In Flutter 3.0, the Qr Code Scanner is giving an error

Question

I am updating an old project. This qr code scanner is giving an error.The project had previously run on flutter 2.10. There are errors in Flutter 3.0.

import 'package:flutter/material.dart';
import 'package:qr_code_scanner/qr_code_scanner.dart';
import 'dart:io';
import 'package:flutter/foundation.dart';

void main() {
  runApp(const MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);

  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        
        primarySwatch: Colors.blue,
      ),
      home: const MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  const MyHomePage({Key? key, required this.title}) : super(key: key);


  final String title;

  @override
  State<MyHomePage> createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  final GlobalKey qrKey = GlobalKey(debugLabel: 'QR');
  Barcode? result;
  QRViewController? controller;

  // In order to get hot reload to work we need to pause the camera if the platform
  // is android, or resume the camera if the platform is iOS.
  @override
  void reassemble() {
    super.reassemble();
    if (Platform.isAndroid) {
      controller!.pauseCamera();
    } else if (Platform.isIOS) {
      controller!.resumeCamera();
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Column(
        children: <Widget>[
          Expanded(
            flex: 5,
            child: QRView(
              key: qrKey,
              onQRViewCreated: _onQRViewCreated,
            ),
          ),
          Expanded(
            flex: 1,
            child: Center(
              child: (result != null)
                  ? Text(
                  'Barcode Type: ${describeEnum(result!.format)}   Data: ${result!.code}')
                  : Text('Scan a code'),
            ),
          )
        ],
      ),
    );
  }

  void _onQRViewCreated(QRViewController controller) {
    this.controller = controller;
    controller.scannedDataStream.listen((scanData) {
      setState(() {
        result = scanData;
      });
    });
  }

  @override
  void dispose() {
    controller?.dispose();
    super.dispose();
  }
}

Error

Warning: unexpected element (uri:"", local:"base-extension"). Expected elements are <{}codename>,<{}layoutlib>,<{}api-level>
/C:/src/flutter/.pub-cache/hosted/pub.dartlang.org/qr_code_scanner-0.7.0/lib/src/qr_code_scanner.dart:68:20: Warning: Operand of null-aware operation '!' has type 'WidgetsBinding' which excludes null.
 - 'WidgetsBinding' is from 'package:flutter/src/widgets/binding.dart' ('/C:/src/flutter/packages/flutter/lib/src/widgets/binding.dart').
    WidgetsBinding.instance!.addObserver(_observer);
                   ^
/C:/src/flutter/.pub-cache/hosted/pub.dartlang.org/qr_code_scanner-0.7.0/lib/src/qr_code_scanner.dart:86:20: Warning: Operand of null-aware operation '!' has type 'WidgetsBinding' which excludes null.
 - 'WidgetsBinding' is from 'package:flutter/src/widgets/binding.dart' ('/C:/src/flutter/packages/flutter/lib/src/widgets/binding.dart').
    WidgetsBinding.instance!.removeObserver(_observer);
                   ^
e: C:\src\flutter\.pub-cache\hosted\pub.dartlang.org\qr_code_scanner-0.7.0\android\src\main\kotlin\net\touchcapture\qr\flutterqr\QRView.kt: (23, 1): Class 'QRView' is not abstract and does not implement abstract member public abstract fun onRequestPermissionsResult(p0: Int, p1: Array<(out) String!>, p2: IntArray): Boolean defined in io.flutter.plugin.common.PluginRegistry.RequestPermissionsResultListener
e: C:\src\flutter\.pub-cache\hosted\pub.dartlang.org\qr_code_scanner-0.7.0\android\src\main\kotlin\net\touchcapture\qr\flutterqr\QRView.kt: (216, 26): Null can not be a value of a non-null type String
e: C:\src\flutter\.pub-cache\hosted\pub.dartlang.org\qr_code_scanner-0.7.0\android\src\main\kotlin\net\touchcapture\qr\flutterqr\QRView.kt: (247, 26): Null can not be a value of a non-null type String
e: C:\src\flutter\.pub-cache\hosted\pub.dartlang.org\qr_code_scanner-0.7.0\android\src\main\kotlin\net\touchcapture\qr\flutterqr\QRView.kt: (310, 5): 'onRequestPermissionsResult' overrides nothing
e: C:\src\flutter\.pub-cache\hosted\pub.dartlang.org\qr_code_scanner-0.7.0\android\src\main\kotlin\net\touchcapture\qr\flutterqr\QRViewFactory.kt: (10, 1): Class 'QRViewFactory' is not abstract and does not implement abstract base class member public abstract fun create(p0: Context?, p1: Int, p2: Any?): PlatformView defined in io.flutter.plugin.platform.PlatformViewFactory
e: C:\src\flutter\.pub-cache\hosted\pub.dartlang.org\qr_code_scanner-0.7.0\android\src\main\kotlin\net\touchcapture\qr\flutterqr\QRViewFactory.kt: (13, 5): 'create' overrides nothing

