Does "header()" php function unset global variables?

Question

I am developing a php script which contains an html form.

If not all fields are filled in the correct way the script will signal an error and redirect back to the same page with the header function setting an error variable to yes with the get method:

header("Location: registration_page.php?error_empty=yes");

my script has an error handling part in which it highlights the fields containing a mistake, but I would like to keep the value of the fields correctly filled.

I am implementing this feature as I found in this other question:

How can I keep a value in a text input after a submit occurs?

but the problem is that when the page reopens the forms will not contain the old values.

My question is: does anybody know if the header function unsets global variables in the $_REQUEST array?

And do you know what kind of solution could I adopt?Maybe sessions?

Thanks in advance,

Matteo!

Answer 1

$_COOKIES will stay set, but $_POST & $_GET will be destroyed, as the client is moving to a new page. If they need to be retained, they must first be stored into $_SESSION before calling the redirect.

session_start();
$_SESSION['last_post'] = $_POST;
header("Location: http://example.com");
exit();

// On the redirected page, use the stored POST values and unset them in $_SESSION
session_start();
if (empty($_POST) && isset($_SESSION['last_post'])) {
  $post = $_SESSION['last_post'];
  unset($_SESSION['last_post']);
}
else $post = $_POST;