Uploading Files to the Web: Receiving multipart/form-data in Node JS

Whether you’re building a social media platform, a photo sharing app, or an e-commerce website, allowing users to upload files to the web is essential. In this article, we’ll explore how to receive multipart/form-data in Node JS, a popular backend language for web development.

What is multipart/form-data?

When a user uploads a file to a web server, the data is sent as a “multipart/form-data” request. This type of request is commonly used for file uploads and allows the client to send multiple sets of data in a single request. In Node JS, we can use the “multer” middleware to handle multipart/form-data requests and process the uploaded files.

Using multer to receive multipart/form-data

First, we need to install the “multer” package using npm:

npm install multer

Once installed, we can require the “multer” package in our Node JS application and set up a storage configuration to define where the uploaded files will be stored on the server:


var multer = require('multer');
var storage = multer.diskStorage({
destination: function (req, file, cb) {
cb(null, 'uploads/') // specify the folder where uploaded files will be stored
},
filename: function (req, file, cb) {
cb(null, file.fieldname + '-' + Date.now())
}
})
var upload = multer({ storage: storage })


Next, we can use the “upload” middleware to process the incoming multipart/form-data requests and save the uploaded files to the specified destination:


app.post('/upload', upload.single('file'), function (req, res, next) {
// file has been uploaded and saved to the server
res.send('File uploaded successfully');
})


Conclusion

Receiving multipart/form-data in Node JS is a crucial step in building web applications that allow users to upload files. With the “multer” middleware, we can easily process and save the uploaded files to the server, giving us the flexibility to build a wide range of file upload features for our web applications.

For more articles and tutorials on web development, be sure to check out the Learn Web Dev with Austin Gil website.