NodeJS file upload

multipart.js

const formidable = require('formidable');

exports.getMetadata = (req, res, next) => {

    const form = formidable({
        uploadDir: `${__dirname}/../controllers/uploads`,
        keepExtensions: true,
    });

    const filesInfos = [];

    form.onPart = (part) => {
		// I can filter here based on the mimetype but I don't have the information about the file size
		// The formidable package doesn't include it
		
        if (!part.mimetype) return form._handlePart(part);

        filesInfos.push({ name: part.name, mimetype: part.mimetype })
    };

    form.parse(req, (err, fields, files) => {
		// when parse() is called, files & fields are being processed already
    });

    return next();
};

route.js

const express = require('express');

const technologyController = require('../controllers/technologyController');

const multipart = require('../utils/multipart');
const validation = require('../utils/validation');

const router = express.Router();

router.route('/')
    .post(
        multipart.getMetadata, // get metadata from files & fields on multipart header
        validation.technology, // validation with express-validator module
        technologyController.createTechnology, // validate fields + files (size, mimetype) && create a record in database if ok
    )
;

module.exports = router;

PROBLEM :
Packages (multer, formidable, busboy...) usually store the file directly on the disk or memory with a custom validation in options. My problem is that, when I send fields & files at the same time, I don't want to waste resources on processing the entire file on the disk, or memory or even in a external storage like AWS S3, I want to stop everything and return an error to the client.

I would like the following illustrated in the express route above :

1°) Get the file and fields metadata in a multipart request and attach them to the request object
- file : size + mimetype
- fields : values

2°) Some validation on the properties created from previous step (validation with express-validator)

3°) technologyController.createTechnology which does the following :
- If ok : Process the stream of the file & store it directly into AWS S3 (without it being store in memory or in the local disk)
- If error : Doesn't process the file & don't create a record in the database but return a list of error to client

I hope my requirements are clear enough, if not don't hesitate.

I can't figure out how to do it properly, it's been days.