DOMDocument cannot change parentNode - php

Question

I cannot change the DOMDocument parentNode from null. I have tried using both appendChild and replaceChild, but haven't had any luck.
Where am I going wrong here?
error_reporting(E_ALL);
function xml_encode($mixed, $DOMDocument=null) {
if (is_null($DOMDocument)) {
$DOMDocument =new DOMDocument;
$DOMDocument->formatOutput = true;
xml_encode($mixed, $DOMDocument);
echo $DOMDocument->saveXML();
} else {
if (is_array($mixed)) {
$node = $DOMDocument->createElement('urlset', 'hello');
$DOMDocument->parentNode->appendChild($node);
}
}
}
$data = array();
for ($x = 0; $x <= 10; $x++) {
$data['urlset'][] = array(
'loc' => 'http://www.example.com/user',
'lastmod' => 'YYYY-MM-DD',
'changefreq' => 'monthly',
'priority' => 0.5
);
}
header('Content-Type: application/xml');
echo xml_encode($data);
?>
http://runnable.com/VWhQksAhdIJYEPLj/xml-encode-for-php

Answer 1

Since the document has no parent node you need to append the root node directly to the document, like this:
$DOMDocument->appendChild($node);
This works since DOMDocument extends DOMNode.
Working example:
error_reporting(E_ALL);
function xml_encode($mixed, &$DOMDocument=null) {
if (is_null($DOMDocument)) {
$DOMDocument =new DOMDocument;
$DOMDocument->formatOutput = true;
xml_encode($mixed, $DOMDocument);
return $DOMDocument->saveXML();
} else {
if (is_array($mixed)) {
$node = $DOMDocument->createElement('urlset', 'hello');
$DOMDocument->appendChild($node);
}
}
}
$data = array();
for ($x = 0; $x <= 10; $x++) {
$data['urlset'][] = array(
'loc' => 'http://www.example.com/user',
'lastmod' => 'YYYY-MM-DD',
'changefreq' => 'monthly',
'priority' => 0.5
);
}
header('Content-Type: application/xml');
echo xml_encode($data);
Btw, if you just want to serialize an XML file, DOM is a bit overhead. I would use a template engine for this, meaning handle it as plain text.

Answer 2

This should work, when you create a new DOMDocument you don't have a root element yet, so you can just create it and add it to the document
//You could add this to the top of xml_encode
if($DOMDocument->parentNode === null) {
$root = $DOMDocument->createElement('root');
$root = $DOMDocument->appendChild($root);
}
//Your script working:
<?php
error_reporting(E_ALL);
function xml_encode($mixed, $DOMDocument=null) {
if (is_null($DOMDocument)) {
$DOMDocument =new DOMDocument();
$DOMDocument->formatOutput = true;
//add here, but note that in the "else" it isn't sure if the DOMDocument has a root element
$root = $DOMDocument->createElement('root');
$root = $DOMDocument->appendChild($root);
xml_encode($mixed, $root);
echo $DOMDocument->saveXML();
} else {
if (is_array($mixed)) {
$node = $DOMDocument->createElement('urlset', 'hello');
$DOMDocument->parentNode->appendChild($node);
}
}
}
I'm not sure why you need the parentNode? you could do $DOMDocument->appendChild();