Why don't I see the request variable I set in the first script?

Question

As I try to retrieve the variable status from the $_REQUEST[] array I set in the first script (and then do a redirect), I see nothing but a warning Undefined index: status. Why is that ?

<?php
        $_REQUEST['status'] = "success";
        $rd_header = "location: action_script.php";
        header($rd_header);
?>

action script.php

<?php
echo "Unpacking the request variable : {$_REQUEST['status']}";

Because in your header statement you are not passing any parameters... It's a fresh URL with a clean `$_REQUEST` variable. — Lix, Mar 17 '13 at 16:41
If you put a banknote into one pocket, does it surprise you if you cannot find it in another? — Your Common Sense, Mar 17 '13 at 16:43
@Lix how to send a parameter with the header function ? http://php.net/manual/en/function.header.php I don't see it in the doc — saplingPro, Mar 17 '13 at 16:44
@YourCommonSense yeah it will ! I often forget which pocket I put the banknote into — saplingPro, Mar 17 '13 at 16:45

score 4 · Answer 1 · answered Mar 17 '13 at 16:41

4

What you're looking for is sessions:

<?php
    session_start();
    $_SESSION['status'] = "success";
    $rd_header = "location: action_script.php";
    header($rd_header);
?>

<?php
    session_start();
    echo "Unpacking the request variable : {$_SESSION['status']}";

Note the addition of session_start() at the top of both pages. As you'll read in the link I posted this is required and must be on all pages you wish to use sessions.

answered Mar 17 '13 at 16:41

John Conde

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no not a session..But sending the parameter as a request variable – saplingPro Mar 17 '13 at 16:43

score 4 · Accepted Answer · answered Mar 17 '13 at 16:46

It is because your header() statement redirects the user to a brand new URL. Any $_GET or $_POST parameters are no longer there because we are no longer on the same page.

You have a few options.

1- Firstly you can use $_SESSION to persist data across page redirection.

session_start();
$_SESSIONJ['data'] = $data; 
// this variable is now held in the session and can be accessed as long as there is a valid session.

2- Append some get parameters to your URL when redirecting -

$rd_header = "location: action_script.php?param1=foo&param2=bar";
header($rd_header);
// now you'll have the parameter `param1` and `param2` once the user has been redirected.

For the second method, this documentation might be usefull. It is a method to create a query string from an array called http_build_query().

Don't forget to use the correct encoding with `http_build_query`: for GET, this is RFC 3986. — Marcel Korpel, Mar 17 '13 at 16:49

score 2 · Answer 3 · answered Mar 17 '13 at 16:46

2

What you are looking for is probably sending a GET parameter:

$rd_header = "Location: action_script.php?status=success";
header($rd_header);

that can be retrieved in the action_script.php via:

$_GET['status'];

You don't really need sessions or cookies in this case but you have to consider the fact that a GET post can be easily edited by the user.

answered Mar 17 '13 at 16:46

Shoe

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2

+1 For mentioning the problem of "trusting" the data in a `$_GET` request. **Never trust those users!** ;) – Lix Mar 17 '13 at 16:52

Why don't I see the request variable I set in the first script?

3 Answers3