fileFilter refused file still uploaded in the diskStorage

given a code similar to this:

    const multerDiskStorage = multer.diskStorage({
      destination: function(req, file, cb) {
        cb(null, "tmp/uploads/");
      },
      filename: function(req, file, cb) {
        cb(null, hashFile(file));
      }
    });
    const multerInstance = multer({
      storage: multerDiskStorage,
      fileFilter: (req, file, cb) => {
        let error;
        if (!UploadImagesController.didReceiveFile(file))
          error = new Error("no file");
        if (!UploadImagesController.validImageByteSize(req))
          error = new Error("file bigger then permitted");
        if (!UploadImagesController.validImageType(file))
          error = new Error("file type not permitted");
        if (error) {
          cb(error, false);
        }
        cb(null, true);
      },
      limits: {
        fieldSize: 20000000,
        fileSize: 20000000
      }
    });

The fileFilter works as expected except for the fact that when a fileFilter cb with error and false is invoked the file still gets uploaded in the tmp/uploads folder (with a name that is not the result of invoking the filename callback propriety defined in the storage)

[YuriScarbaci]

Based on @HarshithaKP insight

I solved the problem the following way:

1. invoked cb with only one parameter
2. inside fileFilter returned the invokation of the cb instead of simply invoking it
3. instead of passing an Error instance to cb, actually passed a string (passing the Error instance resulted in losing the message!!!)

this seems to have solved the problem.

Based on this I think that the readme needs to be changed to correctly state the required syntax and gotchas to make this work!

https://github.com/expressjs/multer#filefilter

[YuriScarbaci]

@HarshithaKP Ty a lot for it, I will try it our ASAP,

From what i was able to infer the problem is invoking the cb with two arguments instead of invoking it only with the first argument?