Node.js File Upload to a Local Server Or to the Cloud

Probably one of the best things to happen to JavaScript developers, Node.js empowers them to write and ship JavaScript on the back end. Thanks to Node.js, front-end developers can become full-stack developers in a snap.

The procedures below describe how to Node.js file upload's to your local server or to the cloud at Cloudinary.

Set Up a Node Project

First, download and install Node.js on your system. Afterwards, set up a Node.js back-end server with a package, such as Express. Do the following:

1. Create an upload directory and run npm init there to generate a package.json file:

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   npm init

2. In the same directory, install Express:

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   npm install express --save

3. Create an index.js file with the code below:

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   const express = require('express')
   const app = express()
   const port = 3000
   
   app.get('/', (req, res) => res.json({ message: 'Hello World!' }))
   
   app.listen(port, () => console.log(`This is the beginning of the Node File Upload App`))

4. Run the project with the command node index.js.

   Your back-end server is now up and running.

   

   Afterwards, multer creates an images directory in which to display the details of the recently uploaded file in your console. See this example:

   

   For simultaneous multiple file uploads, just change fileUpload.single to fileUpload.array:

...
app.post('/photos/upload', fileUpload.array('image', 5), function (req, res, next) {
      console.log("Images ", req.file);  
})

5 above can be any numeric value, denoting the number of files you plan to upload.

Step 2: Set up file uploads to Cloudinary

Completing step 1 enables you to upload files to your local server. For multiple files, best store them in a central location like Cloudinary and behind a content delivery network (CDN) at scale for efficient retrieval and delivery to users.

This step establishes the mechanics for uploading files to Cloudinary.

As a prerequisite, sign up for a free account on Cloudinary. Note your cloud name and API keys on the dashboard.

Now do the following.

1. Rewrite multer to accept zero arguments:

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   const fileUpload = multer()

   Instead of being written to a local directory, the uploaded files now reside in memory temporarily as a buffer.

2. Install Cloudinary’s Node.js SDK and the streamifier library:

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   npm install cloudinary 
   npm install streamifier

3. Make the cloudinary and streamifier required libraries in your codebase:

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   ...
   const cloudinary = require('cloudinary').v2
   const streamifier = require('streamifier')
   ...

4. Rewrite the /upload endpoint code to upload files to Cloudinary:

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   app.post('/upload', fileUpload.single('image'), function (req, res, next) {
   let streamUpload = (req) => {
       return new Promise((resolve, reject) => {
           let stream = cloudinary.uploader.upload_stream(
             (error, result) => {
               if (result) {
                 resolve(result);
               } else {
                 reject(error);
               }
             }
           );
   
          streamifier.createReadStream(req.file.buffer).pipe(stream);
       });
   };
   
   async function upload(req) {
       let result = await streamUpload(req);
       console.log(result);
   }
   
   upload(req);
   });

Recall that you rewrote multer earlier to process and store uploaded files temporarily as a buffer. streamifier now converts the uploaded buffer to a readable stream, after which Cloudinary’s upload_stream method streams directly to the cloud.

The returned result looks like this, complete with the details on the recently uploaded file:

Now you can fetch the URL from the JSON response and store it in the database. Mission accomplished.

A Word About Cloudinary’s Node.js SDK

Besides uploading images and videos, Cloudinary’s Node.js SDK can also transform, optimizatize, and deliver them. You can seamlessly integrate those capabilities with your Node.js app. For details, see the related documentation.

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