How to handle erros from multer custom storage? - node.js

Question

I'm using multer with sharp and a custom storage, image upload is set and it works fine but I can not handle the errors correctly.
It is crashing my server when I upload for example a wrong file type or when a file is too big.
on my app.js
const upload = multer({
storage: new customStorage({
destination: function(req, file, cb) {
cb(
null,
path.join(
__dirname,
'/images',
new Date().toISOString().replace(/:/g, '-') +
'-' +
file.originalname.replace(/\s+/g, '-')
)
);
}
}),
limits: { fileSize: 5000000 }
});
on my customStorage.js
const fs = require('fs');
const sharp = require('sharp');
const nodePath = require('path');
function getDestination(req, file, cb) {
cb(null, 'images');
}
function customStorage(opts) {
this.getDestination = opts.destination || getDestination;
}
customStorage.prototype._handleFile = function _handleFile(req, file, cb) {
this.getDestination(req, file, function(err, path) {
if (err) return cb(err);//***the problem is here.***
const outStream = fs.createWriteStream(path);
const transform = sharp().resize(200, 200);
file.stream.pipe(transform).pipe(outStream);
outStream.on('error', cb);
outStream.on('finish', function() {
cb(null, {
path: 'images/' + nodePath.basename(path),
size: outStream.bytesWritten
});
});
});
};
customStorage.prototype._removeFile = function _removeFile(req, file, cb) {
fs.unlink(file.path, cb);
};
module.exports = function(opts) {
return new customStorage(opts);
};
When i upload another file it says:
Error: Input buffer contains unsupported image format
Emitted 'error' event at:
at sharp.pipeline (/Users/David/nodejs-app/node_modules/sharp/lib/output.js:687:18)
I would like to handle the errors with express like this instead.
return res.status(422).render('admin/edit-product', {flash message here.}
That's the way I do it with other errors like when the field is empty.

Answer 1

You can throw the error in your Multer custom storage (which is already being done with cb(err) ), and then catch it in a middleware for express.
const upload = multer({
storage: new customStorage({
destination: function(req, file, cb) {
cb(
null,
path.join(
__dirname,
'/images',
new Date().toISOString().replace(/:/g, '-') +
'-' +
file.originalname.replace(/\s+/g, '-')
)
);
}
}),
limits: { fileSize: 5000000 }
});
var uploadMiddleware = function(req, res, next){
var handler = upload.single('media'); //use whatever makes sense here
handler(req, res, function(err){
//send error response if Multer threw an error
if(err){
res.status(500).render('admin/edit-product', "flash message here.");
}
//move to the next middleware, or to the route after no error was found
next();
});
}
Then use the uploadMiddleware in your express route:
app.post('/route/edit', uploadMiddleware, function (req, res) {
//handle request and render normally
});