PestXML.php

<?php
/**
 * Pest is a REST client for PHP.
 * PestXML adds XML-specific functionality to Pest, automatically converting
 * XML data resturned from REST services into SimpleXML objects.
 *
 * In other words, while Pest's get/post/put/delete calls return raw strings,
 * PestXML's return SimpleXML objects.
 *
 * PestXML also attempts to derive error messages from the body of erroneous
 * responses, expecting that these too are in XML (i.e. the contents of
 * the first <error></error> tag in the response is assumed to be the error mssage)
 *
 * See http://github.com/educoder/pest for details.
 *
 * This code is licensed for use, modification, and distribution
 * under the terms of the MIT License (see http://en.wikipedia.org/wiki/MIT_License)
 */

require_once 'Pest.php';

class PestXML extends Pest
{
    /**
     * Process error
     * @param string $body
     * @return string
     */
    public function processError($body)
    {
        try {
            $xml = $this->processBody($body);
            if (!$xml)
                return $body;

            $error = $xml->xpath('//error');

            if ($error && $error[0])
                return strval($error[0]);
            else
                return $body;
        } catch (PestXML_Exception $e) {
            return $body;
        }
    }

    /**
     * Process body
     *
     * @todo This should always return a SimpleXMLElement
     * @param string $body
     * @return null|SimpleXMLElement|string
     * @throws PestXML_Exception
     */
    public function processBody($body)
    {
        libxml_use_internal_errors(true);
        if (empty($body) || preg_match('/^\s+$/', $body))
            return null;

        $xml = simplexml_load_string($body);

        if (!$xml) {
            $err = "Couldn't parse XML response because:\n";
            $xml_errors = libxml_get_errors();
            libxml_clear_errors();
            if (!empty($xml_errors)) {
                foreach ($xml_errors as $xml_err)
                    $err .= "\n    - " . $xml_err->message;
                $err .= "\nThe response was:\n";
                $err .= $body;
                throw new PestXML_Exception($err);
            }
        }

        return $xml;
    }
}

class PestXML_Exception extends Pest_Exception
{}