How to prevent Multer File Upload when input validation fails - node.js

Question

I'm creating a (POST) route to handle file uploads and also store some other properties to MongoDB in addition to the file path. The problem is when input validation fails, the file is still uploaded in the static(uploads) folder.
I'm using the Multer middleware for file uploads.
Setup
const storage = multer.diskStorage({
destination: (req, file, cb) => {
cb(null, "./uploads/");
},
filename: (req, file, cb) => {
cb(null, Date.now() + "-" + file.originalname);
}
});
const fileFilter = (req, file, cb) => {
if (file.mimetype === "image/jpeg" || file.mimetype === "image/png") {
cb(null, true);
} else {
//rejects storing a file
cb(null, false);
}
};
const upload = multer({
storage: storage,
limits: {
fileSize: 1024 * 1024 * 5
},
fileFilter: fileFilter
});
Fields
const seamUpload = upload.fields([
{ name: "stylePicture", maxCount: 1 },
{ name: "materialPicture", maxCount: 1 }
]);
Route
router.post("/", [auth, seamUpload], async (req, res) => {
const { error } = validateSeam(req.body);
if (error) return res.status(400).send(error.details[0].message);
const seam = new Seam({
stylePicture: req.files["stylePicture"][0].path,
materialPicture: req.files["materialPicture"][0].path,
description: req.body.description,
deliveryDate: req.body.deliveryDate,
customer: req.body.customerId
});
await seam.save();
res.send(seam);
});
Client(PostMan) Screenshot

Answer 1

Me as you faced with this problem.
one solution that I found is when your authentication in all modes seems error, in that case if you have a file from client, you can easily remove it like this:
if(req.file) {
fs.unlink(
path.join(__dirname, "go to root folder that 'req.file.path' leads to the file", req.file.path),
(err) => console.log(err));
}
or then in case that you got multi files, you should do the same way for each of them. If there is, I glad to here that.
I wish there be another way by using multer package for handling that.
good luck

Answer 2

You can have the validation middleware BEFORE the multer middleware.
That way, when the validation fails, all the subsequent middlewares would not be executed -- and thus, the files will not be uploaded.
Separate out the validation like so:
const validateSeamUpload = (req, res, next) => {
const { error } = validateSeam(req.body);
if (error) return res.status(400).send(error.details[0].message);
return next();
};
And then, mount this validateSeamUpload BEFORE the seamUpload middleware like so:
router.post("/", [auth, validateSeamUpload, seamUpload], async (req, res) => {
/** No need for validation here as it was already done in validateSeamUpload */
const seam = new Seam({
stylePicture: req.files["stylePicture"][0].path,
materialPicture: req.files["materialPicture"][0].path,
description: req.body.description,
deliveryDate: req.body.deliveryDate,
customer: req.body.customerId
});
await seam.save();
res.send(seam);
});
By the way, you can pass them as arguments to post() as well. Like so:
router.post("/", /** => See, no need for an array */ auth, validateSeamUpload, seamUpload, async (req, res) => {
/** your controller code */
});