Send object and additional attributes to express server via Axios and save with Mongoose

I'm posting a user object and a simple string to the backend via axios post and then want to store this data in MongoDB using mongoose. If I send the whole thing without the browser string, i.e. only the user object and process it in the backend, everything works. The object has all attributes except for the browser attribute. I added this later. So how can I save the user object 1:1 and also save other attributes, such as the browser attribute here? All that is actually saved is just the browser string

Function for save new User with mongoose:

//CREATE NEW USER
export const newUser = async (req, res, next) => {
try {
 const user = new User({ ...req.body.userD, browser: req.body.browser });

 const savedUser = await user.save();

 const myPromise = new Promise((resolve, reject) => {
   resolve(savedUser);
 });

 myPromise.then(() => {
  res.status(200).json("User saved");
 });

 } catch (error) {
  next(err);
 }
};

axios post :

let config = {
    method: 'post',
    maxBodyLength: Infinity,
    url: 'http://localhost:3999/server/user/new',
    headers: { 
      'Content-Type': 'application/json'
    },
    userD: data,
    browser:browser
};

await axios.request(config)
  .then((result) => {
    res.end(result.data)
  })

User Model:

import mongoose from "mongoose";

const UserSchema = new mongoose.Schema(
{
asn: {
  type: String,
},
city: {
  type: String,
},
continent_code: {
  type: String,
},
country: {
  type: String,
},
country_area: {
  type: Number,
},
country_calling_code: {
  type: String,
},
country_capital: {
  type: String,
},
country_code: {
  type: String,
},
country_code_iso3: {
  type: String,
},
country_name: {
  type: String,
},
country_population: {
  type: Number,
},
country_tld: {
  type: String,
},
currency: {
  type: String,
},
currency_name: {
  type: String,
},

in_eu: {
  type: Boolean,
},
ip: {
  type: String,
},
languages: {
  type: String,
},

latitude: {
  type: Number,
},
longitude: {
  type: Number,
},
network: {
  type: String,
},

org: {
  type: String,
},
postal: {
  type: Number,
},
region: {
  type: String,
},

region_code: {
  type: String,
},
timezone: {
  type: String,
},
utc_offset: {
  type: String,
},
version: {
  type: String,
},
browser: {
  type: String,
},
},
{ timestamps: true }
);

export default mongoose.model("User", UserSchema);

UPDATE

This is the data which is send to the express server:

> {
"data":{
"ip":"2003:c4:f720.xxx",
"network":"2003:xxx",
"version":"IPv6",
"city":"xxxx",
"region":"xxxx",
"region_code":"BW",
"country":"DE",
"country_name":"Germany",
"country_code":"DE",
"country_code_iso3":"DEU",
"country_capital":"Berlin",
"country_tld":".de",
"continent_code":"EU",
"in_eu":true,
"postal":"xxxx",
"latitude":xxxx,
"longitude":x.xx,
"timezone":"Europe/Berlin",
"utc_offset":"+0200",
"country_calling_code":"+49",
"currency":"EUR",
"currency_name":"Euro",
"languages":"de",
"country_area":357021,
"country_population":82927922,
"asn":"AS3320",
"org":"Deutsche Telekom AG"
},
"browser":"Browser"
}

and this is what is saved in mongodb

From your edit part I see that you need to access the ‘data’ field and than spread…

const user = new User({…req.body.userD.data, browser:req.body.browser})