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About Yatin Batra

An experience full-stack engineer well versed with Core Java, Spring/Springboot, MVC, Security, AOP, Frontend (Angular & React), and cloud technologies (such as AWS, GCP, Jenkins, Docker, K8).

Express.js File Upload

Hello! In this tutorial, we will learn about Express.js File Upload. More specifically, we will handle the file upload in the node.js application. To perform the file upload we will use a simple express middleware (named express-fileupload) as an npm package.

1. Introduction

1.1 Setting up Node.js

To set up Node.js on windows you will need to download the installer from this link. Click on the installer (also include the NPM package manager) for your platform and run the installer to start with the Node.js setup wizard. Follow the wizard steps and click on Finish when it is done. If everything goes well you can navigate to the command prompt to verify if the installation was successful as shown in Fig. 1.

express js file upload - npm installation
Fig. 1: Verifying node and npm installation

2. Express.js File Upload

To set up the application, we will need to navigate to a path where our project will reside. For programming stuff, I am using Visual Studio Code as my preferred IDE. You’re free to choose the IDE of your choice.

2.1 Setting up dependencies

Navigate to the project directory and run npm init -y to create a package.json file. This file holds the metadata relevant to the project and is used for managing the project dependencies, script, version, etc. Add the following code to the file wherein we will specify the required dependencies.

package.json

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{
  "name": "fileupload",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "keywords": [],
  "author": "daniel atlas",
  "license": "MIT",
  "dependencies": {
    "express": "^4.17.1",
    "express-fileupload": "^1.2.1"
  },
  "devDependencies": {
    "nodemon": "^2.0.7"
  }
}

To download the dependencies navigate to the directory path containing the file and use the npm install command. If everything goes well the dependencies will be loaded inside the node_modules folder and you are good to go with the further steps.

2.2 Creating the index controller

Create a controller file that will expose the endpoints responsible for showing the file upload index page to the user and perform the upload operation. The pre-requisite for the controller is that you will need a uploads folder in the project directory to store the uploaded files.

index.js

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const express = require('express');
const fileUpload = require('express-fileupload');
 
const app = express();
app.use(fileUpload());
 
app.get('/', (req, res) => {
    res.sendFile(__dirname + '/index.html')
});
 
app.post('/', (req, res) => {
    if (req.files) {
        // console.log(req.files);
        let file = req.files.file;
        let filename = file.name;
 
        // checking file size.
        // max size - 1 mb
        if (file.size > 1048576) {
            res.status(413).send('Payload too large');
        }
 
        //Todo - Other validations like file type etc are skipped for brevity.
 
        // using the mv() method to save the uploaded file in the
        // 'uploads' folder.
        file.mv('./uploads/' + filename, function (error) {
            if (error) {
                // console.log(error);
                res.status(500).json({ message: 'Error while uploading file' });
            } else {
                res.json({
                    message: 'File uploaded successfully',
                    data: {
                        name: filename,
                        mimetype: file.mimetype,
                        size: file.size
                    }
                });
            }
        });
    } else {
        return res.status(400).send({ message: 'No file uploaded' });
    }
});
 
// start app
const PORT = process.env.port || 5001;
app.listen(PORT, () => {
    console.log(`Server started on port ${PORT}`);
});

2.3 Creating an index page

Create the index HTML page that will be shown to the user to perform the file upload functionality.

index.html

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<!DOCTYPE html>
 
<html>
 
<head>
    <title>Index</title>
</head>
 
<body>
    <h1>File upload example in node.js</h1>
    <form id="upload-form" method="POST" enctype="multipart/form-data">
        <input type="file" name="file" />
        <input type="submit" value="Upload" />
    </form>
</body>
 
</html>

3. Run the Application

To run the application navigate to the project directory and enter the following command as shown in Fig. 4. If everything goes well the application will be started successfully on port number 5001.

express js file upload - starting the app
Fig. 2: Starting the application

4. Project Demo

When the application is started, open the browser of your choice and hit the following url – http://localhost:5001. The file upload index HTML page will be shown to the user as in Fig. 3.

express js file upload - page
Fig. 3: File upload page

Select the file of your choice and on successful upload, the message will be sent to the user as shown in Fig. 4.

Fig. 4: File upload successful

That is all for this tutorial and I hope the article served you with whatever you were looking for. Happy Learning and do not forget to share!

5. Summary

In this tutorial, we learned:

  • Introduction to express-fileupload
  • Steps to setup Node.js
  • Sample programming stuff

You can download the source code of this tutorial from the Downloads section.

6. Download the Project

This was a programming tutorial to handle file upload in a node.js application.

Download
You can download the full source code of this example here: Express.js File Upload

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