Php How do you redirect without copying the same url query

Question

I am validating a form on a page and I need to redirect back to the same page with the same url query and a additional &valid=false at the end of the query when redirected.

How would you do this so that the url is not repeated on redirect:

http://test.com/index.php?a=1&b=2&valid=false&a=1&b=2&valid=false

I am using $_SERVER['REQUEST_URI']

Answer 1

There are many ways to do it, here is a simple one:

$url = $_SERVER['REQUEST_URI'];
if (!isset($_GET['valid'])) {
    $url.='&valid=false';    //assuming there are always additional parameters, otherwise you must check whether to use '?' or '&' 
}

But you can also use parse_url(), strpos(), regular expressions etc

Answer 2

You can use of http_build_query() after modifying parameters:

<?php
    $_GET['a'] = 1;
    $_GET['b'] = 2;
    $_GET['valid'] = 'true';

    $url = $_SERVER['SCRIPT_NAME'].'?'.http_build_query($_GET);
?>

Like that, if $_GET['valid'] is not defined then it will be created, else it will be modified.