CODEWITHSUNDEEP
javascriptnode.jsmulter
Coder1000
Coder1000

Reputation: 4461

How to prevent files from being uploaded with Multer unless they are images?

As title says.

I looked everywhere, couldn't find an answer.

CODE:

var upload = multer({dest:"./public/images/uploads/", limits: {fileSize: 250000}}).single("image");

PROBLEM

This does not prevent me from uploading a pdf if I choose to do so.

Upvotes: 4

Views: 3004

Answers (1)

silverfighter
silverfighter

Reputation: 6882

The docs state you should use fileFilter to possibly skip files for upload.
fileFilter (https://github.com/expressjs/multer#filefilter)

Set this to a function to control which files should be uploaded and which should be skipped. The function should look like this:

function fileFilter (req, file, cb) {

  // The function should call `cb` with a boolean
  // to indicate if the file should be accepted

  // To reject this file pass `false`, like so:
  cb(null, false)

  // To accept the file pass `true`, like so:
  cb(null, true)

  // You can always pass an error if something goes wrong:
  cb(new Error('I don\'t have a clue!'))

}

From the docs I would assume that the passed in file has a property mimetype (https://github.com/expressjs/multer#api). This could be a good hint for the decision if you want to skip.

EDIT: this GH issues (https://github.com/expressjs/multer/issues/114#issuecomment-231591339) contains a good example for the usage. It's important to not only look at the file extension because this can easily be renamed but also take the mime-type into account.

const path = require('path');

multer({
  fileFilter: function (req, file, cb) {

    var filetypes = /jpeg|jpg/;
    var mimetype = filetypes.test(file.mimetype);
    var extname = filetypes.test(path.extname(file.originalname).toLowerCase());

    if (mimetype && extname) {
      return cb(null, true);
    }
    cb("Error: File upload only supports the following filetypes - " + filetypes);
  }
});

HTH

Upvotes: 6

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