Hvordan skaber jeg denne json i PHP ?

Kode 

<?php
/*
  {"emails":[{"group":"Idag","list":[{"id":1,"subject":"test","to":["test"],"body":"test","time":"test","datetime":"test","from":"test2","dp":"asds","dpRetina":"ads"}]}]}
  {"emails":[{"group":"Idag","list":[{"id":1,"subject":"test","to":["test"],"body":"test","time":"test","datetime":"test","from":"test2","dp":"asds","dpRetina":"ads"}]}]}
 */
$ar = array(
    "emails" => array(
        array(
            "group" => "Idag",
            "list" => array(
                array(
                    "id" => 1,
                    "subject" => "test",
                    "to" => array("test"),
                    "body" => "test",
                    "time" => "test",
                    "datetime" => "test",
                    "from" => "test2",
                    "dp" => "asds",
                    "dpRetina" => "ads"
                ),
            ),
        ),
    )
);

echo json_encode($ar);
?>

( Evt. data udfra Mysql data )

Kode 

$str = '{"emails":[{"group":"Idag","list":[{"id":1,"subject":"test","to":["test"],"body":"test","time":"test","datetime":"test","from":"test2","dp":"asds","dpRetina":"ads"}]}]}';
print_r( json_decode($str));

Kode 

--
-- Database: `test`
--

-- --------------------------------------------------------

--
-- Struktur-dump for tabellen `tbl_newsletter`
--

CREATE TABLE IF NOT EXISTS `tbl_newsletter` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `subject` varchar(255) COLLATE utf8_danish_ci NOT NULL,
  `body` text COLLATE utf8_danish_ci NOT NULL,
  `time` varchar(255) COLLATE utf8_danish_ci NOT NULL COMMENT 'bør have datatypen  time',
  `datetime` varchar(255) COLLATE utf8_danish_ci NOT NULL COMMENT 'bør have datatypen  datetime',
  `n_from` varchar(255) COLLATE utf8_danish_ci NOT NULL COMMENT 'from er et reseveret ord i sql',
  `dp` varchar(255) COLLATE utf8_danish_ci NOT NULL,
  `dpRetina` varchar(255) COLLATE utf8_danish_ci NOT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB  DEFAULT CHARSET=utf8 COLLATE=utf8_danish_ci AUTO_INCREMENT=2 ;

--
-- Data dump for tabellen `tbl_newsletter`
--

INSERT INTO `tbl_newsletter` (`id`, `subject`, `body`, `time`, `datetime`, `n_from`, `dp`, `dpRetina`) VALUES
(1, 'test', 'test', 'test', 'test', 'test2', 'asds', 'ads');

-- --------------------------------------------------------

--
-- Struktur-dump for tabellen `tbl_user`
--

CREATE TABLE IF NOT EXISTS `tbl_user` (
  `id` int(10) NOT NULL,
  `firstname` varchar(255) COLLATE utf8_danish_ci DEFAULT NULL,
  `lastname` varchar(255) COLLATE utf8_danish_ci DEFAULT NULL,
  `email` varchar(255) COLLATE utf8_danish_ci DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_danish_ci;

--
-- Data dump for tabellen `tbl_user`
--

INSERT INTO `tbl_user` (`id`, `firstname`, `lastname`, `email`) VALUES
(2, 'Ronny', 'Olsen', 'udvikleren@olsensweb.dk'),
(21, 'Rip', 'And', 'rip@andeby.dk'),
(22, 'Rap', 'And', 'rap@andeby.dk'),
(23, 'Rup', 'And', 'rup@andeby.dk');

Kode 

<?php
$to = array();
$mail_list = array();
$conn = new PDO("mysql:host=localhost;dbname=test;charset=utf8", "root", "");


$sql = "SELECT * FROM tbl_user";
$rs = $conn->query($sql) or die(var_export($conn->errorinfo(), TRUE));
while ($obj = $rs->fetch(PDO::FETCH_OBJ)) {
    $to[] = $obj->firstname . " " . $obj->lastname . " <" . $obj->email . ">";
}
// print_r($to);
// $to=  array("test");

$sql = "SELECT * FROM tbl_newsletter where id =1";
$rs = $conn->query($sql) or die(var_export($conn->errorinfo(), TRUE));
$obj = $rs->fetch(PDO::FETCH_OBJ);

// hvis jeg ikke typecaster id vil det komme ud som en string
$mail_list = array(
    "id" => (int) $obj->id,
    "subject" => $obj->subject,
    "to" => $to,
    "body" => $obj->body,
    "time" => $obj->time,
    "datetime" => $obj->datetime,
    "from" => $obj->n_from,
    "dp" => $obj->dp,
    "dpRetina" => $obj->dpRetina
);

// var_dump($mail_list);

$ar = array(
    "emails" => array(
        array(
            "group" => "Idag",
            "list" => array($mail_list),
        ),
    )
);
echo json_encode($ar);
?>