PHP会话变量未继承

Question

I have a controller/controller.php file that starts a session and sets some session variables. I then 'include' a model/model.php file and call a function to load it.

When I try and use the session variables from the controller.php file in the model.php file, I am getting many: Undefined variable: _SESSION errors.

Here is an example of setting a session variable in the controller.php file:

$_SESSION['userName'] = 'some data'

In the model.php file I am trying to retrieve it by this code:

print($_SESSION['userName']);

What am I doing wrong?

EDIT

my controller.php file code:

<?PHP

session_start();

if (isset($_POST['Login'])) {

$_SESSION['pointsForQuestion'] = '1';
$_SESSION['userName'] = $_POST['txtUsername'];

if(!is_file($_SESSION['userName'].".txt"))
{
    writeUserDetails($_SESSION['userName'],"1","0");
    $_SESSION['currentLevel'] = "1";
    $_SESSION['score'] = "0";
} else {
    readUserDetails($_SESSION['userName']);
}

print('logged in');

include('../model/model.php');
print page_load();

}   

function writeUserDetails($username,$level,$score) {
    $fh = fopen($username.".txt", 'w') or die("can't open file");
    fwrite($fh, $level.",".$score);
    fclose($fh);
}

function readUserDetails($username) {
    $userDetails = explode(',', file_get_contents($username.".txt"));
    $_SESSION['currentLevel'] = $userDetails[0];
    $_SESSION['score'] = $userDetails[1];
}


?>

Answer 1

Start your session before defining the session variables on top ie session_start();

Edited You have not set anything for these session variable that's why it is giving that error

$_SESSION['userName'];
$_SESSION['currentLevel'];
$_SESSION['score'];

You can delete these session variables if u dont want to set anything...

Answer 2

$_SESSION is a superglobal available in all scopes.

So, you must have forgotten session_start() .