Multer checking for file parameter?

Question

Node.js

Hello, but can you tell me how to properly validate in multer, what if there is no file parameter, give an error?

const fileFilter = async (req, file, next) => {
 ...
  return next(null, true);
};

const storage = multer.diskStorage({
  destination: (req, file, cb) => cb(null, pathGalleryCategories),
  filename: (req, file, cb) => cb(null, req.categoryId.toString())
});

const upload = multer({
  fileFilter,
  storage
});

routes.post('', upload.single('file'), (req, res) => {
  res.json({ id: req.categoryId });
});

It turns out that if you do not set the file parameter , then middlware upload.single('file') -> fileFilter does not work at all .
How to properly check? Thank you.

Answer 1

Add another middleware or wrap multer in a middleware

routes.post('',
  upload.single('file'),
  (req, res, next) => {
    next(req.file ? null : new Error('No file!'));
  },
  (req, res) => {
    res.json({ id: req.categoryId });
  }
);

or

routes.post('',
  (req, res, next) => {
    upload.single('file')(req, res, (err) => {
      if (err) return next(err);
      if (!req.file) return next(new Error('No file!'));
      next();
    });
  },
  (req, res) => {
    res.json({ id: req.categoryId });
  }
);