Middleware before Multer?

Question

Node.js

Hello. Tell me please. How to do it right, is it possible somehow in middlware before multer to get the parameters to validate them (or create an entry in the database whose id will be the file name in multer)?

app.use(express.urlencoded({ extended: true }));

routes.post(
  '',
  async (req, res, next) => next(req.body.some_params ? null : new Error('MISSING_PARAMS')),
  multer({ dest: './uploads' }).single('file'),
  (req, res) => res.json({ status: true })
);

Thank you.

Answer 1

No way. In order for req.body to appear, you need to parse the request body. This is exactly what multer does.
As it says in the documentation for body-parser :
Just look in the same Chrome developer tools how the form sent in the multipart/form-data format looks like and you will probably understand why it is difficult to parse. And, generally speaking, the order of the fields can be such that the file will go first, and then the id you need.
In general, as I said, you just need to save the file to temporary storage, and then transfer it where necessary.