用XML创建子元素

Question

I am trying to accomplish the following:

<?xml version="1.0"?>
<books>
<book>
<name>Harry potter</name>
<category>Adventure | Family | Fantasy</category>
<pages>850</pages>
<author>
<author_name>Jhon Doe</author_name>
<author_wiki>http://wikipedia....</author_wiki>
</author>
<description>lorem ipsum blabla</description>
</book>
</books>

The part i cant get to work is de author element in between. But i cant go futher then is, ive tried a lot of things but it seems to only give me blanco pages. What i have now:

<?xml version="1.0"?>
<books>
<book>
<name>Harry potter</name>
<category>Adventure | Family | Fantasy</category>
<pages>850</pages>
<description>lorem ipsum blabla</description>
</book>
</books>

<?php header('Content-Type: text/xml;'); 
// Start XML file, create parent node
$doc = new DOMDocument('1.0');
$root = $doc->createElement('books');
$root = $doc->appendChild($root);
// we want a nice output
$doc->formatOutput = true;
$user = $doc->createElement('book');
$user = $doc->appendChild($user);
$title = $doc->createElement('name');
$title = $user->appendChild($title);
$text = $doc->createTextNode('Harry potter');
$text = $title->appendChild($text);
$title = $doc->createElement('category');
$title = $user->appendChild($title);
$text = $doc->createTextNode('Adventure | Family | Fantasy');
$text = $title->appendChild($text);
$title = $doc->createElement('pages');
$title = $user->appendChild($title);
$text = $doc->createTextNode('850');
$text = $title->appendChild($text);
$title = $doc->createElement('description');
$title = $user->appendChild($title);
$text = $doc->createTextNode('lorem ipsum blabla');
$text = $title->appendChild($text);
$user = $root->appendChild($user);
echo $doc->saveXML();
?>

Answer 1

What you need to do here, is append the author details to the author element and not the root element. So something like this would work:

header('Content-Type: text/xml;'); 
$doc = new DOMDocument('1.0');
$doc->formatOutput = true;

$book = $doc->createElement("book");
$doc->appendChild($book);

$author = $doc->createElement("author");
$book->appendChild($author); // add author as child of book

// you can add content at the same time as creating the element
$author_name = $doc->createElement("author_name", "John Doe");
// append author name to author element
$author->appendChild($author_name); 

echo $doc->saveXML();

Also note that you can save some space creating text nodes by adding the text inside createElement, though that may not suffice in cetain circumstances as the value is not escaped (ref: php.net - I just used it here for quickness).

Sample output:

<book>
  <author>
    <author_name>John Doe</author_name>
  </author>
</book>