Error while sending data from form to sqlite database using Prisma in Next.js

I want to add data to my sqlite database. I am using Prisma. But doing so I am getting an error.

Error: 
Invalid `prisma.doctor.create()` invocation:

{
  data: '{"id":"1","firstName":"ehshan","middleName":"ehhsns","lastName":"khan","gender":"Female","specialization":"Cardiologist","date":"2022-06-10","phoneNumber":"1234456112","address":"vfdgh dhyh ssvg"}'
        
}

Argument data: Got invalid value '{"id":"1","firstName":"ehshan","middleName":"ehhsns","lastName":"khan","gender":"Female","specialization":"Cardiologist","date":"2022-06-10","phoneNumber":"1234456112","address":"vfdgh dhyh ssvg"}' on prisma.createOneDoctor. 

Provided String, expected DoctorCreateInput or DoctorUncheckedCreateInput:
type DoctorCreateInput {
  id: String

  firstName: String

  middleName: String

  lastName: String

  gender: String

  specialization: String

  date: String

  phoneNumber: String

  address: String
}

My code for saving the data is shown below.

import { PrismaClient,Prisma } from "@prisma/client"

const prisma = new PrismaClient();

export default async function handler(req, res) {
   
    let user = Prisma.DoctorCreateInput 
    user= JSON.stringify(req.body);
    const saveData = await prisma.doctor.create({
        data: user
    })

    res.json(saveData );
    //console.log(data)
}