^^&&^^

Edit File: serializeNullProperties.php

<?PHP
/**
 * This example demonstrates the use of
 * ignoreNull => true
 *
 * It can be used to serialize an indexed array
 * like ext/simplexml does, by using the name
 * of the parent tag, while omitting this tag.
 *
 * @author Stephan Schmidt <schst@php.net>
 */
error_reporting(E_ALL);

require_once 'XML/Serializer.php';

$options = array(
                    "indent"         => '    ',
                    "linebreak"      => "\n",
                );

$serializer = new XML_Serializer($options);

$object = new stdClass();
$object->foo = 'bar';
$object->bar = null;

$array = array(
                'foo' => 'bar',
                'bar' => null
            );

$result = $serializer->serialize($object);

if ($result === true) {
    echo "<pre>";
    echo htmlentities($serializer->getSerializedData());
    echo "</pre>";
}

$result = $serializer->serialize($array);

if ($result === true) {
    echo "<pre>";
    echo htmlentities($serializer->getSerializedData());
    echo "</pre>";
}

$serializer->setOption('ignoreNull', true);
$result = $serializer->serialize($object);

if ($result === true) {
    echo "<pre>";
    echo htmlentities($serializer->getSerializedData());
    echo "</pre>";
}

$result = $serializer->serialize($array);

if ($result === true) {
    echo "<pre>";
    echo htmlentities($serializer->getSerializedData());
    echo "</pre>";
}
?>