Adding logic/validation to multer in node.js (express)

Question

During file upload I want to validate the file size, make sure that the uploaded file is an actual image and last but not least validate that a title has been written for the image. But this code doesn't work. What should I do?

var multer = require('multer'),
    upload = multer({
            dest: 'uploads/',
            onFileUploadStart: function(file, req, res){
                if(file.size > 1000000) {
                    res.send("Maximum picture size is 1 MB");
                    return false;
                }
                if(req.body.postname === ''){
                    res.send("Enter a title name for your post");
                    return false;
                }
                if(file.mimetype !== 'image/png' && file.mimetype !== 'image/jpg' && file.mimetype !== 'image/jpeg'){
                    res.send("Supported image files are jpeg, jpg, and png");
                    return false;
                }
            }
        });

And this is the route that gets the request through the form.

router.post('/uploadpost', upload.single('image'), function(req, res){
fs.rename(req.file.path, req.file.destination + req.file.originalname, function(err){
if(err){
    throw err;
}
});

var postObj = {
    Title : req.body.postname,
    Img_path : req.file.destination + req.file.originalname
}


var query = connection.query('INSERT INTO posts SET ?', postObj, function(err, result){
    if(err){
        throw err;
    }
});

Sven · Answer 1 · 2015-10-17T20:17:58.757

The multer middleware has always had a pretty vague API documentation, but after some digging I found that it uses busboy behind the scenes and that it pipes the limits option object to Busboy.

So to summarize, there is no onFileUploadStart option, but there is a limits property in the options object that you can define. Now if I understand everything correctly, you could do with this:

var multer = require('multer');
    upload = multer({
      dest: 'upload/',
      limits: {
        fileSize: 1000000
      }
    });

If you need more configuration options for the limits object, there is documentation available on Busboy's GitHub Repo

Hope this helps!

Adding logic/validation to multer in node.js (express)

1 Answers1