public async Task <IActionResult> AppPay(WeChatPayAppPayViewModel viewModel)
        {
            var request = new WeChatPayUnifiedOrderRequest()
            {
                Body           = viewModel.Body,
                OutTradeNo     = viewModel.OutTradeNo,
                TotalFee       = viewModel.TotalFee,
                SpbillCreateIp = viewModel.SpbillCreateIp,
                NotifyUrl      = viewModel.NotifyUrl,
                TradeType      = viewModel.TradeType,
            };
            var response = await _client.ExecuteAsync(request);

            if (response.ReturnCode == "SUCCESS" && response.ResultCode == "SUCCESS")
            {
                var req = new WeChatPayAppCallPaymentRequest()
                {
                    PrepayId = response.PrepayId,
                };
                var parameter = await _client.ExecuteAsync(req);

                // 将参数(parameter)给 ios/android端 让他调起微信APP(https://pay.weixin.qq.com/wiki/doc/api/app/app.php?chapter=8_5)
                ViewData["parameter"] = JsonConvert.SerializeObject(parameter);
                ViewData["response"]  = response.Body;
                return(View());
            }
            ViewData["response"] = response.Body;
            return(View());
        }
        public async Task <IActionResult> AppPay(string body, string out_trade_no, int total_fee, string spbill_create_ip, string notify_url, string trade_type)
        {
            var request = new WeChatPayUnifiedOrderRequest
            {
                Body           = body,
                OutTradeNo     = out_trade_no,
                TotalFee       = total_fee,
                SpbillCreateIp = spbill_create_ip,
                NotifyUrl      = notify_url,
                TradeType      = trade_type
            };
            var response = await _client.ExecuteAsync(request);

            ResponseModel responseModel = new ResponseModel()
            {
                code = HTTPResponseCode.PartialContent,
                data = response.Body
            };

            Dictionary <string, string> result = new Dictionary <string, string>();

            result.Add("return_code", response.ReturnCode);
            result.Add("return_msg", response.ReturnMsg);

            if (response.ReturnCode == "SUCCESS" && response.ResultCode == "SUCCESS")
            {
                var req = new WeChatPayAppCallPaymentRequest
                {
                    PrepayId = response.PrepayId
                };
                var parameter = await _client.ExecuteAsync(req);

                // 将参数(parameter)给 ios/android端 让他调起微信APP(https://pay.weixin.qq.com/wiki/doc/api/app/app.php?chapter=8_5)
                result.Add("parameter", JsonConvert.SerializeObject(parameter));
                responseModel.code = HTTPResponseCode.Successful;
            }
            else
            {
                responseModel.code = HTTPResponseCode.BadRequest;
                result.Add("err_code", response.ErrCode);
                result.Add("err_code_des", response.ErrCodeDes);
            }
            responseModel.message = JsonConvert.SerializeObject(result);
            return(Json(responseModel));
        }