how to remove unnecessary fields

get_transactions_remove_nonpublic_fields.php

<?php
$transactions = [
    ["id" => 1, "name" => "John Smith", "x" => "y"],
    ["id" => 2, "name" => "Joe Adam", "z" => "a"],
];
$fields = ["id", "name"];
$callback = function ($transaction) use ($fields) {
    $keys = array_keys($transaction);

    foreach ($keys as $key) {
        if (!in_array($key, $fields)) {
            unset($transaction[$key]);
        }
    }
    return $transaction;
};
$transactions = array_map($callback, $transactions);
var_dump($transactions);