📁 File Uploads with Multer in Node.js

📌 What is Multer?

Multer is a middleware used to handle multipart/form-data, which is primarily used for uploading files. It is written on top of the busboy library and integrates easily with Express.js.

🎯 Why Use Multer?

• To allow users to upload files like images, PDFs, resumes, etc.
• It parses incoming file data from forms and saves it to the server.
• Customizable for file type validation, storage location, and naming.

⚙️ How to Use Multer?

Follow these steps:

1. Install using npm install multer
2. Configure storage with multer.diskStorage()
3. Set up an Express route to handle file uploads

🕒 When to Use Multer?

When you need to accept and store files sent via an HTML form or an API request (like image uploads in a profile form or documents in a resume upload form).

🧪 Example Code

// server.js
const express = require('express');
const multer = require('multer');
const path = require('path');

const app = express();

// Storage configuration
const storage = multer.diskStorage({
  destination: (req, file, cb) => {
    cb(null, 'uploads/'); // Upload folder
  },
  filename: (req, file, cb) => {
    cb(null, Date.now() + path.extname(file.originalname)); // Rename with timestamp
  }
});

// Multer middleware
const upload = multer({ storage: storage });

// POST Route
app.post('/upload', upload.single('file'), (req, res) => {
  res.send('File uploaded successfully!');
});

app.listen(5000, () => {
  console.log('Server running on http://localhost:5000');
});

🌐 Frontend HTML Form

<form action="/upload" method="POST" enctype="multipart/form-data">
  <input type="file" name="file" />
  <button type="submit">Upload</button>
</form>

📚 References

• Multer on NPM
• Express Multer Docs
• Upload & Retrieve Image with Mongoose