PHP/MySQL Contact Data List Restful API

include_once('../../inc/dbconnect.inc.php');

$rawData = file_get_contents("php://input");
$mainArray = json_decode($rawData);

foreach ($mainArray as $key => $val) {
    "$key = $val";
}

//$id = $_POST['id'];

$fetch = "SELECT contactID,contactDate,phone,fullname,email,requestedService,hear FROM ads_contact WHERE contactID='$val'";
$fetchQuery = mysqli_query($mysqli, $fetch);
$arr = array();
$data = $fetchQuery->fetch_assoc();
$arr[] = $data;

// Values
echo $json_response = json_encode($arr);