Build a document generator with Express using REST API

In the digital age, the need for dynamic and automated document generation has become increasingly prevalent. Whether you’re creating reports, invoices, or any other type of document, having a reliable system in place can streamline your workflow.

In this article, we’ll explore how to build a Document Generator using Node and Express, two powerful technologies for server-side JavaScript development.

Prerequisite

• Node JS
• Express JS
• REST API

Approach to Create Document Generator:

• We’ll focus on a straightforward method using the Express.js framework and the pdfkit library to generate PDF documents. This approach is suitable for basic document generation needs. However, for more complex requirements, you might explore additional libraries or services.

Steps to Create Express Application:

Step 1: Create a directory in which the express application will store

mkdir Nodejs
cd Nodejs

Step 2: Initialize the project with the following command

npm init -y

Step 3: Install the required dependencies.

npm install pdfkit

Project Structure:

Project Structure

The updated dependencies in package.json file will look like:

"dependencies": {
    "express": "^4.18.2",
    "pdfkit": "^0.14.0",
}

Example: Building a document generator with Node.js and Express.js involves creating an API that receives requests, processes them, and generates the desired documents. In this example, I’ll demonstrate a simple document generator that generates PDF files using a popular library called pdfkit. You can install it using npm

Javascript

// app.js
const express = require('express');
const PDFDocument = require('pdfkit');
const fs = require('fs');

const app = express();
const port = 3000;

app.use(express.json());

app.post('/generate-document', (req, res) => {
  // Get data from the request body
  const { title, content } = req.body;

  // Create a new PDF document
  const doc = new PDFDocument();

  // Set response headers
  res.setHeader('Content-Type', 'application/pdf');
  res.setHeader('Content-Disposition', `attachment; filename=${title}.pdf`);

  // Pipe the PDF to the response
  doc.pipe(res);

  // Add content to the PDF
  doc.fontSize(18).text(title, { align: 'center' });
  doc.fontSize(12).text(content);

  // Finalize the PDF and end the response
  doc.end();
});

app.listen(port, () => {
  console.log(`Server is running on http://localhost:${port}`);
});

Steps to run server:

node app.js

Open command Prompt/terminal on your computer and run following command to test your document generator:

curl -X POST -H "Content-Type: application/json" 
-d "{\"title\": \"My Document\", \"content\": \"Hello, this is the content of my document.\"}" 
http://localhost:3000/generate-document > output.pdf

Now, type dir in cmd to see the output.pdf.

Output:

output.pdf in home directory.