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Create dynamic PDFs from templates

Written by

Bernardo Palos

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Creating dynamic PDFs from templates is a powerful way to automate document generation for invoices, reports, certificates, contracts, and more. By combining predefined templates with variable data, you can quickly produce customized PDFs tailored to individual needs. This process not only saves time but also improves consistency and accuracy in document creation.

Understanding Dynamic PDF Generation

Dynamic PDF generation involves filling out a base PDF template with specific data at runtime. The template contains placeholders or fields that get replaced or populated with user data, database content, or real-time information. This approach contrasts with static PDFs, which are fixed and unchangeable once created.

Benefits of Using Templates for PDF Generation

  • Consistency: Templates ensure uniform style, formatting, and branding across all documents.

  • Efficiency: Automate repetitive document creation, reducing manual effort.

  • Customization: Insert personalized data for each recipient or use case.

  • Integration: Seamlessly connect with databases, APIs, and other data sources for dynamic content.

  • Scalability: Generate thousands of documents with minimal performance overhead.

Common Use Cases

  • Invoices and billing statements

  • Certificates and diplomas

  • Legal contracts and agreements

  • Event tickets and boarding passes

  • Personalized marketing materials and proposals

Approaches to Creating Dynamic PDFs from Templates

There are several technical approaches to generate PDFs dynamically depending on your requirements and technology stack.

1. Using Fillable PDF Forms (AcroForms)

  • Create a PDF form with editable fields using tools like Adobe Acrobat or LibreOffice.

  • Programmatically fill fields with data using libraries.

  • Generate a flattened, final PDF after filling.

Popular Libraries:

  • Java: iText, Apache PDFBox

  • Python: PyPDF2, pdfrw, reportlab (for advanced)

  • JavaScript: pdf-lib, pdf-fill-form

  • PHP: TCPDF, FPDI

2. Template Engines with PDF Rendering

  • Design templates in HTML or XML formats.

  • Use template engines (e.g., Handlebars, Jinja2) to inject dynamic content.

  • Render the final HTML as PDF using rendering engines (e.g., wkhtmltopdf, Puppeteer).

This method is flexible and allows rich styling via CSS.

3. Direct PDF Creation from Code

  • Generate entire PDFs on-the-fly with code.

  • Define layout, text, images, and other elements programmatically.

  • Good for highly customized PDFs without a pre-existing template.

Step-by-Step Guide: Generate Dynamic PDFs Using HTML Templates and Puppeteer (Node.js Example)

  1. Design an HTML Template

Create an HTML template file with placeholders for dynamic content:

html
<!DOCTYPE html>
<html>
<head>
  <style>
    body { font-family: Arial, sans-serif; }
    h1 { color: #333; }
    .invoice { width: 600px; margin: auto; }
    .item { border-bottom: 1px solid #ccc; padding: 10px 0; }
  </style>
</head>
<body>
  <div class="invoice">
    <h1>Invoice #{{invoiceNumber}}</h1>
    <p>Date: {{date}}</p>
    <p>Customer: {{customerName}}</p>
    <hr />
    {{#each items}}
      <div class="item">
        <strong>{{description}}</strong> - ${{price}}
      </div>
    {{/each}}
    <hr />
    <p>Total: ${{total}}</p>
  </div>
</body>
</html>

  1. Use a Template Engine (Handlebars) to Insert Data

javascript
const fs = require('fs');
const Handlebars = require('handlebars');

const templateHtml = fs.readFileSync('invoice-template.html', 'utf8');
const template = Handlebars.compile(templateHtml);

const data = {
  invoiceNumber: '12345',
  date: '2025-05-18',
  customerName: 'John Doe',
  items: [
    { description: 'Product A', price: 30 },
    { description: 'Product B', price: 20 },
  ],
  total: 50,
};

const filledHtml = template(data);

  1. Convert HTML to PDF Using Puppeteer

javascript
const puppeteer = require('puppeteer');

(async () => {
  const browser = await puppeteer.launch();
  const page = await browser.newPage();

  await page.setContent(filledHtml, { waitUntil: 'networkidle0' });
  await page.pdf({ path: 'invoice.pdf', format: 'A4' });

  await browser.close();
})();

Using Fillable PDF Forms with Python (Example with PyPDF2)

  1. Create a PDF form with fields (e.g., “name”, “date”, “amount”) using Adobe Acrobat.

  2. Fill the form fields programmatically:

python
from PyPDF2 import PdfReader, PdfWriter

reader = PdfReader("template_form.pdf")
writer = PdfWriter()

for page in reader.pages:
    writer.add_page(page)

fields = reader.get_fields()
data = {
    "name": "John Doe",
    "date": "2025-05-18",
    "amount": "$100"
}

writer.update_page_form_field_values(writer.pages[0], data)

with open("filled_form.pdf", "wb") as output_pdf:
    writer.write(output_pdf)

Best Practices for Dynamic PDF Generation

  • Use standardized templates: Define reusable templates with clear placeholders.

  • Sanitize input: Prevent injection and formatting errors by validating input data.

  • Optimize performance: Cache templates or precompile templates for large batch processes.

  • Keep designs simple: Complex PDF layouts may increase generation time and error risk.

  • Consider file size: Embed images wisely to avoid large PDF files.

  • Test across platforms: PDFs should render consistently on different devices and viewers.

Creating dynamic PDFs from templates unlocks automation and personalization for document workflows. Whether using fillable PDF forms or HTML-based templates with rendering engines, choosing the right approach depends on your use case, technology stack, and desired output quality. With careful design and implementation, you can generate professional, data-driven PDFs that scale with your business needs.

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