multiple files upload with express/multer - it is possible call some function for each file?

Question

I have following for upload files into S3

const upload = extension => multer({
  storage: multerS3({
    s3,
    bucket,
    acl,
    metadata(req, file, cb) {
      cb(null, { fieldName: file.fieldname });
    },
    ...
  }),
});

router.post(
  '/upload',
  upload('jpg').array('files', 5),
  (req, res) => {
    console.log(req.files);
    ...

It is possible to make some kind of function for each single uploading file (to write some information about file into DB before multer begin uploading next file) or for this I need upload each file separately?

Thank you