Problems with creating XML with DOMDocument in PHP

Question

The below code is fetched from php.net (http://docs.php.net/manual/en/domdocument.savexml.php). My problem is - it doesn't work. My only output from this is: "Saving all the document: Saving only the title part:". What am I missing here?

$doc = new DOMDocument('1.0'); // we want a nice output
$doc->formatOutput = true;
$root = $doc->createElement('book'); $root = $doc->appendChild($root);
$title = $doc->createElement('title');
$title = $root->appendChild($title); $text = $doc->createTextNode('This is the title');
$text = $title->appendChild($text); echo "Saving all the document:\n";
echo $doc->saveXML() . "\n"; echo "Saving only the title part:\n";
echo $doc->saveXML($title);

Answer 1

There are tags in the output generated from saveXML(), and the browser tries to interpret those.

If you use the following portion of code :

$doc = new DOMDocument('1.0'); // we want a nice output
$doc->formatOutput = true;
$root = $doc->createElement('book');
$root = $doc->appendChild($root);
$title = $doc->createElement('title');
$title = $root->appendChild($title);
$text = $doc->createTextNode('This is the title');
$text = $title->appendChild($text);
echo $doc->saveXML();

Then, the browser doesn't display a thing, as tags are interpreted.

But, if you replace the last one by this one :

echo '<pre>' .htmlspecialchars($doc->saveXML()) . '</pre>';

Then, you'll se the ouput :

<?xml version="1.0"?>
<book>
  <title>This is the title</title>
</book>

This is because the tags are escaped, now -- and, so, not interpreted.

Another solution would be to :

• Keep the first portion of code
• But use View Source in your browser, instead of just looking at the rendered page.

Answer 2

PHP sends a Content-type http header. And by default it's text/html. I.e. the client is supposed to interpret the response document as html. But you're sending an xml document (and some text and another fragment, which invalidates the output).
If you want to send an xml document tell the client so, e.g. via header('Content-type: text/xml')

$doc = new DOMDocument('1.0');
$doc->formatOutput = true;

$root = $doc->appendChild($doc->createElement('book'));
$title = $root->appendChild($doc->createElement('title', 'This is the title'));

if (headers_sent() ) {
  echo 'oh oh, something wnet wrong';
}
else {
  header('Content-type: text/xml; charset=utf-8');
  echo $doc->saveXML();
}