How to check if a user likes my Facebook Page or URL using Facebook's API

Question

I think I'm going crazy. I can't get it to work.
I simply want to check if a user has liked my page with javascript in an iFrame app.

FB.api({
    method:     "pages.isFan",
    page_id:        my_page_id,
},  function(response) {
        console.log(response);
        if(response){
            alert('You Likey');
        } else {
            alert('You not Likey :(');
        }
    }
);

This returns: False
But I'm a fan of my page so shouldn't it return true?!

Answer 1

I tore my hair out over this one too. Your code only works if the user has granted an extended permission for that which is not ideal.

Here's another approach.

In a nutshell, if you turn on the OAuth 2.0 for Canvas advanced option, Facebook will send a $_REQUEST['signed_request'] along with every page requested within your tab app. If you parse that signed_request you can get some info about the user including if they've liked the page or not.

function parsePageSignedRequest() {
    if (isset($_REQUEST['signed_request'])) {
      $encoded_sig = null;
      $payload = null;
      list($encoded_sig, $payload) = explode('.', $_REQUEST['signed_request'], 2);
      $sig = base64_decode(strtr($encoded_sig, '-_', '+/'));
      $data = json_decode(base64_decode(strtr($payload, '-_', '+/'), true));
      return $data;
    }
    return false;
  }
  if($signed_request = parsePageSignedRequest()) {
    if($signed_request->page->liked) {
      echo "This content is for Fans only!";
    } else {
      echo "Please click on the Like button to view this tab!";
    }
  }

Answer 2

You can use (PHP)

$isFan = file_get_contents("https://api.facebook.com/method/pages.isFan?format=json&access_token=" . USER_TOKEN . "&page_id=" . FB_FANPAGE_ID);

That will return one of three:

• string true string false json
• formatted response of error if token
• or page_id are not valid

I guess the only not-using-token way to achieve this is with the signed_request Jason Siffring just posted. My helper using PHP SDK:

function isFan(){
    global $facebook;
    $request = $facebook->getSignedRequest();
    return $request['page']['liked'];
}