我怎么知道我的应用程序正在Facebook内运行

Question

If I have an app and it is run inside facebook. the first load I will get the

$_REQUEST['signed_request'] 

but if you click on any link inside my app and navigate within the app you will lose that $_REQUEST['signed_request'] .

Is there any other way to know if my app is being run in a browser or inside facebook?

Answer 1

You can continue to pass the signed_request around. Within your app, all your links should end with ?signed_request=<whatever> (or &signed_request=<whatever> if there is already a query string), and all your POST forms should include signed_request as a hidden input. Then you will always have access to signed_request .

Answer 2

You can save value of signed_request in php session , something like this:

session_start();
if (isset($_REQUEST['signed_request'])){
  $_SESSION['signed_request'] = $_REQUEST['signed_request'];
}

Later you can check if signed_request value is saved in session:

if (isset($_SESSION['signed_request'])){
  //do something
}

Answer 3

If you really only need to know whether your app is being accessed through Facebook, the simplest way is to use a unique url in your app settings -- either a unique hostname like fb.yoursite.com, or a unique directory name like www.yoursite.com/fbapp/ . Then you configure your server so the unique hostname/directory points the same place as the regular hostname/directory. That way the same files can be reached either way, but your scripts can check the $_SERVER info to tell whether it's a Facebook request.

HOWEVER...unless you are strictly dealing with non-authorized access, you have to consider whether that will really solve anything. If you have to "detect" things like this, you must not be carrying any persistent state info, and your user will lose his "identity" as soon as he goes to page 2. So most likely, what you need to be considering is not a way to tell on each page whether the user is in Facebook, but rather a way to parse all the info you need on the first page and then make that available in all other pages. Many people use PHP sessions for this. Personally I think that's a bad idea, and would do something more like what Ben suggested in his answer (using GET and POST to pass the info you need).

Answer 4

Personally, a very simple yet effective solution I've used is some client side javascript (which can obviously be disabled etc) - this works nicely for a simple redirect and it won't work in every case.

// Redirect if the page is not an iframe
if (window.location == window.parent.location){
    window.top.location = '{{ facebook_tab_url }}';
};