php; remove single variable value pair from querystring

Question

I have a page that lists out items according to numerous parameters ie variables with values.

listitems.php?color=green&size=small&cat=pants&pa         


        

Answer 1

Another solution, to avoid & problems too!!!

remove_query('http://example.com/?a=valueWith**&**inside&b=value');

Code:

function remove_query($url, $which_argument=false){ 
    return preg_replace('/'. ($which_argument ? '(\&|)'.$which_argument.'(\=(.*?)((?=&(?!amp\;))|$)|(.*?)\b)' : '(\?.*)').'/i' , '', $url);  
}

Answer 2

It wouldn't work if edit=1 is the first variable:

listitems.php?edit=1&color=green&...

You can use the $_GET variable to create the query string yourself. Something like:

$qs = '';
foreach ($_GET as $key => $value){
    if ($key  == 'pagenum'){
        // Replace page number
        $qs .= $key  . '=' . $new_page_num . '&';
    }elseif ($key  != 'edit'){
        // Keep all key/values, except 'edit'
        $qs .= $key  . '=' . urlencode($value) . '&';
    }
}

Answer 3

I'd use http_build_query, which nicely accepts an array of parameters and formats it correctly. You'd be able to unset the edit parameter from $_GET and push the rest of it into this function.

Note that your code has a missing call to htmlspecialchars(). A URL can contain characters that are active in HTML. So when outputting it into a link: Escape!

Some example:

unset($_GET['edit']); // delete edit parameter;
$_GET['pagenum'] = 5; // change page number
$qs = http_build_query($_GET);

... output link here.

Answer 4

Here's my shot:

/**
*   Receives a URL string and a query string to remove. Returns URL without the query string
*/
function remove_url_query($url, $key) {
    $url = preg_replace('/(?:&|(\?))' . $key . '=[^&]*(?(1)&|)?/i', "$1", $url);
    $url = rtrim($url, '?');
    $url = rtrim($url, '&');
    return $url;
}

Returns:

remove_url_query('http://example.com?a', 'a') => http://example.com
remove_url_query('http://example.com?a=1', 'a') => http:/example.com
remove_url_query('http://example.com?a=1&b=2', 'a') => http://example.com?b=2

Kudos to David Walsh.