Dart Requires Chilkat v11.7.0+

Replace the Second (or Every) Occurrence of a Label in a PDF

See more PDF Text Replacement Examples

Demonstrates the "occurrence" member of a label entry. By default the first occurrence of a label, in reading order across the selected pages, is replaced; "occurrence" can be a number for the nth, or "all" for every occurrence. The invoice template has "Ref:" twice. Dart

import 'package:chilkat/chilkat.dart';

void main() {
  // 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();
  try {
    pdf.loadFile('qa_data/pdf/invoice_template.pdf');
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  final json = CkJsonObject();
  final jsonOut = CkJsonObject();

  // This template's {{placeholders}} are not being filled here: "keep" leaves them as they are
  // (the default, "error", would refuse to apply while a placeholder on the page has no value).
  json.updateString('unusedPlaceholders', 'keep');

  // "Ref:" appears twice on the page (A-1 near the top, A-2 below the totals).
  // The default replaces the first occurrence only.
  json.updateString('labels[0].label', 'Ref:');
  json.updateString('labels[0].value', 'B-7');
  try {
    pdf.textReplace('check', json, jsonOut);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  print('default: ${jsonOut.intOf('replacements[0].count')} occurrence replaced');

  // The second occurrence only.
  json.updateString('labels[0].occurrence', '2');
  try {
    pdf.textReplace('check', json, jsonOut);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  print('occurrence 2: ${jsonOut.intOf('replacements[0].count')} occurrence replaced');

  // Every occurrence.
  json.updateString('labels[0].occurrence', 'all');
  try {
    pdf.textReplace('apply', json, jsonOut);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  print('occurrence all: ${jsonOut.intOf('replacements[0].count')} occurrences replaced');

  try {
    pdf.writeFile('qa_output/invoice_refs.pdf');
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // Sample output:

  // default: 1 occurrence replaced
  // occurrence 2: 1 occurrence replaced
  // occurrence all: 2 occurrences replaced
}