Clear session variable after use

Question

Is it possible to use a session variable, then unset it directly after?

Example:

//====
//Process Form
if ($_POST['Submit']) {
    $update = $userSettings->update($_POST);

    //If there are form errors
 if (!$update) {
        //Load the errors into an array
        $errors = $update[1];
    } else {
        //Set the session
        $_SESSION['showUpdated'] = true;

        //Redirect to this page
        header("Location: http://www.mysite.com/settings");
    }
}

//==================

if ($_SESSION['showUpdated']) {
 echo "Settings Updated";
    unset($_SESSION['showUpdated'];
}

So after the form is submitted, if there are no errors:

• Set a session to say the form submission was okay
• Reload the page (to prevent re-submitted POST data)
• If the 'showUpdated' session variable is set, display the "Updated" message
• Unset the session variable (so we don't see the message on next reload)

Currently the problem is, if you unset the session variable straight after; It is as if you have un-set it before the "if exists" part.

Any solutions? Is this even the best way to do it?

Many thanks!

Answer 1

I noticed a small error in the original example that might cause other problems.

unset($_SESSION['showUpdated'];

needs to be

unset($_SESSION['showUpdated']);

Not including that end ) in the unset will cause an error.

Answer 2

That looks like it should work. Make sure you call session_start() before trying to use the session, and always exit() or die() after a redirect header.

I accomplish what you're doing a little differently. I keep a 'message' element in the session. I'll stick text in like 'Your data was saved', error messages, etc. Then, on each page (actually in a page template class), I check to see if the $_SESSION['message'] is set and not empty. If there's something there, I display the message and set the value to an empty string or null.