我在Express中的req.body有什么问题，它不会让我解析JSON？

我正在从我的前端向我正在从Nodejs提供的Express路由处理程序发出一个ajax POST请求。

我的数据是按照以下方式从结尾发送的，如输出到控制台所确认的：

This data is sent from front.end: {"panReferenceID":"0987","walletAccountEmailAddressHash":"8907","clientWalletAccountId":"879","visaTokenScore":"0987","visaTokenDecisioning":"879","addressVerificationResultCode":"rty67u89i9o0","cvv2ResultsCode":"897","locale":"34567890","deviceInfo":{"deviceId":"hgjk","deviceLanguageCode":"890","osVersion":"ertyuio","osBuildID":"879","deviceIDType":"87","deviceManufacturer":"9876","deviceBrand":"897","deviceModel":"34567890","deviceName":"980","deviceNumber":"980","deviceLocation":"9876","deviceIpAddressV4":"789"},"encryptedData":"87"},http://localhost:3000/vtis/tokenRequestors/5/tokens/987/tokenChanged?eventType=TOKEN_CREATED&eventID=254

在后端，我得到了适当的请求对象。当我尝试使用以下语句将其记录到控制台时：

console.log("This is the request from the clientSide..." + JSON.stringify(req.body));

我在终端上得到这个：

This is the request from the clientSide...{"{\"panReferenceID\":\"0987\",\"walle
tAccountEmailAddressHash\":\"8907\",\"clientWalletAccountId\":\"879\",\"visaToke
nScore\":\"0987\",\"visaTokenDecisioning\":\"879\",\"addressVerificationResultCo
de\":\"rty67u89i9o0\",\"cvv2ResultsCode\":\"897\",\"locale\":\"34567890\",\"devi
ceInfo\":{\"deviceId\":\"hgjk\",\"deviceLanguageCode\":\"890\",\"osVersion\":\"e
rtyuio\",\"osBuildID\":\"879\",\"deviceIDType\":\"87\",\"deviceManufacturer\":\"
9876\",\"deviceBrand\":\"897\",\"deviceModel\":\"34567890\",\"deviceName\":\"980
\",\"deviceNumber\":\"980\",\"deviceLocation\":\"9876\",\"deviceIpAddressV4\":\"
789\"},\"encryptedData\":\"87\"}":""}

为什么请求在引号之前添加\be？

我怀疑这是我问题的根源。我无法解析请求对象。我尝试过使用：

req.body["panReferenceID"] 

例如，要获取请求对象中的第一个数据项，我在终端中得到“未定义”...

ajax post请求发生了什么，为什么我无法解析它？

有人看到我在这里看不到的错误???

谢谢..

编辑

这是我的客户端代码。当我将它输出到控制台然后再支持到后端它很好，在后端它变为看起来像它有空值：

var deviceInfo = {
                'deviceId':deviceID, 'deviceLanguageCode': deviceLanguageCode, 
                'osType':osType, 'osVersion':osVersion, 'osBuildID':osBuildID,
                'deviceType': deviceType, 'deviceIDType':deviceIDType, 
                'deviceManufacturer':deviceManufacturer, 'deviceBrand':deviceBrand,
                'deviceModel':deviceModel, 'deviceName':deviceName, 'deviceNumber':deviceNumber,
                'deviceLocation':deviceLocation, 'deviceIpAddressV4':deviceIpAddressV4,
                'locationSource':locationSource,'tokenProtectionMethod':tokenProtectionMethod
            };

            // Need a JWE encryption mechanism for JWE data

            var requestPayload = {
                'panReferenceID':panReferenceID,
                'walletAccountEmailAddressHash':walletAccountEmailAddressHash,
                'clientWalletAccountId':clientWalletAccountId,
                'visaTokenScore':visaTokenScore,
                'visaTokenDecisioning':visaTokenDecisioning,
                'panSource':panSource,
                'addressVerificationResultCode':addressVerificationResultCode,
                'cvv2ResultsCode':cvv2ResultsCode,
                'consumerEntryMode':consumerEntryMode,
                'locale':locale,
                'deviceInfo':deviceInfo,
                'encryptedData':encryptedData
            }

            // reset form on submit
            // document.form["#tcnform"].reset()

            // async call to post form data to server to wait for response
            $.ajax({

                url: 'http://localhost:' + clientPort.toString() + '/vtis/tokenRequestors/' + inputTokenRequestorID + '/tokens/' + inputTokenReferenceID + '/tokenChanged?eventType=' + eventType + '&eventID=' + eventID,
                data: requestPayload,
                dataType: 'json',
                type: 'POST',
                Content-Type: 'application/json',

                success: function(data, textStatus){
                    console.log("DEBUG: Response from server: " + data);
                    console.log("Sent Token Create Notification: " + data);
                    console.log("This data is sent from front.end: " + this.data + "," + this.url);

                    // Need to get data from server based on tests and load to text field for copy by user






                },
                error: function(request, status, error){
                    var val = request.responseText;
                    console.log("Error in Ajax: " + val);
                }
            });

        }

var bodyParser = require('body-parser')

// parse application/x-www-form-urlencoded
app.use(bodyParser.urlencoded({ extended: false }))

// parse application/json
app.use(bodyParser.json())