How to limit the file size when uploading with multer?

Question

I'm making a simple file upload system with multer:

var maxSize = 1 * 1000 * 1000;

var storage = multer.diskStorage({
  destination: function (req, file, callback) {
    callback(null, 'public/upload');
  },
  filename: function (req, file, callback) {
    callback(null, file.originalname);
  },
  onFileUploadStart: function(file, req, res){
    if(req.files.file.length > maxSize) {
      return false;
    }
  }

});

var upload = multer({ storage : storage}).single('bestand');

router.post('/upload',function(req,res){
    upload(req,res,function(err) {
        if(err) {
            return res.end("Error uploading file.");
        }
        console.log(req.file);
        res.redirect(req.baseUrl);
    });
});

This all works fine and the file gets uploaded. The only thing that is not working is the limit on the max size. I made it so that onfileupload start the size of the file gets checked and if its to big it will return false. But the file still just gets uploaded.

It seems that onFileUploadStart isn't doing anything at all. I tried to console.log something in it, but nothing.

What am I doing wrong? How can I limit the file size when uploading with multer?

Where have you seen that you need to return `false` if `req.files.file.length > maxSize` in the handler of the even `onFileUploadStart`? — nbro, Jan 09 '16 at 18:57
A tutorial I was following. But I assume u say this is not the right way to stop the upload? — Merijn de Klerk, Jan 09 '16 at 19:01
Can you `console.log` (before the if statement) the file in that same handler? What do you see? — nbro, Jan 09 '16 at 19:08
Apparently maybe you should be using `fileFilter` instead of handling the even `onFileUploadStart` (where apparently the file size is not known yet or is 0...) by the way...Check here on how maybe you should be limiting the file sizes: https://github.com/expressjs/multer/issues/186 If you solve your problem, I encourage you to answer to your own question ;) — nbro, Jan 09 '16 at 19:13
There's here also another example of limiting the file size (among other things): https://github.com/expressjs/multer/issues/120: you need basically to specify the file size to a `limits` object that you pass as the property of the object that you pass to `multer`, i.e. something like this `var upload = multer({ storage : storage, limits: {fileSize: maxSize } }).single('bestand');`... — nbro, Jan 09 '16 at 19:27

score 80 · Accepted Answer · answered Jan 09 '16 at 20:37

80

There is no onFileUploadStart with the new multer API. If you want to limit the file size, you should instead add limits: { fileSize: maxSize } to the object passed to multer():

var upload = multer({
  storage: storage,
  limits: { fileSize: maxSize }
}).single('bestand');

answered Jan 09 '16 at 20:37

mscdex

104,356
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Thanks that works indeed. is it possible to pass the error? like filesize is too big? – Merijn de Klerk Jan 09 '16 at 20:47
9

You should be able to add an Express error handler and check `err.code === 'LIMIT_FILE_SIZE'`. – mscdex Jan 09 '16 at 20:51
@mscdex can you please given an example for the same – Prashant Bhanarkar Sep 15 '16 at 07:51
7

@mscdex I used fileSize too. But I dont think it stops uploading when limit exceeds. Rather it uploads the whole file & then checks limit. Am I missing something? – Jayadratha Mondal Sep 10 '17 at 07:31
1

@JayadrathaMondal If you can prove it, then I'd say submit an issue to the multer issue tracker on github. – mscdex Sep 10 '17 at 14:31
6

@mscdex yes its a issue, try uploading a 1GB file you can undersand. I had a conversation with LinusU (Multer maintainer). And the issue is listed, https://github.com/expressjs/multer/issues/344. Trying the multer v2.0 alpha. He said it may be fixed in v2 – Jayadratha Mondal Sep 10 '17 at 16:34
1

Is maxSize in bytes? – Anson Savage Apr 10 '19 at 00:24
2

@JayadrathaMondal the issue is still open. Have there been any updates to this issue? The last reply was in march and so far I haven't read anything that they're actively trying to fix this. – linus_hologram Apr 11 '20 at 13:56
1

@AnsonSavage /** Maximum size of each form field value in bytes. (Default: 1048576) */ – Filip Kováč May 25 '21 at 09:07

score 14 · Answer 2 · edited May 11 '22 at 11:29

I think it is you are looking. Have a great day.

const fileFilterMiddleware = (req, file, cb) => {
    const fileSize = parseInt(req.headers["content-length"])

    if ((file.mimetype === "image/png" || file.mimetype === "image/jpg" || file.mimetype === "image/jpeg" || file.mimetype === "application/octet-stream") && fileSize <= 1282810) {
        cb(null, true)
    } else if (file.mimetype === "video/mp4" && fileSize <= 22282810) {
        cb(null, true)
    } else {
        cb(null, false)
    }
}

score 5 · Answer 3 · answered Oct 13 '21 at 19:11

For anyone who uses Multer with Ts.ED. When I tried to upload a too large file (no matter what extension it had), I ended up with the following error showing up:

Cannot read properties of undefined (reading 'replace')

I did use the following code to fix this:

@Configuration({
  ...
  multer: {
    limits: {
      fieldNameSize: 300,
      fileSize: 1048576, // 10 Mb
    },
    fileFilter: (req, file, callback) => {
      const acceptableExtensions = ['.png', '.jpg'];
      if (!(acceptableExtensions.includes(Path.extname(file.originalname)))) {
        return callback(new Error('...'));
      }

      // added this
      const fileSize = parseInt(req.headers['content-length']);
      if (fileSize > 1048576) {
        return callback(new Error('...'));
      }
      // --


      callback(null, true);
    }
  }
})

Now it works.

How to limit the file size when uploading with multer?

3 Answers3

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