[SOLVED] Plugin Help Trying to update "unpub_date" with a tv value.

<?php //<-only there to allow syntax highlighting

$tvValue = $modx->getTemplateVarOutput(array("event_date"), $published='1');
$id = $modx->documentIdentifier;
$unpub_date = $tvValue['event_date'];
$table = $modx->getFullTableName('site_content');
$e = &$modx->Event;
switch ($e->name) {
    case "OnDocFormSave":
        $result = $modx->db->update('unpub_date = "' . $unpub_date . '"', $table, 'id = "' . $id . '"');
        break;
    default :
        return; // stop here - this is very important.
        break;
}
?>

<?php //<-Only here for syntax highlighting
print_r($_POST);  
$tvValue = $modx->getTemplateVarOutput(array("event_date"), $published='1');
$unpub_date = $tvValue['event_date'];
$e = &$modx->Event;
switch ($e->name) {
    case "OnBeforeDocFormSave":
        $_POST['unpub_date'] = $unpub_date; 
        break;
    default :
        return; // stop here - this is very important.
        break;
}

if (empty ($unpub_date)) {
	$unpub_date = 0;
} else {
	list ($d, $m, $Y, $H, $M, $S) = sscanf($unpub_date, "%2d-%2d-%4d %2d:%2d:%2d");
	$unpub_date = mktime($H, $M, $S, $m, $d, $Y);
	if ($unpub_date < $currentdate) {
		$published = 0;
	}
}