file.size undefined in Multer

Question

I'm using multer to handle a multi-file upload, and the middleware "filename", like this:

  filename: async (req, file, cb) => {
    console.log(Object.keys(file));
    ({ rows } = await db.query(`
    INSERT INTO public.files(
      uuid,
      nom,
      type,
      size
    )
    VALUES
    ($1, $2, $3, $4)
    RETURNING *`, [
      req.uuid,
      file.originalname,
      file.mimetype,
      file.size,
      // +req.headers["content-length"],
    ]));
    cb(null, uuid);
  },

The problem is that file.size remains undefined. I control that the size exists before sending the files to the API. When I check which properties are available (see the console.log), I only have 'fieldname', 'originalname', 'encoding', 'mimetype'.

If I use +req.headers["content-length"] it takes into account the size of all the request (all the files), and not only the current file.

Why can't I have the file size? Is it impossible or should I edit some setting I haven't found in the documentation?

Answer 1

Thanks to @traynor, here is what I did:

I added a middleware after the upload:

router.post('/',
  upload.array('files'),
  handleFiles,
  ...

I simplified my upload:

const storage = multer.diskStorage({
  destination: async (req, file, cb) => {
    let folder = config.get('api.files');
    req.uuid = uuid.v4();    
    folder += `/${req.uuid.charAt(0)}/${req.uuid.charAt(1)}/`;
    await fsPromises.mkdir(folder, { recursive: true });
    cb(null, folder);
  },
  filename: async (req, file, cb) => {
    cb(null, req.uuid);
  },
});

const upload = multer({ storage });

And I handled the logic with the new middleware:

const handleFiles = async (req, res, next) => {
  // my logic here, with req.files having f.size for each file
  // and f.originalname anf f.filename

  next();
}