Dart Requires Chilkat v11.7.0+

Fill a PDF Template: Replace {{placeholders}} with Values

See more PDF Text Replacement Examples

Demonstrates the TextReplace method on an invoice template whose values are written as placeholders such as {{customer}} and {{total}}. The "placeholders" object names each placeholder and the text to put in; every occurrence on the page is replaced, including a placeholder inside a sentence or inside a label such as "Tax ({{taxRate}}):". The text is redrawn with the font the template used, so the result looks like the template, and a value that is right-aligned in the template stays right-aligned. The changes are written by WriteFile. Dart

import 'package:chilkat/chilkat.dart';

void main() {
  var success = false;

  // This example requires the Chilkat API to have been previously unlocked.
  // See Global Unlock Sample for sample code.

  // The PDF used in this example is available at invoice_template.pdf

  final pdf = CkPdf();
  success = true;
  try {
    pdf.loadFile('qa_data/pdf/invoice_template.pdf');
  } on ChilkatException {
    success = false;
  }
  if (!success) {
    print(pdf.lastErrorText);
    return;
  }

  // The template has these placeholders in its page text:
  //   {{customer}} (twice: "Bill To:" and the closing sentence), {{date}}, {{po}},
  //   two item rows: {{qty1}} {{desc1}} {{price1}} {{amount1}} and {{qty2}} {{desc2}} {{price2}} {{amount2}},
  //   {{subtotal}}, "Tax ({{taxRate}}):" with {{tax}}, and {{total}}.
  final json = CkJsonObject();
  json.updateString('placeholders.customer', 'Acme Corp');
  json.updateString('placeholders.date', '2026-10-18');
  json.updateString('placeholders.po', 'PO-88213');
  json.updateString('placeholders.qty1', '2');
  json.updateString('placeholders.desc1', 'Cordless drill, 18 V');
  json.updateString('placeholders.price1', '\$460.00');
  json.updateString('placeholders.amount1', '\$920.00');
  json.updateString('placeholders.qty2', '6');
  json.updateString('placeholders.desc2', 'Galvanized hinge, 4 inch');
  json.updateString('placeholders.price2', '\$12.50');
  json.updateString('placeholders.amount2', '\$75.00');
  json.updateString('placeholders.subtotal', '\$995.00');
  json.updateString('placeholders.taxRate', '7.35%');
  json.updateString('placeholders.tax', '\$73.13');
  json.updateString('placeholders.total', '\$1,068.13');

  // "apply" makes every replacement, or none: if any value cannot be drawn with the
  // template's font, the method returns false, the PDF is unchanged, and jsonOut says why.
  final jsonOut = CkJsonObject();
  success = true;
  try {
    pdf.textReplace('apply', json, jsonOut);
  } on ChilkatException {
    success = false;
  }
  if (!success) {
    print('Not applied: ${jsonOut.emit()}');
    if (!success) {
      print(pdf.lastErrorText);
      return;
    }
  }

  // One entry per placeholder: the pages it was found on and how many times it was replaced.
  var i = 0;
  final countI = jsonOut.sizeOfArray('replacements');
  while (i < countI) {
    jsonOut.i = i;
    print('${jsonOut.stringOf('replacements[i].field')}: ${jsonOut.intOf('replacements[i].count')} on page(s) ${jsonOut.stringOf('replacements[i].pages')}');
    i++;
  }

  // The replacements stay in memory until the PDF is written.
  success = true;
  try {
    pdf.writeFile('qa_output/invoice_filled.pdf');
  } on ChilkatException {
    success = false;
  }
  if (!success) {
    print(pdf.lastErrorText);
    return;
  }

  print('Wrote qa_output/invoice_filled.pdf');

  // Sample output:

  // customer: 2 on page(s) 1
  // date: 1 on page(s) 1
  // po: 1 on page(s) 1
  // qty1: 1 on page(s) 1
  // desc1: 1 on page(s) 1
  // price1: 1 on page(s) 1
  // amount1: 1 on page(s) 1
  // qty2: 1 on page(s) 1
  // desc2: 1 on page(s) 1
  // price2: 1 on page(s) 1
  // amount2: 1 on page(s) 1
  // subtotal: 1 on page(s) 1
  // taxRate: 1 on page(s) 1
  // tax: 1 on page(s) 1
  // total: 1 on page(s) 1
  // Wrote qa_output/invoice_filled.pdf
}