A problem of a repeated parameter in the pagination links?

Question

The problem is that when I load page 2 for example the URL becomes:

http://domain.com/index.php?restaurant-id=45¤tpage=2

And that\'s fine but when

Answer 1

You need to remove the previous value from the query string, e.g.:

preg_replace('/¤tpage=\\d+/', '', $_SERVER["QUERY_STRING"]);

instead of just $_SERVER["QUERY_STRING"].

I prefer to use a class like this to manipulate the query string:

final class QueryString
{
    private $data;

    private function __construct($start=null) {
        if ($start === null)
            $this->data = $_GET;
        elseif (!is_array($start))
            throw new InvalidArgumentException();
    }

    public function __isset($nm) {
        return isset($this->data[$nm]);
    }

    public function __unset($nm) {
        unset($this->data[$nm]);
    }

    public function __get($nm) {
        return isset($this->data[$nm])?$this->data[$nm]:"";
    }

    public function __set($nm, $val) {
        $this->data[$nm] = $val;
    }

    public function getString() {
        return $this->getStringInternal(false);
    }

    public function getStringHTML() {
        return $this->getStringInternal(true);
    }  

    public function __toString() {
        return $this->getString();
    }

    private function getStringInternal($HTML=false) {
        if (empty($this->data))
            return "";

        $res = "?";        
        foreach ($this->data as $k => $v) {
            if (!is_array($v)) {
                if ($v === "")
                    $res .= urlencode($k).'&';
                else
                    $res .= urlencode($k)."=".urlencode($v).'&';
            }
            else
                foreach ($v as $vv) {
                    $res .= urlencode($k)."[]=".urlencode($vv).'&';
                }
        }

        $res = substr($res,0,-1);
        if ($HTML)
            $res = htmlspecialchars($res);

        return $res;
    }
}

Then I can just do:

$qs = new QueryString();
$qs->currentpage = 7;
$url = "list.php" . $qs;

It will keep all the previous parameters, create "currentpage" if it doesn't exist and modify it if it exists.

Note: you can replace the loop of getStringInternal with http_build_query if you wish. I don't like the behavior of http_build_query when a key has several values; I prefer "a=1&a=2" to "a[0]=1&a[1]=2" and the original didn't add "[]" to the key; however PHP doesn't support multiple values without brackets in the key very well (I have to manualy parse the query string), Java web services I sometimes interface with do).