Modifying HTTP queries

talino

Hello.

I'm developing a site which has links for switching languages. The links reload the current page with ?land=fr or ?lang=en. These are stored in a session variable so that the query doesn't get appended every time.

This worked fine until I started adding pages with other HTTP queries. I was confronted with the problem of adding a parameter with a value to a URL which already has one or more ( with ? and & ). I wrote a function to solve this, and decided to make it more flexible so as to handle any query, not just the ?lang= one. The function expects

addQuery('lang','en')

It works but it seems so convoluted that I feel like I'm trying to reinvent the wheel:

function addQuery($param,$val) {
$uri = $_SERVER['REQUEST_URI'];
$query = $param."=".$val;
$prefix = (strpos($uri,"?")) ? "&" : "?";
$link = (strpos($uri,$param)) ? eregi_replace($param."=".$_GET[$param],$query,$uri) : $uri.$prefix.$query;
echo "<a href=\"$link\"></a>";
}

I don't have a lot of experience in PHP and I was wondering how other people were dealing with this problem. Is there a function which does this exact same thing?

Thanks.

Installer

parse_url() can probably be useful for you.

talino

Thank you for your quick reply. However, this can only reduce the size of my code without changing the fundamental problem (the 'query' key still contains all the different parts of the query, which can sometimes be totally unrelated). Thanks for the tip, though 🙂

Installer

You're right; parse_url() isn't much help. Here's how I'd do it:

$new_uri = addQuery('lang', 'en');
echo htmlentities($new_uri) . '<br />';

function addQuery($param, $val) { 
    $old_uri = $_SERVER['REQUEST_URI'];
    $lang_query = $param . '=' . $val;
    if ($_GET['lang']) {
        $return_uri = str_replace('lang=' . $_GET['lang'], $lang_query, $old_uri);
    } else {
        if (strpos($old_uri, '?')) {
            $return_uri = $old_uri . '&' . $lang_query;
        } else {
            $return_uri = $old_uri . '?' . $lang_query;
        }
    }
    return $return_uri;
}

I think it's less convoluted (meaning, to me, easier to read and maintain), but you may not.

hth

talino

Thank you for your reply, but I just had an idea: since the language parameter is the only session variable which is constant from page to page (for the time being), I simply wrote a new file called lang.php which takes care of everything in a very elegant manner (I think). It expects a simple link like <a href="lang.php?lang=en" and then does this:

session_start();
$_SESSION['lang'] = $_GET['lang'];
$page=$_SERVER['HTTP_REFERER'];
header("Location: $page");

It works just great. This way, no need to parse crazy links just to add another query. Don't know why I didn't think of this earlier. PHP really grows on you 🙂