Facebook PHP API giving inconsistent results when used inside <div> - php

Question

I am working with both the Facebook PHP SDK and the Facebook JS SDK (using the JS SDK to handle login only, much as is discussed here: https://developers.facebook.com/blog/post/534/).
I have a custom button that I have created and attached to the FB.login() function. My goal is to have the text inside that button say "Log in with Facebook" if the user is not logged in, and to the text inside the button display the user's name if they are logged in.
The problem is that when I try to refer to the $user_profile variable that has the logged in user's information, it works when I use it outside the button, but says that the variable is not set when it is used inside the button (code below). What could be causing this?
<?php
// Get the contents of static-head.html to open the HTML doc:
readfile("static-head.html");
// Include the Facebook PHP SDK so that we can have people login
require_once('fb/facebook.php');
$config = array(
'appId' => 'MY_APP_ID',
'secret' => 'MY_APP_SECRET',
'allowSignedRequest' => false
);
$facebook = new Facebook($config);
$user_id = $facebook->getUser();
// Get Facebook Login information
if($user_id) {
// We have a user ID, so probably a logged in user.
// If not, we'll get an exception, which we handle below.
try {
$user_profile = $facebook->api('/me','GET');
// If this doesn't throw an error, we now we have a $user_profile that we can use
} catch(FacebookApiException $e) {
// If the user is logged out, you can have a user ID even though the access token is invalid.
// In this case, we'll get an exception, so we'll just wait for the user to log in.
error_log($e->getType());
error_log($e->getMessage());
// Set the $user_id to NULL so that there's no confusion elsewhere in the app.
$user_id = NULL;
}
} else {
// Let the user log in through the JavaScript SDK
}
// Just to prove that $user_profile is being recognized:
// ***This works! It returns "Chris"
echo $user_profile['first_name'];
// Function to set the text inside the LogIn/LogOut button:
// ***This doesn't work! It returns "Log in with Facebook"
function getLogInLogOutText(){
if(isset($user_profile)){
return $user_profile['first_name'];
} else{
return 'Log in with Facebook';
}
}
?>
<div id="userLogInLogOut" class="uiControlsDivs">
<button id="userLogInLogOutButton"><?php echo getLogInLogOutText(); ?></button>
</div>
I am utterly confused how this is possible. On one line, the code works and returns the Facebook user's name. Then, just a few lines later, it doesn't work! What is going on?!
Thanks for any help you might be able to provide!

Answer 1

Try parsing the variable to the function, so say make the function:
function getLogInOutText() { ...
into
function getLogInOutText($user_profile) { ...
and call with with that, i.e. :
<?php echo getLogInOutText($user_profile); ?>
Not sure it will work, but it's worth a test. Otherwise try making it a global variable:
PHP reference for variables scope - http://www.php.net/manual/en/language.variables.scope.php