form.submit();
        }
    });
    return;
}

Answer 1

My solution

Well, since everything I did was just a workaround until the new JS SDK comes out, there seems to be no best practice. Setting session.use_trans_sid to 1 and adding the P3P header helped to overcome IE iFrame cookie issues (see my first edit). After a few days of heavy debugging I found out, that FB.ui’s permission_request does not send a new access token everytime (<5%).

If this happens, something went wrong. But this little something is driving me crazy. Since this happens infrequently, I can bear redirecting users back to the facebook tab to get a new signed request. With the new JS SDK, hopefully, this won’t happen anymore.

Update: final solution

There was one little thing I have overseen and the solution can be found here: FB is not defined problem
I did not load the JS SDK asynchronously! This explains everything. Sometimes the all.js file was not loaded fast enough, so there was a JS error. Due to that, neither the permission dialog nor the JS validation worked and an empty #session input value was sent.