How to fetch exact parameter from XML string with PHP? - php

Question

This is part of XML document:
<entry>
<author>
<name>Dunnock_D</name>
<uri>http://www.flickr.com/people/dunnock_d/</uri>
</author>
<link rel="license" type="text/html" href="https://creativecommons.org/licenses/by-nc/2.0/deed.en" />
<link rel="enclosure" type="image/jpeg" href="http://farm8.staticflickr.com/7548/26820724620_1d221c3187_b.jpg" />
</entry>
My code:
$xml = simplexml_load_string($result);
foreach ($xml->entry as $pixinfo) {
echo $pixinfo->link[1]['href'];
}
The problem is there can be one or more link strings and I need only particular with rel="enclosure" attribute.
What is the easiest way without extra IF and loops?
Thank you!

Answer 1

For that you can use DOMXPath, more specifically the query function. Let's say your $result variable contains the following:
<?xml version='1.0' encoding='UTF-8'?>
<entries>
<entry>
<author>
<name>Dunnock_D</name>
<uri>http://www.flickr.com/people/dunnock_d/</uri>
</author>
<link rel="license" type="text/html" href="https://creativecommons.org/licenses/by-nc/2.0/deed.en" />
<link rel="enclosure" type="image/jpeg" href="http://farm8.staticflickr.com/7548/26820724620_1d221c3187_b.jpg" />
</entry>
<entry>
<author>
<name>Dunnock_D</name>
<uri>http://www.flickr.com/people/dunnock_d/</uri>
</author>
<link rel="license" type="text/html" href="https://creativecommons.org/licenses/by-nc/2.0/deed.en" />
<link rel="enclosure" type="image/jpeg" href="http://farm8.staticflickr.com/7548/26820724620_1d221c3187_b.jpg" />
</entry>
<entry>
<author>
<name>Dunnock_D</name>
<uri>http://www.flickr.com/people/dunnock_d/</uri>
</author>
<link rel="license" type="text/html" href="https://creativecommons.org/licenses/by-nc/2.0/deed.en" />
<link rel="enclosure" type="image/jpeg" href="http://farm8.staticflickr.com/7548/26820724620_1d221c3187_b.jpg" />
</entry>
</entries>
I know the entries are repeated, but it's only for demo purposes. The code to get only the enclosure links would be:
$doc = new DOMDocument();
$doc->preserveWhiteSpace = false;
$doc->loadXML($result);
$xpath = new DOMXpath($doc);
$entries = $xpath->query('//entries/entry');
foreach ($entries as $entry) {
$link = $xpath->query('link[#rel="enclosure"]', $entry)->item(0);
$href = $link->getAttribute('href');
echo "{$href}\n";
}

Answer 2

You are using simplexml. Just use "attributes()" function: http://php.net/manual/pt_BR/simplexmlelement.attributes.php
Or you can access directly:
foreach ($xml->entry as $pixinfo) {
if($pixinfo->link[1]['rel'] == 'enclosure') {
echo $pixinfo->link[1]['href'];
}
}

Answer 3

The solution is Xpath.
With SimpleXML you can fetch the attribute node and cast the generated SimpleXMLElement into a string. You should make sure that you got an element before you cast it. SimpleXMLElement::xpath() will always return an array of SimpleXMLElement objects.
$entry = new SimpleXMLElement($xml);
$enclosures = $entry->xpath('link[#rel="enclosure"]/#href');
if (count($enclosures) > 0) {
var_dump((string)$enclosures[0]);
}
Output:
string(63) "http://farm8.staticflickr.com/7548/26820724620_1d221c3187_b.jpg"
With DOM the bootstrap is slightly larger, but you can fetch the href attribute directly as a string:
$document = new DOMDocument();
$document->loadXml($xml);
$xpath = new DOMXpath($document);
var_dump(
$xpath->evaluate('string(/entry/link[#rel="enclosure"]/#href)')
);
This will return an empty string if the expression does not match.