在匹配 PaypalAPI 付款标准时遇到问题

Question

我在网上商店使用 PaypalApi。

为了通过 API 发送付款，您的小计金额 + 税金 + 运费必须等于订单的总金额，并且 Paypal 仅限于小数点后 2 位。我的问题是，有时某些值会变成 3 位小数，当我尝试将其格式化为两位小数时，我的计算最终会出错。不管我怎么扭扭捏捏，我最终都会得到一个不等于 TotalAmount 的方法。

这是 paymentMethod 的代码。

  private Payment ExecutePayment(APIContext apiContext, string payerId, string paymentId)
    {
        var paymentExecution = new PaymentExecution() { payer_id = payerId };
        this.payment = new Payment() { id = paymentId };
        return this.payment.Execute(apiContext, paymentExecution);
    }

    private Payment CreatePayment(APIContext apiContext, string redirectUrl)
    {

        //similar to credit card create itemlist and add item objects to it

        var countryParams = LanguageService.GetUiCultureByCountryPrefix(Country);
        var productsInPaypalCart = (List<Dictionary<string, object>>)Session["ProductsInPaypalCart"];
        double subtotalAmount = 0;
        double unitPrice = 0;
        double taxedUnitPrice = 0;
        var itemList = new ItemList() { items = new List<PayPal.Api.Item>() };
        double shipping = 0;
        double totalAmount = 0;
        double taxedAmount = 0;
        double taxInTwoDecimails = 0;
        double subtotalAmountInTwoDecimals = 0;
        foreach (var product in productsInPaypalCart)
        {

            var dbProduct = Service.ProductService.GetProduct(int.Parse(product["reference"].ToString()), Country);

            shipping = dbProduct != null && dbProduct.ShippingFee.HasValue && shipping < dbProduct.ShippingFee ? dbProduct.ShippingFee.Value : shipping;

            unitPrice = (int)product["unit_price"] / 100;
            taxedUnitPrice = (unitPrice  * 0.875);

            itemList.items.Add(new PayPal.Api.Item()
            {

                name = (string)product["name"],
                currency = countryParams.Currency,
                price = (taxedUnitPrice).ToString("F").Replace(",", "."),
                quantity = Convert.ToString(product["quantity"]),

            }


            );

            subtotalAmount += (taxedUnitPrice * (int)product["quantity"]);
            totalAmount += (unitPrice * (int)product["quantity"]);
            taxedAmount += ((totalAmount * 0.125) + shipping * 0.25);

        }
        var b = Math.Round((decimal)subtotalAmount, 2);
        subtotalAmountInTwoDecimals += Convert.ToDouble(b);
        var a = Math.Round((decimal)taxedAmount, 2);
        taxInTwoDecimails += Convert.ToDouble(a);


        var payer = new Payer() { payment_method = "paypal" };

        // Configure Redirect Urls here with RedirectUrls object
        var redirUrls = new RedirectUrls()
        {
            cancel_url = redirectUrl,
            return_url = redirectUrl
        };

        // similar as we did for credit card, do here and create details object
        var details = new Details()
        {
            tax = ((totalAmount * 0.125) + shipping * 0.25).ToString("F").Replace(",", "."),
            shipping = (shipping * 0.75).ToString("F").Replace(",", "."),
            subtotal = (subtotalAmount).ToString("F").Replace(",", ".")
        };

        // similar as we did for credit card, do here and create amount object
        var amount = new Amount()
        {
            currency = countryParams.Currency,
            total = ((subtotalAmount + taxInTwoDecimails)  + (shipping * 0.75)).ToString("F").Replace(",", "."), // Total must be equal to sum of shipping, tax and subtotal.
            details = details
        };

        var transactionList = new List<Transaction>();

        transactionList.Add(new Transaction()
        {
            description = "Transaction description.",
            invoice_number = Guid.NewGuid().ToString(),
            amount = amount,
            item_list = itemList
        });

        this.payment = new Payment()
        {
            intent = "order",
            payer = payer,
            transactions = transactionList,
            redirect_urls = redirUrls
        };

        // Create a payment using a APIContext

        return this.payment.Create(apiContext);

    }

提前致谢。

Answer 1

听起来您正在分别计算“总金额”和“小计 + 税 + 运费”的总和。为什么不首先确保小计、税收和运费只计算到小数点后 2 位，然后将它们加在一起并发送 那个 作为总金额？ IE 以 2 位小数完成所有操作