Using SimpleXML to create an XML object from scratch

Question

Is it possible to use PHP's SimpleXML functions to create an XML object from scratch? Looking through the function list, there's ways to import an existing XML string into an object that you can then manipulate, but if I just want to generate an XML object programmatically from scratch, what's the best way to do that?

I figured out that you can use simplexml_load_string() and pass in the root string that you want, and then you've got an object you can manipulate by adding children... although this seems like kind of a hack, since I have to actually hardcode some XML into the string before it can be loaded.

I've done it using the DOMDocument functions, although it's a little confusing because I'm not sure what the DOM has to do with creating a pure XML document... so maybe it's just badly named :-)

Answer 1

My answer is no because the constructor for SimpleXMLElement() cannot take 0 arguments or a zero-length string. I am not going to test this right now but you can have this:

try { $obj = @new SimpleXMLElement($xml); } catch (Exception $e) { die('failure to parse xml.'); }

Answer 2

Sure you can. Eg.

<?php
$newsXML = new SimpleXMLElement("<news></news>");
$newsXML->addAttribute('newsPagePrefix', 'value goes here');
$newsIntro = $newsXML->addChild('content');
$newsIntro->addAttribute('type', 'latest');
Header('Content-type: text/xml');
echo $newsXML->asXML();
?>

Output

<?xml version="1.0"?>
<news newsPagePrefix="value goes here"><content type="latest"/></news>

Have fun.

Answer 3

In PHP5, you should use the Document Object Model class instead. Example:

$domDoc = new DOMDocument;
$rootElt = $domDoc->createElement('root');
$rootNode = $domDoc->appendChild($rootElt);

$subElt = $domDoc->createElement('foo');
    $attr = $domDoc->createAttribute('ah');
    $attrVal = $domDoc->createTextNode('OK');
    $attr->appendChild($attrVal);
    $subElt->appendChild($attr);
$subNode = $rootNode->appendChild($subElt);

$textNode = $domDoc->createTextNode('Wow, it works!');
$subNode->appendChild($textNode);

echo htmlentities($domDoc->saveXML());

Answer 4

Please see my answer here. As dreamwerx.myopenid.com points out, it is possible to do this with SimpleXML, but the DOM extension would be the better and more flexible way. Additionally there is a third way: using XMLWriter. It's much more simple to use than the DOM and therefore it's my preferred way of writing XML documents from scratch.

$w=new XMLWriter();
$w->openMemory();
$w->startDocument('1.0','UTF-8');
$w->startElement("root");
    $w->writeAttribute("ah", "OK");
    $w->text('Wow, it works!');
$w->endElement();
echo htmlentities($w->outputMemory(true));

By the way: DOM stands for Document Object Model; this is the standardized API into XML documents.

Answer 5

Of course, the officially accepted method would be to use the SimpleDOMXmlCartoonWriter package and just discard the cartoon. Doesn't anyone just answer the frickin' question? Sheesh.