Convert XML elements into text nodes including attribute values

xmlToTextWihtAttr.php

<?php

$data = <<<XML
<?xml version="1.0" encoding="ISO-8859-1"?>
<element>
  <title>ein Titel</title>
  <content>Ein Inhalt</content>
  <content>
    Ein Inhalt mit
    <subcontent att1="Hallo">Subnodes</subcontent> und weiterem Text,
    der <subcontent att1="Hallo" att2="Welt" > weitere Subnodes enthalten</subcontent>
    kann
  </content>
</element>
XML;

$dom = new DOMDocument();
$dom->loadXml($data);
$xpath = new DOMXpath($dom);

// let's look for all subcontent elements in all or no namespaces
foreach ($xpath->evaluate('//*[local-name() = "subcontent"]') as $contentNode) {
  $text = '';
  // all attribute values to a string
  foreach ($contentNode->attributes as $attribute) {
    $text .= $attribute->value.' ';
  }
  // add the text content of the node
  $text .= $contentNode->textContent;
  // and create a text node from that string
  $textNode = $dom->createTextNode($text);
  //replace the element with the new text node
  $contentNode->parentNode->replaceChild(
    $textNode, $contentNode
  );
}

header('Content-type: text/xml');
echo $dom->saveXml();