Dart Requires Chilkat v11.7.0+

Handle QR Code Errors

See more QR Code Examples

Demonstrates what happens when a request is refused. QrCode returns false and the response holds errors[0] with three members: a code that does not change between versions, the path of the request member at fault (a JSON Pointer such as /encoding/qr/version), and a message. Requests are checked strictly, so a misspelled option is an error rather than being silently ignored. LastErrorText has the same information in more detail. 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.

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

  // 1. A misspelled option: "moduleSise" for "moduleSize".
  json.updateString('payload.text', 'https://www.chilkatsoft.com/');
  json.updateInt('render.moduleSise', 8);
  try {
    fmt.qrCode('generate', json, jsonOut);
  } on ChilkatException {
    print('code: ${jsonOut.stringOf('errors[0].code')}');
    print('path: ${jsonOut.stringOf('errors[0].path')}');
    print('message: ${jsonOut.stringOf('errors[0].message')}');
  }

  // 2. A value out of range: QR versions are 1 to 40.
  json.clear();
  json.updateString('payload.text', 'https://www.chilkatsoft.com/');
  json.updateInt('encoding.qr.version', 41);
  try {
    fmt.qrCode('generate', json, jsonOut);
  } on ChilkatException {
    print('code: ${jsonOut.stringOf('errors[0].code')}');
    print('path: ${jsonOut.stringOf('errors[0].path')}');
    print('message: ${jsonOut.stringOf('errors[0].message')}');
  }

  // 3. Too much data: this text does not fit a version 1 symbol.
  json.clear();
  json.updateString('payload.text', 'https://www.chilkatsoft.com/barcode_overview.asp');
  json.updateInt('encoding.qr.version', 1);
  try {
    fmt.qrCode('generate', json, jsonOut);
  } on ChilkatException {
    print('code: ${jsonOut.stringOf('errors[0].code')}');
    print('path: ${jsonOut.stringOf('errors[0].path')}');
    print('message: ${jsonOut.stringOf('errors[0].message')}');
  }

  // A program can act on the code.
  if (jsonOut.stringOf('errors[0].code') == 'capacityExceeded') {
    print('The text is too long for the symbol size allowed.');
  }

  // Sample output:

  // code: unknownOption
  // path: /render/moduleSise
  // message: unknown option
  // code: outOfRange
  // path: /encoding/qr/version
  // message: the value is out of range
  // code: capacityExceeded
  // path: /payload
  // message: the payload does not fit the requested QR version at the requested error-correction level
  // The text is too long for the symbol size allowed.
}