function purchase_edit()
{
    $session = Session::getInstance();
    if (!$session->checkLogin()) {
        return false;
    }
    $purchase = new Purchase();
    $purchase->id = isset($_POST['purchase']) ? $_POST['purchase'] : "";
    $purchase->status = isset($_POST['status']) ? $_POST['status'] : "";
    $purchase->update();
    if (isset($_POST['payment']) && is_numeric($_POST['payment'])) {
        $purchasePayment = new PurchasePayment();
        $purchasePayment->purchaseid = isset($_POST['purchase']) ? $_POST['purchase'] : "";
        $purchasePayment->amount = isset($_POST['payment']) ? $_POST['payment'] : "";
        $purchasePayment->add();
    }
}