Symfony form Diff Data

diff_form.php

<?php
$data = $request->request->all();

print("REQUEST DATA<br/>");
foreach ($data as $k => $d) {
    print("$k: <pre>"); print_r($d); print("</pre>");
}

$children = $form->all();

print("<br/>FORM CHILDREN<br/>");
foreach ($children as $ch) {
    print($ch->getName() . "<br/>");
}

$data = array_diff_key($data, $children);
//$data contains now extra fields

print("<br/>DIFF DATA<br/>");
foreach ($data as $k => $d) {
    print("$k: <pre>"); print_r($d); print("</pre>");
}
die;