Question

I’ve got a URL that I’m wanting to replace values if they’re there, but add if they’re not.

My URL would be for example: http://www.example.com/online/admin/users?p=Name&sort=user&dir=desc and I want to write a script that will write out the queries in the URL again if it exists already or add it if it doesn’t. I want to the write it to an “a” tag but with the different value I select for sort and dir

I found some code at a website called Add Querystring Variable

function add_querystring_var($url, $key, $value) {
    $url = preg_replace('/(.*)(?|&)' . $key . '=[^&]+?(&)(.*)/i', '$1$2$4', $url . '&');
    $url = substr($url, 0, -1);
    if (strpos($url, '?') === false) {
        return ($url . '?' . $key . '=' . $value);
    } else {
        return ($url . '&' . $key . '=' . $value);
    }
}

My only problem is I’m not sure how to use it to do what I want.

This is the code I’ve got so far to go with it

add_querystring_var("http://".$_SERVER['HTTP_HOST'].$_SERVER['REQUEST_URI'],"sort","lvl");
add_querystring_var("http://".$_SERVER['HTTP_HOST'].$_SERVER['REQUEST_URI'],"dir","asc");

But I don’t know what to do from here as that isn’t writing anything out for me.

I know it will be simple but I’m new to this area of PHP. 😀

EDIT

Code so far

$url='http://'.$_SERVER['HTTP_HOST'].$_SERVER['REQUEST_URI'];
function add_querystring_var($url, $key, $value) {
    $urlarray = parse_url($url);
    parse_str($urlarray['query'],$queryarray);
    $queryarray[$key]=$value;
    $queryarray = http_build_query($queryarray);
    return http_build_url($url,array('query'=>$queryarray),HTTP_URL_JOIN_QUERY);
}
$url_id=add_querystring_var($url,"sort","lvl");
$url_id=add_querystring_var($url,"dir",$dir);

<?php echo '<a href="'.$url.'">New Anchor</a>'; ?>

But this returned blank. Any more ideas at all? Thanks for all the input so far guys.

Answer 1

I would recommend to use parse_url and parse_str

function add_querystring_var($url, $key, $value) {
    $urlarray = explode('?',$url);
    $query = '';
    if(isset($urlarray[1]))
        $query = $urlarray[1];
    parse_str($query,$queryarray);
    $queryarray[$key]=$value;
    $queryarray = http_build_query($queryarray);

    return $urlarray[0].'?'.$queryarray;
}

call like this

add_querystring_var("http://".$_SERVER['HTTP_HOST'].$_SERVER['REQUEST_URI'],'sort','id');

or for your specific case

<?php 
$url='http://'.$_SERVER['HTTP_HOST'].$_SERVER['REQUEST_URI'];
$url=add_querystring_var($url,"sort","lvl");
$url=add_querystring_var($url,"dir", $dir);
echo '<a href="'.$url.'">New Anchor</a>'; 
?>

Tested