php XML DOM - updating XML dom elements - php

Question

I have an XML that looks like this:
<nitf:body.content>
<nitf:block>
<nitf:p style="#style1">Contents of paragraph1.</nitf:p>
<nitf:p style="#style2">Contents of paragraph2.</nitf:p>
<nitf:p style="#style1"><nitf:em class="#bold">This is bold</nitf:em> This is not bold</nitf:p>
<nitf:p style="#style1"><nitf:em class="#italic">This is italic</nitf:em> This is not italic</nitf:p>
</nitf:block>
</nitf:body.content>
And I made a loop to update the text of all nitf:em tags as following:
foreach($this->doc->getElementsByTagNameNS($this->nitfNS, 'em') as $em) {
$class = $em->getAttribute('class');
if ($class == '#italic') {
$em->nodeValue = '<i>' . $em->nodeValue . '</i>';
}
elseif (strpos($class, 'bold') !== FALSE) {
$em->nodeValue = '<b>' . $em->nodeValue . '</b>';
}
$this->doc->saveXML($em);
}
Now when I loop again through the paragraph elements, the paragraphs that should be updated by the previous loop are all empty.
foreach ($this->doc->getElementsByTagNameNS($this->nitfNS, 'p') as $element) {
$textnode = $element->childNodes->item(0);
$txt = $textnode->wholeText; // this is EMPTY now
}
I read somewhere that"<>" characters might mess up the DOM parser. If that is the case here how can I update the em elements with the desired html tags (italic & bold).
Thanks in advance

Answer 1

You have made 2 mistakes. One is the property $textnode->wholeText - it does not exists. If you like to fetch the text content use $textnode->textContent.
The other mistake is setting DOMElement::$nodeValue with some XML fragment. That will not work. The property does contain only text, not the tags. In fact you should never set it to anything else then an empty string (to delete all child nodes). The escaping is broken.
For your problem create a new node, move all child nodes from the em to it and append the new node back to the em.
$document = new DOMDocument();
$document->loadXml($xml);
foreach($document->getElementsByTagNameNS($nitfNS, 'em') as $em) {
$class = $em->getAttribute('class');
$newNode = FALSE;
if ($class == '#italic') {
$newNode = $document->createElement('i');
} elseif (strpos($class, 'bold') !== FALSE) {
$newNode = $document->createElement('b');
}
if ($newNode) {
while ($em->firstChild) {
$newNode->appendChild($em->firstChild);
}
$em->appendChild($newNode);
}
echo $document->saveXML($em), "\n\n";
}
Output:
<nitf:em class="#bold"><b>This is bold</b></nitf:em>
<nitf:em class="#italic"><i>This is italic</i></nitf:em>