PHP - Extract a chunk of XML from a larger XML document

Question

I asked a similar question last week but did not get an answer that really nailed it. I suspect the question needs to be stated more plainly so here goes:

Given this XML:

<?xml version="1.0" encoding="utf-8"?>
<everyone>
  <guest>
    <name>Joseph Needham</name>
    <age>53</age>
  </guest>
  <guest>
    <name>Lu Gwei-djen</name>
    <age>31</age>
  </guest>
</everyone>

How do I return precisely this:

  <guest>
    <name>Joseph Needham</name>
    <age>53</age>
  </guest>
  <guest>
    <name>Lu Gwei-djen</name>
    <age>31</age>
  </guest>

I don't want a simplexml object, I don't want to convert anything, I don't want just the values of nodes, I don't want a new XML document with its corresponding header... just that chunk of XML. Can't use external libraries... nothing that doesn't come with a standard, average PHP install. How do I extract one out of the other?

My best guess? Use DomDocument to get the nodes names and content somehow and then rebuild what I want by using a foreach loop and echoing out the various node names and values including line endings to format everything properly. However, this seems like it could be amazingly clunky. I suspect there is a simpler way to do it so I want to see if anyone here on stackoverflow know what that way is (or can tell me that there is, in fact, NOT an easier way). Thanks in advance.

Answer 1

preg_match('`<guest>.*</guest>`is', $xml, $matches);
print_r($matches);

Answer 2

$reader = new XMLReader();
$reader->xml($xml_str);
$reader->read();
$inner = $reader->readInnerXML();

// $inner is your desired xml string.

One advantage of using XMLReader is that it uses less memory than SimpleXML or the DOM classes. Another is that it's very fast.

Answer 3

$string = <<<XML
<?xml version="1.0" encoding="utf-8"?>
<everyone>
  <guest>
    <name>Joseph Needham</name>
    <age>53</age>
  </guest>
  <guest>
    <name>Lu Gwei-djen</name>
    <age>31</age>
  </guest>
</everyone>

XML;

$xml = new SimpleXMLElement($string);
$nodes = $xml->xpath('/everyone/guest');

$result = '';
foreach ( $nodes as $node ) {
  $result .= $node->asXML()."\n";
}
echo $result;
die;

Answer 4

Something like this (using XPath - if you have another way to get a list of the guest elements, you can use that) should do the trick.

$xml = '';
$xpath = new DOMXPath($document);
foreach($xpath->query('//everyone/guest') as $guestNode) {
    $xml .= $document->saveXML($guestNode);
}