How to work with $_SERVER['QUERY_STRING']

Question

How to work with $_SERVER['QUERY_STRING'] and pagination?

When my table is sorted by this link:

<a href="'.$_SERVER['PHP_SELF'].'?sort_name=name&sort=asc" title="'.$lang['sorteer_asc'].'"></a>

My url becomes: relation.php?sort_name=adres&sort=asc

The I use an pagination link:

echo '<a href="'.$_SERVER['PHP_SELF'].'?'.$_SERVER['QUERY_STRING'].'&page='.$i.'">'.$i.'</a> '; 

And the url becomes: relation.php?sort_name=adres&sort=asc&page=2

So far so good but when browsing to other pages it can be as long as: relation.php?sort_name=adres&sort=asc&page=2&page=3&page=14&page=23&page=27

The age keeps appearing because of the $_SERVER['QUERY_STRING'], how can I clean up my url with only keeping the last page and ?sort_name=adres&sort=asc.

Or do you suggest an other solution of ordering and pagination?

Answer 1

Instead of reusing QUERY_STRING, you should assemble it anew with http_build_query().

// Merge $_GET with new parameter
$QS = http_build_query(array_merge($_GET, array("page"=>2)));

// You should apply htmlspecialchars() on the path prior outputting:
echo "<a href='" . htmlspecialchars("$_SERVER[PHP_SELF]?$QS") . "'> $i </a>";

Thus you have all current $_GET parameters included, but can add or replace entries with new values. And it's ensured that each appears only once.