/// <summary>
        /// 公眾號支付
        /// </summary>
        /// <param name="viewModel"></param>
        [HttpPost]
        public async Task<IActionResult> PubPay(WeChatPayPubPayViewModel viewModel)
        {
            var request = new WeChatPayUnifiedOrderRequest
            {
                Body = viewModel.Body,
                OutTradeNo = viewModel.OutTradeNo,
                TotalFee = viewModel.TotalFee,
                SpBillCreateIp = viewModel.SpBillCreateIp,
                NotifyUrl = viewModel.NotifyUrl,
                TradeType = viewModel.TradeType,
                OpenId = viewModel.OpenId
            };

            var response = await _client.ExecuteAsync(request, _optionsAccessor.Value);
            if (response.ReturnCode == WeChatPayCode.Success && response.ResultCode == WeChatPayCode.Success)
            {
                var req = new WeChatPayJsApiSdkRequest
                {
                    Package = "prepay_id=" + response.PrepayId
                };

                var parameter = await _client.ExecuteAsync(req, _optionsAccessor.Value);

                // 將參數(parameter)給 公眾號前端 讓他在微信內H5調起支付(https://pay.weixin.qq.com/wiki/doc/api/jsapi.php?chapter=7_7&index=6)
                ViewData["parameter"] = JsonSerializer.Serialize(parameter);
                ViewData["response"] = response.Body;
                return View();
            }

            ViewData["response"] = response.Body;
            return View();
        }