Generate PDF with ChartJS and PDFKit

pdf-charts-generator.js

const fs = require('fs')
const tmp = require("tmp");
const PDFDocument = require('pdfkit');
const MemoryStream = require('memorystream');
const { ChartJSNodeCanvas } = require('chartjs-node-canvas');

export async function generatePDFWithCharts() {
  // Sample chart with ChartJS
  const chartJSNodeCanvas = new ChartJSNodeCanvas({ type: 'png', width: 800, height: 600 });
  const configuration = {
    type: 'bar',
    data: {
      labels: ['Q1', 'Q2', 'Q3', 'Q4'],
      datasets: [{
        label: 'Users',
        data: [50, 60, 70, 180]
      }]
    }
  };

  // Generate chart image
  const imageBuffer = await chartJSNodeCanvas.renderToBuffer(configuration);

  // Write the chart image to the system because the PDF needs a path
  const tempImg = tmp.fileSync({ postfix: ".png" });
  fs.writeFileSync(tempImg.name, imageBuffer);

  // Prepare the PDF
  const doc = new PDFDocument;
  doc.fontSize(25).text('Here is some vector foo...', 100, 80);

  // Use the image we just wrote to the system
  doc.image(tempImg.name, 0, 15, {width: 300})
    .text('Proportional to width', 0, 0);

  // Create a stream to hold the PDF in memory
  const memStream = new MemoryStream(null, {
    readable : false
  });

  doc.pipe(memStream);

  // Write the PDF stream buffer to the file system
  doc.on('end', function () {
    const pdfBuffer = Buffer.concat(memStream.queue)

    // From here you'll be able to read the file and handle it as you wish
    const tempPDF = tmp.fileSync({ postfix: ".pdf" });

    fs.writeFileSync(tempPDF.name, pdfBuffer);
    console.log({ tempPDF })
  })

  doc.end();
}