Codeigniter - agregar filtro por un campo a getallrecord

$condition	=	'';

if(isset($_REQUEST['username']) and $_REQUEST['username']!=""){

    $condition	.=	' AND username LIKE "%'.$_REQUEST['username'].'%" ';

}

if(isset($_REQUEST['useremail']) and $_REQUEST['useremail']!=""){

    $condition	.=	' AND useremail LIKE "%'.$_REQUEST['useremail'].'%" ';

}

if(isset($_REQUEST['fechafact']) and $_REQUEST['fechafact']!=""){

    $condition	.=	' AND fechafact LIKE "%'.$_REQUEST['fechafact'].'%" ';

}

if(isset($_REQUEST['montofact']) and $_REQUEST['montofact']!=""){

    $condition	.=	' AND montofact LIKE "%'.$_REQUEST['montofact'].'%" ';

}

if(isset($_REQUEST['df']) and $_REQUEST['df']!=""){

    $condition	.=	' AND DATE(dt)>="'.$_REQUEST['df'].'" ';

}

if(isset($_REQUEST['dt']) and $_REQUEST['dt']!=""){

    $condition	.=	' AND DATE(dt)<="'.$_REQUEST['dt'].'" ';

}

// $this->db-> like ('nombre', 'pedro'); esto me funcionó pero despues me dio errpr o filtre por la sesion  $_SESSION['username']

$userData	=	$db->getAllRecords('users','*'  ,$condition,'ORDER BY id DESC');

// Crea un objeto de consulta

$query = $this->db->table('users');

// Define las condiciones de filtro

if (isset($_REQUEST['username']) && $_REQUEST['username'] != "") {

    $query->like('username', '%' . $_REQUEST['username'] . '%');

}

if (isset($_REQUEST['useremail']) && $_REQUEST['useremail'] != "") {

    $query->like('useremail', '%' . $_REQUEST['useremail'] . '%');

}

if (isset($_REQUEST['fechafact']) && $_REQUEST['fechafact'] != "") {

    $query->like('fechafact', '%' . $_REQUEST['fechafact'] . '%');

}

if (isset($_REQUEST['montofact']) && $_REQUEST['montofact'] != "") {

    $query->like('montofact', '%' . $_REQUEST['montofact'] . '%');

}

if (isset($_REQUEST['df']) && $_REQUEST['df'] != "") {

    $query->where('dt >=', $_REQUEST['df']);

}

if (isset($_REQUEST['dt']) && $_REQUEST['dt'] != "") {

    $query->where('dt <=', $_REQUEST['dt']);

}

// Ejecuta la consulta

$userData = $query->get()->getResult();