$databaseDirectory = $_SERVER['DOCUMENT_ROOT'] . "/data/test";

$storeConfiguration = [
    "auto_cache" => true,
    'timeout' => false,
];
$userStore = new \SleekDB\Store("customers", $databaseDirectory, $storeConfiguration);

$newUsers = [
    [
        "username" => "Lisa",
        "age" => 17,
        "address" => [
            "street" => "up street",
            "streetNumber" => 48,
            "postalCode" => "1822",
        ],
    ],
    [
        "username" => "Bob",
        "age" => 20,
        "address" => [
            "street" => "down street",
            "streetNumber" => 12,
            "postalCode" => "8174",
        ],
    ],
];

$oldUsers = $userStore->findAll();

$updateOrInsertData = [];

foreach ($newUsers as $user) {
    // Check if there is already a user with that username
    if ($oUser = $userStore->findOneBy(['username', '=', $user['username']])) {
        // Already inside database, add _id to the new element
        $updateOrInsertData[] = array_merge($user, ['_id' => $oUser['_id']]);
    } else {
        // Not inside database, just add it
        $updateOrInsertData[] = $user;
    }
}

// Update all existing documents with the new data
$userStore->updateOrInsert($newUsers);