How to dynamically update a sitemap with php? - php

Question

I have a dynamic site where posts are constantly being generated i have it coded so each time a new post is added it appends the site map url entry to the bottom of the sitemap.xml file.
$lastID = $db->lastInsertId();
$file = 'sitemap.xml';
$current = file_get_contents($file);
$current .= "<url>
<loc>http://website.net/viewpost.php?ID=".$lastID."</loc>
<changefreq>monthly</changefreq>
</url>";
file_put_contents($file, $current);
this works but the closing tag in the xml file urlset needs to be at the end of the file. So when i append this data it goes after the urlset and even if i added this to the string there would be multiple closing tags for this. How do i update the file so it doesnt go after the closing tag.
Regenerating the entire site map every time would work but it seems like a lot of work as there are almost 100 pages as of right now and it will need to query multiple tables to get the data

Answer 1

This is a simple function for inserting an element before,after or inside another element.
<?php
public function myInsertNode($newNode, $refNode, $insertMode=null) {
if(!$insertMode || $insertMode == "inside") {
$refNode->appendChild($newNode);
} else if($insertMode == "before") {
$refNode->parentNode->insertBefore($newNode, $refNode);
} else if($insertMode == "after") {
if($refNode->nextSibling) {
$refNode->parentNode->insertBefore($newNode, $refNode->nextSibling);
} else {
$refNode->parentNode->appendChild($newNode);
}
}
}
?>