$d = explode(".",$request->get("due_date",".."));
foreach ($d as $key => $val) $d[$key]=(int)$val;

if (
	!is_numeric($d[0]) || $d[0]<1 ||$d[0]>31 ||
	!is_numeric($d[1]) || $d[1]<1 ||$d[1]>12 ||
	!is_numeric($d[2]) || $d[2]<2005 ||$d[2]>2100 ) {
    $error["due_date"] = "Missing date.";
}