Adding a block of XML as child of a SimpleXMLElement object - php

Question

I have this SimpleXMLElement object with a XML setup similar to the following...
$xml = <<<EOX
<books>
<book>
<name>ABCD</name>
</book>
</books>
EOX;
$sx = new SimpleXMLElement( $xml );
Now I have a class named Book that contains info. about each book. The same class can also spit out the book info. in XML format akin the the above (the nested block).. example,
$book = new Book( 'EFGH' );
$book->genXML();
... will generate
<book>
<name>EFGH</name>
</book>
Now I'm trying to figure out a way by which I can use this generated XML block and append as a child of so that now it looks like... for example..
// Non-existent member method. For illustration purposes only.
$sx->addXMLChild( $book->genXML() );
...XML tree now looks like:
<books>
<book>
<name>ABCD</name>
</book>
<book>
<name>EFGH</name>
</book>
</books>
From what documentation I have read on SimpleXMLElement, addChild() won't get this done for you as it doesn't support XML data as tag value.

Answer 1

Two solutions. First, you do it with the help of libxml / DOMDocument / SimpleXML: you have to import your $sx object to DOM, create a DOMDocumentFragment and use DOMDocumentFragment::appendXML():
$doc = dom_import_simplexml($sx)->ownerDocument;
$fragment = $doc->createDocumentFragment();
$fragment->appendXML($book->genXML());
$doc->documentElement->appendChild($fragment);
// your original $sx is now already modified.
See the Online Demo.
You can also extend from SimpleXMLElement and add a method that is providing this. Using this specialized object then would allow you to create the following easily:
$sx = new MySimpleXMLElement($xml);
$sx->addXML($book->genXML());
Another solution is to use an XML library that already has this feature built-in like SimpleDOM. You grab SimpleDOM and you use insertXML(), which works like the addXMLChild() method you were describing.
include 'SimpleDOM.php';
$books = simpledom_load_string(
'<books>
<book>
<name>ABCD</name>
</book>
</books>'
);
$books->insertXML(
'<book>
<name>EFGH</name>
</book>'
);

Answer 2

Have a look at my code:
$doc = new DOMDocument();
$doc->loadXML("<root/>");
$fragment = $doc->createDocumentFragment();
$fragment->appendXML("<foo>text</foo><bar>text2</bar>");
$doc->documentElement->appendChild($fragment);
echo $doc->saveXML();
This modifies the XML document by adding an XML fragment. Online Demo.