Storing files on disk vs memory in Express - Hands-On Comparison

Storing Files on Disk vs Memory in Express

📖 Scenario: You are building a simple Express server that accepts file uploads. You want to learn how to store uploaded files either directly on the server's disk or temporarily in memory.This is useful when you want to process files quickly without saving them permanently, or when you want to save files for later use.

🎯 Goal: Create an Express server with two routes: one that saves uploaded files to disk, and another that stores files in memory. You will configure the file upload middleware accordingly and handle the uploaded files.

📋 What You'll Learn

Create an Express app with the express package

Use multer middleware for file uploads

Configure multer to store files on disk in a folder named uploads

Configure multer to store files in memory as buffers

Create two POST routes: /upload/disk and /upload/memory

Handle the uploaded file in each route and respond with the file's original name

💡 Why This Matters

🌍 Real World

Uploading files is common in web apps for user avatars, documents, or images. Knowing how to store files on disk or in memory helps optimize performance and storage.

💼 Career

Backend developers often handle file uploads. Understanding multer and Express routes is essential for building APIs that accept and process files.

1

Set up Express app and import multer

Create an Express app by importing express and multer. Then initialize the app with const app = express().

Express

const express = require('express')
const multer = require('multer')

const app = express()
// Your code here

Need a hint?

Use require('express') and require('multer') to import the packages.

2

Configure multer to store files on disk

Create a multer storage configuration called storageDisk that saves files to the uploads folder on disk using multer.diskStorage(). Then create an upload middleware called uploadDisk using multer({ storage: storageDisk }).

Express

const express = require('express')
const multer = require('multer')

const app = express()

// Configure multer to store files on disk
// Your code here

Need a hint?

Use multer.diskStorage() with destination and filename functions.

3

Configure multer to store files in memory

Create a multer upload middleware called uploadMemory that stores files in memory by setting storage to multer.memoryStorage().

Express

const express = require('express')
const multer = require('multer')

const app = express()

const storageDisk = multer.diskStorage({
  destination: function (req, file, cb) {
    cb(null, 'uploads')
  },
  filename: function (req, file, cb) {
    cb(null, file.originalname)
  }
})

const uploadDisk = multer({ storage: storageDisk })

// Configure multer to store files in memory
// Your code here

Need a hint?

Use multer.memoryStorage() inside the multer() call.

4

Create routes to handle file uploads

Create two POST routes on the Express app: /upload/disk and /upload/memory. Use uploadDisk.single('file') middleware for the disk route and uploadMemory.single('file') middleware for the memory route. In each route handler, respond with JSON containing the uploaded file's original name using res.json({ filename: req.file.originalname }).

Express

const express = require('express')
const multer = require('multer')

const app = express()

const storageDisk = multer.diskStorage({
  destination: function (req, file, cb) {
    cb(null, 'uploads')
  },
  filename: function (req, file, cb) {
    cb(null, file.originalname)
  }
})

const uploadDisk = multer({ storage: storageDisk })

const uploadMemory = multer({ storage: multer.memoryStorage() })

// Create POST route /upload/disk using uploadDisk.single('file')
// Create POST route /upload/memory using uploadMemory.single('file')
// Respond with JSON containing the uploaded file's original name
// Your code here

Need a hint?

Use app.post with the correct route paths and multer middleware. Access the uploaded file with req.file.originalname.