php dom Xml loop throught elements preserve childrens - php

Question

So i have an Xml file like
<cars>
<id>1</id>
<photos>
<img>http://sit.com/img.jpg</img>
<img>http://sit.com/img.jpg</img>
<img>http://sit.com/img.jpg</img>
<img>http://sit.com/img.jpg</img>
</photos>
</cars>
So i need to change all tag name to alternative and i need get something like
<cars>
<ex_id>1</ex_id>
<images>
<photo>http://sit.com/img.jpg</photo>
<photo>http://sit.com/img.jpg</photo>
<photo>http://sit.com/img.jpg</photo>
<photo>http://sit.com/img.jpg</photo>
</images>
</cars>
My code is
foreach ($dom->getElementsByTagName('cars') as $item) {
for ($i = 0; $i < $item->childNodes->length; ++$i) {
$car = $item->childNodes->item($i);
$NewElement = $dom->createElement($newName,$value);
$car->parentNode->replaceChild($NewElement->cloneNode(TRUE), $car);
}
}
Do something like that
<cars>
<ex_id>1</ex_id>
<images/>
</cars>
So it cut all childrens of <photos>, so my question is how to preserve children and also change childrens tags from <img> to <photo>

Answer 1

Here are several issues:
getElementByTagName() and $childNodes return 'live' lists, they change if you change the DOM. You can use iterator_to_array() to copy them into an array.
Here are not only element nodes. Comments, cdata sections and text (even containing only whitespaces) are nodes, too. If you iterate $childNodes you will have to validate the DOMNode::$nodeType.
Do not use the second argument of DOMDocument::createElement(). It has a broken escaping. Create a text node and append it.
1 and 2 go away if you use Xpath to fetch the nodes.
$dom = new DOMDocument();
$dom->loadXml($xml);
$xpath = new DOMXPath($dom);
foreach ($xpath->evaluate('/cars/images/img') as $photo) {
$newNode = $dom->createElement('photo');
$newNode->appendChild($dom->createTextNode($photo->textContent));
$photo->parentNode->replaceChild($newNode, $photo);
}
echo $dom->saveXml();
Output:
<?xml version="1.0"?>
<cars>
<ex_id>1</ex_id>
<images>
<photo>http://sit.com/img.jpg</photo>
<photo>http://sit.com/img.jpg</photo>
<photo>http://sit.com/img.jpg</photo>
<photo>http://sit.com/img.jpg</photo>
</images>
</cars>
Changing an DOM document is often a bad idea. It is easier to extract data from a source document and build a new target document:
$source = new DOMDocument();
$source->loadXml($xml);
$xpath = new DOMXPath($source);
$target = new DOMDocument();
$target->formatOutput = TRUE;
$cars = $target->appendChild($target->createElement('cars'));
$cars
->appendChild($target->createElement('ex_id'))
->appendChild(
$target->createTextNode(
$xpath->evaluate('string(/cars/id)')
)
);
$images = $cars->appendChild($target->createElement('images'));
foreach ($xpath->evaluate('/cars/photos/img') as $photo) {
$images
->appendChild($target->createElement('photo'))
->appendChild($target->createTextNode($photo->textContent));
}
echo $target->saveXml();
Output:
<?xml version="1.0"?>
<cars>
<ex_id>1</ex_id>
<images>
<photo>http://sit.com/img.jpg</photo>
<photo>http://sit.com/img.jpg</photo>
<photo>http://sit.com/img.jpg</photo>
<photo>http://sit.com/img.jpg</photo>
</images>
</cars>
Here is a language dedicated to transforming XML - XSLT. XSLT is supported by PHPs ext/xsl.