I am unable to echo my JSON encode object containing values - php

Question

I am writing a script the will a echo a json object with values from the datatable when a request is sent to that script with a particular id, I have been able to get the records of member in an array but when I encode it into a json it become empty automatically but when I serialize the object and echo I will get all my record. I want the response in JSON.
<?php
include '../classes/RegisteredMemberDAO.php';
if (isset($_GET['getMember'])) {
$members = RegisteredMemberDAO::getAllRegistedMember();
//echo json_encode(RegisteredMemberDAO::getAllRegistedMember());
$sql = "SELECT * FROM members";
$mysqli = db_connect();
$result = $mysqli->query($sql);
$members = array();
while ($row = $result->fetch_assoc()) {
$member = new RegisteredMemberDAO();
$member->setEmail($row['email']);
$member->setSn($row['sn']);
$member->setUsername($row['username']);
$member->setPlan($row['plan']);
array_push($members, $member);
}
$mysqli->close();
//echo serialize($member);
echo json_encode($members);
}

Answer 1

Normally this error happens if the result contains mixed encoding characters.
To fix it, use JSON_UNESCAPED_UNICODE as second parameter to json_encode function.
echo json_encode($members, JSON_UNESCAPED_UNICODE);
To check error occurred during json_encode put this code after json_encode.
echo json_last_error_msg(); // Print out the error if any
die(); // halt the script