fields params for get

fields.php

<?php

$fields = $_GET['fields'];

$fexp = explode(',', $fields);
$fname = array();

foreach ($fexp as $key => $value) {
	$fname[$value] = $value;
}

if (!empty($fname['user_id'])) {
	$result['user_id'] = $row['user_id'];
}

$response = array(
	'response' => $result
);

echo json_encode($response);

?>