Every API request sent to the {booker} application must include an authentication key and must be sent using the correct method (POST, PUT, GET ..) with valid parameters. Otherwise, the server returns an error. Following example creates a new order by receiving the order data from an external website.:

// 1. step - prepare collected customer and order data
$postData = [
	// required authentication API key
	"xauth" => "Sd5f8_ERtT8-Po6E...",
	// required customer data
	"Customer" => [
		"email" => "john.doe@gmail.com",
		"phone" => "0905 123456",
		"firstname" => "John",
		"lastname" => "Doe",
		"street_num" => "Toryská 123/a",
		"zip" => "04011",
		"city" => "Košice",
	],
	// required order data
	"Order" => [
		"car_pickup_datetime" => "2025-12-24",
		"select_pickup_time" => "10:00",
		"car_return_datetime" => "2025-12-28",
		"select_return_time" => "16:00",
		"select_pickup_place" => "address",
		"car_pickup_city" => "Košice",
		"car_pickup_street_num" => "Moldavská 123",
		"car_pickup_zip" => "04011",
		"select_return_place" => "same_as_pick",
		"notes_by_customer" => "Prosím prezvoniť pred príchodom.",
	],
	// vehicle data .. if missing, a "Request for quote" will be created
	"Car" => [
		...
	],
];

// 2. step - we send data to the API interface of the CarBooker application (in PHP)
$options = [
	"http" => [
		"method" => "POST",
		"timeout" => 5, // if necessary, adjust the settings, e.g. timeout 5 seconds
		"content" => http_build_query($postData), // order data
		"header" => [
			"Content-type: application/x-www-form-urlencoded; charset=utf-8",
		],
	],
];

// URL of the site where our CarBooker runs, to which we are sending the order
$url = "https://my-rent-car.site/api/order/create";
$errorMsg = $successMsg = "";

try {
	// the order data
	$ctx = stream_context_create($options);
	$response = file_get_contents($url, false, $ctx);

	// processing response - we have either the new order number, or list of errors
	if (!empty($response["errors"])) {
		$errorMsg = implode(" ", $response["errors"]);
	} elseif (!empty($response["orderId"])){
		$successMsg = "OK - create dnew order ID={$response["orderId"]}.";
	} else {
		$errorMsg = "Unknown error.";
	}
} catch (\Exception $e) {
	$errorMsg = $e->getMessage();
}

if (!empty($errorMsg)) {
	exit("Error - order not created - cause: ".$errorMsg);
}