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':qr_code_scanner:compileDebugKotlin'.
> Compilation error. See log for more details

* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.

* Get more help at https://help.gradle.org

BUILD FAILED in 21s
Running Gradle task 'assembleDebug'...                             22.5s
Exception: Gradle task assembleDebug failed with exit code 1

flutter doctor -v

[√] Flutter (Channel stable, 3.0.0, on Microsoft Windows [Version 10.0.19043.1645], locale en-US)
    • Flutter version 3.0.0 at C:\src\flutter
    • Upstream repository https://github.com/flutter/flutter.git
    • Framework revision ee4e09cce0 (2 days ago), 2022-05-09 16:45:18 -0700
    • Engine revision d1b9a6938a
    • Dart version 2.17.0
    • DevTools version 2.12.2

Checking Android licenses is taking an unexpectedly long time...[√] Android toolchain - develop for Android devices (Android SDK version 32.1.0-rc1)
    • Android SDK at C:\Users\User\AppData\Local\Android\sdk
    • Platform android-32, build-tools 32.1.0-rc1
    • Java binary at: C:\Program Files\Android\Android Studio\jre\bin\java
    • Java version OpenJDK Runtime Environment (build 11.0.11+9-b60-7590822)
    • All Android licenses accepted.

[√] Chrome - develop for the web
    • Chrome at C:\Program Files (x86)\Google\Chrome\Application\chrome.exe

[√] Visual Studio - develop for Windows (Visual Studio Professional 2022 17.1.3)
    • Visual Studio at C:\Program Files\Microsoft Visual Studio\2022\Professional
    • Visual Studio Professional 2022 version 17.1.32328.378
    • Windows 10 SDK version 10.0.19041.0

[√] Android Studio (version 2021.1)
    • Android Studio at C:\Program Files\Android\Android Studio
    • Flutter plugin can be installed from:
       https://plugins.jetbrains.com/plugin/9212-flutter
    • Dart plugin can be installed from:
       https://plugins.jetbrains.com/plugin/6351-dart
    • Java version OpenJDK Runtime Environment (build 11.0.11+9-b60-7590822)

[√] VS Code (version 1.67.1)
    • VS Code at C:\Users\User\AppData\Local\Programs\Microsoft VS Code
    • Flutter extension version 3.40.0

[√] Connected device (5 available)
    • SM T500 (mobile)        • R9AR702P83X   • android-arm64  • Android 11 (API 30)
    • sdk gphone x86 (mobile) • emulator-5554 • android-x86    • Android 11 (API 30) (emulator)
    • Windows (desktop)       • windows       • windows-x64    • Microsoft Windows [Version 10.0.19043.1645]
    • Chrome (web)            • chrome        • web-javascript • Google Chrome 101.0.4951.54
    • Edge (web)              • edge          • web-javascript • Microsoft Edge 101.0.1210.39

[√] HTTP Host Availability
    • All required HTTP hosts are available

• No issues found!

What should I do to make it work? Before everything was fine, I updated my project to the latest version of flutter and now I get this error.

Solution 1

You can directly import the library in this way:

 qr_code_scanner:
  git:
   url: https://github.com/xeinebiu/qr_code_scanner.git
   ref: fix_break_changes_platform

Solution 2

Downgrade flutter to the previous version "flutter downgrade" until an upgrade to flutter 3.0.0 is provided by the owners of all packages you are using in your project.

Updates: version 1.0.0 with these fixes is released. check https://github.com/juliuscanute/qr_code_scanner/issues/532 hope u mark also this as correct answer

Solution 3

This library doesn't work in Flutter 3.0.

Alternative => mobile_scanner