SimpleXMLElement and xpath [duplicate] - php

Question

This question already has an answer here:
SimpleXmlElement and XPath, getting empty array()
(1 answer)
Closed 8 years ago.
I have an XML doc similar to:
<?xml version="1.0" encoding="UTF-8"?>
<entry xmlns="http://www.w3.org/2005/Atom" xmlns:zapi="http://zotero.org/ns/api">
<link rel="up" type="application/atom+xml" href="some link"/>
</entry>
I want the "up" (rel attribute) of the link element, so I do this:
$xml = new SimpleXMLElement($body);
$php_up = $xml->xpath("//link[#rel='up']");
var_dump($php_up); exit;
which just gives me array(0) { }.
What am I doing wrong?

Answer 1

The declaration in the second line of your XML gives two XML namespaces:
<entry xmlns="http://www.w3.org/2005/Atom" xmlns:zapi="http://zotero.org/ns/api">
The first xmlns attribute, with no colon-separated suffix, sets the "default" namespace for the entry element as being http://www.w3.org/2005/Atom, and descendant nodes with no prefix are in that namespace by default. To be able to access these elements with a "default" namespace using XPath, you need to set a namespace using registerXPathNamespace, and then perform your query, prefixing the element you're looking for (link) with the namespace:
$xml->registerXPathNamespace('d', 'http://www.w3.org/2005/Atom');
$php_up = $xml->xpath("//d:link[#rel='up']");
var_dump($php_up);
Output:
array(1) {
[0] =>
class SimpleXMLElement#2 (1) {
public $#attributes =>
array(3) {
'rel' =>
string(2) "up"
'type' =>
string(20) "application/atom+xml"
'href' =>
string(9) "some link"
}
}
}

Answer 2

You don't need XPATH to get the REL attribute. This should be as simple as:
$php_up = $xml->link->attributes()->rel;
Updated: To get the attributes of multiple link elements:
The XML:
<?xml version="1.0" encoding="UTF-8"?>
<entry xmlns="http://www.w3.org/2005/Atom" xmlns:zapi="http://zotero.org/ns/api">
<link rel="up" type="application/atom+xml" href="some link"/>
<link rel="down" type="application/atom+xml" href="some link"/>
</entry>
The PHP:
$xml = new SimpleXMLElement($body);
foreach ($xml->link as $link) {
$rels[] = (string)$link->attributes()->rel;
}
var_dump($rels); exit;

Answer 3

It's not going to be obvious, but you need to use str_replace on your xmlns :)
$body= str_replace('xmlns=', 'ns=', $body);
Before you call your $xml = new SimpleXMLElement($body);
Here's your eval.in