How to define multer storage in different file? - node.js

Question

I have a node application with express.
The server is at server.js and I have routers set up like the following:
app.use('/xyz', xyz);
app.use('/abc', abc);
The routers xyz and abc are in different route modules in /routes.
I want to use multer to upload images to MongoDB. The endpoint for uploading files is /xyz/upload
storage = new GridFsStorage({
url: process.env.DB_URL,
file: (req, file) => {
return new Promise((resolve, reject) => {
const filename = file.originalname;
const fileInfo = {
filename: filename,
bucketName: 'uploads'
};
resolve(fileInfo);
});
}
});
How can I define this const upload = multer({ storage }); in the xyz router file?
All the examples on the internet show multer being defined in server.js and app.post(). What to do if I have a router defined in a different module?

Answer 1

If you are looking for a cleaner architecture then I would suggest following the separation of concerns principle (SoC) and treat the file handling middleware in a separate file as follows:
const multer = require("multer");
const storage = multer.diskStorage({
destination: function (req, file, cb) {
cb(null, "./public/uploads");
},
filename: function (req, file, cb) {
const uniqueSuffix = Date.now() + "-" + Math.round(Math.random() * 1e9);
cb(
null,
new Date().getTime() + "-" + uniqueSuffix + "-" + file.originalname
);
},
});
const fileFilter = (req, file, cb) => {
// reject all files except jpeg
if (file.mimetype === "image/jpeg") {
cb(null, true);
} else {
cb(null, false);
}
};
module.exports = multer({
storage: storage,
limits: {
fileSize: 1024 * 1024 * 15, // 15mb max size,
},
fileFilter: fileFilter,
});
then, in your routes, a simple require if you are working with CommonJS should be enough:
const upload = require("./fileHandling");
server.post(
`/route`,
upload.array('Photos', 6),
controller,
);
It did the trick for me, hope it helps!