JSON TO XML via POST request

json2xml.php

<?php
$json_post = $_REQUEST['json'];

function json_validate($string)
{
    // decode the JSON data
    $result = json_decode($string);

    // switch and check possible JSON errors
    switch (json_last_error()) {
        case JSON_ERROR_NONE:
            $error = ''; // JSON is valid // No error has occurred
            break;
        case JSON_ERROR_DEPTH:
            $error = 'The maximum stack depth has been exceeded.';
            break;
        case JSON_ERROR_STATE_MISMATCH:
            $error = 'Invalid or malformed JSON.';
            break;
        case JSON_ERROR_CTRL_CHAR:
            $error = 'Control character error, possibly incorrectly encoded.';
            break;
        case JSON_ERROR_SYNTAX:
            $error = 'Syntax error, malformed JSON.';
            break;
        // PHP >= 5.3.3
        case JSON_ERROR_UTF8:
            $error = 'Malformed UTF-8 characters, possibly incorrectly encoded.';
            break;
        // PHP >= 5.5.0
        case JSON_ERROR_RECURSION:
            $error = 'One or more recursive references in the value to be encoded.';
            break;
        // PHP >= 5.5.0
        case JSON_ERROR_INF_OR_NAN:
            $error = 'One or more NAN or INF values in the value to be encoded.';
            break;
        case JSON_ERROR_UNSUPPORTED_TYPE:
            $error = 'A value of a type that cannot be encoded was given.';
            break;
        default:
            $error = 'Unknown JSON error occured.';
            break;
    }

    if ($error !== '') {
        // throw the Exception or exit // or whatever :)
		$arr = array("error" => "true","reason" => $error );
		
        $errormsg = json_encode($arr);
		return $errormsg;
		
    }

    // everything is OK
    return $result;
}


/**
 * Convert JSON to XML
 * @param string    - json
 * @return string   - XML
 */
function json_to_xml($json)
{
    include_once("XML/Serializer.php");

    $options = array (
      'addDecl' => TRUE,
      'encoding' => 'UTF-8',
      'indent' => '  ',
      'rootName' => 'json',
      'mode' => 'simplexml'
    );

    $serializer = new XML_Serializer($options);
    $obj = json_decode($json);
    if ($serializer->serialize($obj)) {
        return $serializer->getSerializedData();
    } else {
        return null;
    }
}

$result = json_validate($json_post);
echo json_to_xml($result);
?>

requires pear package installed XML_Serializer