How to enter nested form data in postman

I have my schema like i have userDetials and in userDetails i have this principal Application Detials and in i have salutation field and now i want to enter input using form data in postman how i can do that and this is my schema:

{"selectedOption": "Individual","userDetails": {"principalApplicationDetails": {"salutation": "65fbe8ec74717b561f239821","name": "John Doe","fatherHusbandName": "Doe Sr.","motherName": "Jane Doe","identificationType": "CNIC","identificationNumber": "12345-1231441-5","issuanceDate": "2003-01-01","expiryDate": "2022-01-01","placeOfBirth": {"country": "65f339c5061ae53feb89c09a","province": "65f5e08ca2ebc406402e3efa","city": "65fd14466e03c2bef8cd98d9"            },"dateOfBirth": "2003-09-19","Nationality": "65f339c5061ae53feb89c09a","Gender": "Male","Religion": "65fb28c9a52265ff48f5fd2a","zakatDeduction": "Yes","nationalTaxNumber": "1234567890123","taxStatus": "Filer","correspondenceAddress": "123 Main St","mobileNumber": "0316-4251521",            // "post": "john.d@example.com""email":"242443424342432"        },    }}

this is my key that i am entering in form data in postman: userDetails[principalApplicationDetails][salutation] and this is my value for respective key: 65fbe8ec74717b561f239821 but it is showing me this error: userDetails.principalApplicationDetails.salutation: Path principalApplicationDetails.salutation is required." and this is my controller code:

import userModel from "../models/userModel.js";import fs from 'fs'export const createUserController = async (req, res) => {  try {// console.log(req.fields)      // Extract fields from the form data      console.log(req.fields)      const { selectedOption, userDetails} = req.fields;      const { cnicFrontImage, cnicBackImage,salutation } = req.files;      // const { principalApplicationDetails } = userDetails;      // const { salutation } = principalApplicationDetails;      // Validate the input data according to your schema      // Handle validation errors      // Create a new user instance based on the validated data      const newUser = new userModel({        selectedOption,        userDetails: {          ...userDetails,          // principalApplicationDetails: {          //   ...principalApplicationDetails,          //   salutation: salutation // Assigning salutation directly          // },          cnicFrontImage: {            data: fs.readFileSync(cnicFrontImage.path),            contentType: cnicFrontImage.type          },          cnicBackImage: {            data: fs.readFileSync(cnicBackImage.path),            contentType: cnicBackImage.type          }        }      });      // Save the new user instance to the database      await newUser.save();      // Send success response      return res.status(201).json({        success: true,        message: 'New user created successfully',        user: newUser      });  } catch (error) {    console.error('Error creating user:', error);    // Handle errors and send appropriate response    return res.status(500).json({      success: false,      message: 'Error creating user',      error: error.message    });  }};