PHP - SimpleXML - AddChild with another SimpleXMLElement - php

Question

I'm trying to build a rather complex XML document.
I have a bunch of sections of the XML document that repeats. I thought I'd use multiple string templates as base document for the sections and create instances of XML elements using simplexml_load_string.
So I have one instance of SimpleXMLElement as the base document
$root =
simplexml_load_string($template_root);
then I loop through some items in my database, create new SimpleXMLElement, something like this:
for (bla bla bla):
$item = simplexml_load_string($template_item);
// do stuff with item
// try to add item to the root document..
// Stuck here.. can't do $root->items->addChild($item)
endfor;
I can't call addChild because it just expects a tag name and value.. you can't addChild another SimpleXMLElement.
Am I missing something here? seems really dumb that addChild can't take a SimpleXMLELement as a parameter.
Is there any other way to do this? (apart from using a different xml lib)

Answer 1

As far as I know, you can't do it with SimpleXML because addChild doesn't make a deep copy of the element (being necessary to specify the tag name can easily be overcome by calling SimpleXMLElement::getName()).
One solution would be to use DOM instead:
With this function:
function sxml_append(SimpleXMLElement $to, SimpleXMLElement $from) {
$toDom = dom_import_simplexml($to);
$fromDom = dom_import_simplexml($from);
$toDom->appendChild($toDom->ownerDocument->importNode($fromDom, true));
}
We have for
<?php
header("Content-type: text/plain");
$sxml = simplexml_load_string("<root></root>");
$n1 = simplexml_load_string("<child>one</child>");
$n2 = simplexml_load_string("<child><k>two</k></child>");
sxml_append($sxml, $n1);
sxml_append($sxml, $n2);
echo $sxml->asXML();
the output
<?xml version="1.0"?>
<root><child>one</child><child><k>two</k></child></root>
See also some user comments that use recursive functions and addChild, e.g. this one.

Answer 2

You could use this function that is based in creating the children with attributes from the source:
function xml_adopt($root, $new) {
$node = $root->addChild($new->getName(), (string) $new);
foreach($new->attributes() as $attr => $value) {
$node->addAttribute($attr, $value);
}
foreach($new->children() as $ch) {
xml_adopt($node, $ch);
}
}
$xml = new SimpleXMLElement("<root/>");
$child = new SimpleXMLElement("<content><p a=\"aaaaaaa\">a paragraph</p><p>another <br/>p</p></content>");
xml_adopt($xml, $child);
echo $xml->asXML()."\n";
This will produce:
<?xml version="1.0"?>
<root><content><p a="aaaaaaa">a paragraph</p><p>another p<br/></p></content></root>

Answer 3

The xml_adopt() example doesn't preserve namespace nodes.
My edit was rejected because it changed to much? was spam?.
Here is a version of xml_adopt() that preserves namespaces.
function xml_adopt($root, $new, $namespace = null) {
// first add the new node
// NOTE: addChild does NOT escape "&" ampersands in (string)$new !!!
// replace them or use htmlspecialchars(). see addchild docs comments.
$node = $root->addChild($new->getName(), (string) $new, $namespace);
// add any attributes for the new node
foreach($new->attributes() as $attr => $value) {
$node->addAttribute($attr, $value);
}
// get all namespaces, include a blank one
$namespaces = array_merge(array(null), $new->getNameSpaces(true));
// add any child nodes, including optional namespace
foreach($namespaces as $space) {
foreach ($new->children($space) as $child) {
xml_adopt($node, $child, $space);
}
}
}
(edit: example added)
$xml = new SimpleXMLElement(
'<?xml version="1.0" encoding="utf-8"?>
<rss version="2.0" xmlns:media="http://search.yahoo.com/mrss/">
<channel></channel></rss>');
$item = new SimpleXMLElement(
'<item xmlns:media="http://search.yahoo.com/mrss/">
<title>Slide Title</title>
<description>Some description</description>
<link>http://example.com/img/image.jpg</link>
<guid isPermaLink="false">A1234</guid>
<media:content url="http://example.com/img/image.jpg" medium="image" duration="15">
</media:content>
</item>');
$channel = $xml->channel;
xml_adopt($channel, $item);
// output:
// Note that the namespace is (correctly) only preserved on the root element
'<?xml version="1.0" encoding="utf-8"?>
<rss xmlns:media="http://search.yahoo.com/mrss/" version="2.0">
<channel>
<item>
<title>Slide Title</title>
<description>Some description</description>
<link>http://example.com/img/image.jpg</link>
<guid isPermaLink="false">A1234</guid>
<media:content url="http://example.com/img/image.jpg" medium="image" duration="15">
</media:content>
</item>
</channel>
</rss>'