Dart Requires Chilkat v11.7.0+

Get a PDF Field Value by its Label (Value to the Right)

See more PDF Text Extraction Examples

Demonstrates the "label" option, which captures the text that belongs to a caption such as "Invoice Number:" without needing coordinates. With labelValue "right", the value is the rest of the label's line. Label matching ignores case, extra spaces and a trailing colon. 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 invoice used in this example is available at invoice_labels.pdf

  final pdf = CkPdf();
  try {
    pdf.loadFile('qa_data/pdf/invoice_labels.pdf');
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

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

  // The invoice has lines such as "Invoice Number:   INV-2026-0412".
  // The label option restricts the "text" operation to the text belonging to the label.
  json.updateString('label', 'Invoice Number');

  // "right" means the value is the rest of the label's line.
  // (The default, "auto", uses the rest of the line if there is text there, otherwise the block below.)
  json.updateString('labelValue', 'right');

  try {
    pdf.extractText('text', json, jsonOut);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // The value is returned as the text.
  print('Invoice Number: ${jsonOut.stringOf('text')}');

  // The labelMatches array tells where the label was found and how it appeared in the PDF.
  print('Found on page ${jsonOut.intOf('labelMatches[0].page')} as "${jsonOut.stringOf('labelMatches[0].label')}"');

  // Matching ignores case and the trailing colon, so these all work:
  json.updateString('label', 'CUSTOMER:');
  try {
    pdf.extractText('text', json, jsonOut);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  print('Customer: ${jsonOut.stringOf('text')}');

  json.updateString('label', 'due date');
  try {
    pdf.extractText('text', json, jsonOut);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  print('Due Date: ${jsonOut.stringOf('text')}');

  // The totals at the foot of the invoice are right-aligned labels with the amount beside them.
  json.updateString('label', 'Total Due');
  try {
    pdf.extractText('text', json, jsonOut);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  print('Total Due: ${jsonOut.stringOf('text')}');

  // A label that is not found is not an error.  The text is empty, labelMatches is empty,
  // and the quality report has an issue with the code "labelNotFound".
  json.updateString('label', 'Tracking Number');
  try {
    pdf.extractText('text', json, jsonOut);
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  if (jsonOut.sizeOfArray('labelMatches') == 0) {
    print('Tracking Number: (not found) ${jsonOut.stringOf('quality.pages[0].issues[0].code')}');
  }

  // Sample output:

  // Invoice Number: INV-2026-0412
  // Found on page 1 as "Invoice Number:"
  // Customer: Northwind Traders
  // Due Date: April 13, 2026
  // Total Due: $1,234.53
  // Tracking Number: (not found) labelNotFound
}