Next Js File Attachments in Contact Forms - next.js

Question

I'm trying to upload a file to my server to send in the contact form and then have the file delete itself once sent. I've made a start with my code by using multer and I've followed a few guides that were using express to handle the api but I want to use the Next js api provided. I just can not seem to get this file to upload.
I've commented out the nodemailer call so it doesn't send an email every time I test it but, here is my current code.
// Next.js API route support: https://nextjs.org/docs/api-routes/introduction
import nodemailer from "nodemailer";
import multer from "multer";
export default async function handler(req, res) {
let Storage = multer.diskStorage({
destination: (req, file, callback) => {
callback(null, "../../files");
},
filename: (req, file, callback) => {
console.log(file);
callback(
null,
file.fieldname + "_" + Date.now() + "_" + file.originalname
);
},
});
let upload = multer({
storage: Storage,
}).single("careerCV");
upload(req, res, function (err) {
if (err) {
console.log(err);
return res.end("something went wrong");
} else {
var {
careerName,
careerEmail,
careerMessage,
careerTelephone,
careerBadge,
careerCV,
} = req.body;
console.log(careerName);
console.log(careerEmail);
console.log(careerMessage);
console.log(careerTelephone);
console.log(careerBadge);
console.log(careerCV);
}
});
// const {
// careerName,
// careerEmail,
// careerMessage,
// careerTelephone,
// careerBadge,
// careerCV,
// } = req.body;
// const transporter = nodemailer.createTransport({
// host: "smtp.gmail.com",
// port: 465,
// secure: true,
// auth: {
// user: process.env.user,
// pass: process.env.pass,
// },
// });
// try {
// const emailRes = await transporter.sendMail({
// from: `${careerName} <${careerEmail}>`,
// replyTo: `${careerName} <${careerEmail}>`,
// to: "deanparkim1987#gmail.com",
// subject: `Career Form Submission from ${careerName}`,
// html: `<p>You have a new Career form submission</p><br>
// <p><strong>Name: </strong> ${careerName}</p><br>
// <p><strong>Email: </strong> ${careerEmail}</p><br>
// <p><strong>Phone Number: </strong> ${careerTelephone}</p><br>
// <p><strong>Badge Number: </strong> ${careerBadge}</p><br>
// <p><strong>Message: </strong> ${careerMessage}</p>`,
// attachments: careerCV,
// });
// console.log("Message sent: %s", emailRes.messageId);
// } catch (error) {
// console.error(error);
// }
console.log(req.body);
res.status(200).json(req.body);
}