PayrollReportController.php

<?php

function replacer($array) {
    $newArray = array();
    foreach ($array as $key=>$val) {
        if (preg_grep('/^$/', $val)) {
            $newArray[$key] = "empty";
        } else {
            $newArray[$key] = $val;
        }
    }

return $newArray;
}

$res = $this->replacer($res);