getting xml node with php - php

Question

Im attempting to echo/assign a variable to the contents of the node "code" which is inside status;
I can get request-id just fine...
Any ideas people?
<?
$responseXML = '<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<payment xmlns="http://www.example.com" self="http://www.example.com">
<merchant-account-id ref="http://www.example.com">0000</merchant-account-id>
<transaction-id>0000</transaction-id>
<request-id>0000</request-id>
<transaction-type>auth</transaction-type>
<transaction-state>success</transaction-state>
<completion-time-stamp>2015-12-28T17:39:25.000Z</completion-time-stamp>
<statuses>
<status code="201.0000" description="3d-acquirer:The resource was successfully created." severity="information"/>
</statuses>
<avs-code>P</avs-code>
<requested-amount currency="GBP">0.01</requested-amount>
<account-holder>
<first-name>test</first-name>
<last-name>test</last-name>
<email>test.test#hotmail.co.uk</email>
<phone>00000000000</phone>
<address>
<street1>test</street1>
<city>test test</city>
<state>test</state>
<country>GB</country>
</address>
</account-holder>
<card-token>
<token-id>000</token-id>
<masked-account-number>000000******0000</masked-account-number>
</card-token>
<ip-address>192.168.0.1</ip-address>
<descriptor></descriptor>
<authorization-code>000000</authorization-code>
<api-id>000-000</api-id>
</payment>';
$doc = new DOMDocument;
$doc->loadXML($responseXML);
echo $doc->getElementsByTagName('request-id')->item(0)->nodeValue;
echo $doc->getElementsByTagName('status code')->item(0)->nodeValue;
?>
I've tried simplexml looad string, but pulling hair out with this one, can anybody shed some light, speed of getting this info out in one process is quite important so not to stress the webserver out!
Many thanks.

Answer 1

Using DOM is a good idea, but the API methods are a little cumbersome. Using Xpath makes it a lot easier.
Xpath allows you to use expressions to fetch node lists or scalar values from a DOM:
$document = new DOMDocument;
$document->loadXML($responseXML);
$xpath = new DOMXpath($document);
$xpath->registerNamespace('example', 'http://www.example.com');
echo $xpath->evaluate('string(//example:request-id)'), "\n";
echo $xpath->evaluate('string(//example:status/#code)');
Output:
0000
201.0000
Xpath does not have a default namespace so if you XML has a namespace (like your example) you need to register a prefix for it and use it.

Answer 2

As code is an attribute of xml tag status, doing
getElementsByTagName('status code')
is wrong.
There's a special method for getting attribute value getAttribute:
echo $doc->getElementsByTagName('status')->item(0)->getAttribute('code');

Answer 3

Using XPath allows to access the status node very precisely.
DOMDocument + XPath:
$responseXML = '...';
$doc = new DOMDocument();
$doc->loadXML($responseXML);
$xp = new DOMXpath($doc);
$xp->registerNamespace('example', 'http://www.example.com');
// Every status node.
$statusNodes = $xp->query('//example:status');
// or a very specific one.
$statusNodes = $xp->query('/example:payment/example:statuses/example:status');
$statusNode = $statusNodes[0];
$code = $statusNode->getAttribute('code');
// $code is '201.0000'.
// To change the 'code' value.
$statusNode->setAttribute('code', '302.0000');