Handling File Uploads with MEAN Stack

July 05, 2025

Introduction

Modern web applications often need to allow users to upload files — images, documents, or other media. In the MEAN stack (MongoDB, Express.js, Angular, Node.js), handling file uploads involves coordinating the backend (Node/Express) to receive and store files and the frontend (Angular) to send files via HTTP requests. Let’s break down how to implement file uploads in a MEAN app.

Setting Up the Backend with Node and Express

The most popular library for handling multipart/form-data in Node.js is Multer. First, install it in your project:

npm install multer

Then, configure a route to handle file uploads:

const express = require('express');

const multer = require('multer');

const router = express.Router();

const storage = multer.diskStorage({

destination: (req, file, cb) => cb(null, 'uploads/'),

filename: (req, file, cb) => cb(null, Date.now() + '-' + file.originalname),

});

const upload = multer({ storage });

// API endpoint

router.post('/upload', upload.single('file'), (req, res) => {

if (!req.file) return res.status(400).send('No file uploaded.');

res.status(200).json({ message: 'File uploaded successfully!', filePath: req.file.path });

});

module.exports = router;

This code creates an Express route /upload that saves uploaded files to an uploads/ directory and returns a success response.

Uploading Files from Angular

In your Angular component, you’ll need a file input and an HTTP request to send the selected file to the backend:

onFileSelected(event: any) {

const file = event.target.files[0];

const formData = new FormData();

formData.append('file', file);

this.http.post('http://localhost:3000/upload', formData).subscribe({

next: (res) => console.log('Upload success', res),

error: (err) => console.error('Upload error', err),

});

}

Here, Angular’s HttpClient sends a POST request with the file data to your Express endpoint.

Conclusion

File uploads are a common requirement in modern applications. With Multer handling uploads in Express, and Angular sending files with FormData, the MEAN stack offers a powerful solution for file handling. Always remember to validate file types and sizes for security, and consider storing files in cloud storage (like AWS S3) for scalability in production.

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