escamoteur / get_it_mixin Goto Github PK

Starting a proofreading thread to consolidate errors and suggestions for improvements.

Hi @escamoteur, since upgrading to Flutter 2.2.2 and get_it_mixin 3.1.3, I'm noticing the following error when debugging my app:

../../../../.pub-cache/hosted/pub.dartlang.org/get_it_mixin-3.1.3/lib/src/mixin_state.dart:495:7: Warning: Operand of null-aware operation '!' has type 'void Function(BuildContext, AsyncSnapshot<R?>, void Function())' which excludes null.
 - 'BuildContext' is from 'package:flutter/src/widgets/framework.dart' ('../../../../fvm/versions/stable/packages/flutter/lib/src/widgets/framework.dart').
 - 'AsyncSnapshot' is from 'package:flutter/src/widgets/async.dart' ('../../../../fvm/versions/stable/packages/flutter/lib/src/widgets/async.dart').
      handler!(_element!, watch.lastValue!, watch.dispose);
      ^

Here's the referenced code in mixin_state:

    watch.lastValue = AsyncSnapshot<R?>.withData(
        ConnectionState.waiting, _initialValue ?? initialValueProvider?.call());
    if (executeImmediately) {
      handler!(_element!, watch.lastValue!, watch.dispose);
    }

    return watch.lastValue!;
  }

Thanks!

Obviously there is an error in readme in the following piece of code

String _emailAddress;
set country(String val) {
  _emailAddress = val;
  notifyListeners();
}

there should be

set emailAddress(String val) { ...

This is not a bug report, rather a request or a question on how to achieve a certain setup.

I would like to use get_it_mixin in a way that makes it possible that each instance of a widget has its own "view model" (state), backed by get_it_mixin.

So when my widget gets created, my view model object should be created in a one-to-one mapping. Here is where I run into problems registering them as singletons with the global GetIt, since it would give me the same view model instance each time.

I have experimented with pushScope but I'm not sure if that is the correct path.

The other idea is that my widget creates it own GetIt-instance but then the watch calls all work with the global GetIt instance, so that breaks.

Any ideas on how to do this? Also, am I doing something that seems completely wrong?
Any advice appreciated. Cheers!

[EDIT]
The same problem formulation and a solution with Riverpod

After reading the docs about 4 times I cannot for the life of me figure out what the difference between these are.

There are no examples in the example code.

Does this support restoration stuff like hydrated_bloc package?

I opened this one in flutter_command, but it turns out to be an issue with get_it_mixin. It is caused by registerHandler using watchX internally. This causes a runtime error.

I found a situation that causes an error and it isn't clear why it's an error.

If I use a
registerHandler((StringManager sm) => sm.transformString, (context, name, _) => print(name));
before
var message2 = watchX((StringManager sm) => sm.transformString);

this causes an error. However if I reverse the order of the statements, there is no error & everything works just fine.

What's going on here?

Thank you!

import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';
import 'package:flutter_command/flutter_command.dart';
import 'package:get_it/get_it.dart';
import 'package:get_it_mixin/get_it_mixin.dart';

void main() {
  var sm = StringManager();
  GetIt.I.registerSingleton<StringManager>(sm);
  sm.loadStringCommand.execute();

  runApp(MaterialApp(home: MyApp()));
}

class StringManager {
  Command<void, String> loadStringCommand;
  ValueListenable<String> transformString;

  StringManager() {
    loadStringCommand =
        Command.createAsync<void, String>(_stringService, 'initial');

    transformString =
        loadStringCommand.map<String>((result) => result.toUpperCase());
  }

//TODO why is 'void x' needed as a parameter?
  Future<String> _stringService(void x) async {
    await Future.delayed(Duration(seconds: 2));
    return 'thank you for waiting';
  }
}

class MyApp extends StatelessWidget with GetItMixin {
  @override
  Widget build(BuildContext context) {


    var message = watchX((StringManager sm) => sm.loadStringCommand);
    var message2 = watchX((StringManager sm) => sm.transformString);

    registerHandler((StringManager sm) => sm.transformString,
            (context, name, _) => print(name));

    return Scaffold(
      appBar: AppBar(
        title: Text('hello'),
      ),
      body: Column(
        children: [Text(message), Text(message2)],
      ),
    );
  }
}

I have a new page that initializes its dependency in the build method like so:

  Widget build(BuildContext context) {
    pushScope(
        init: (locator) => locator.registerSingleton(PreferencesViewModel()));

    return Scaffold(
      body: SafeArea(child: _buildContent(context)),
    );
  }

I get the following exception after popping the page:

Another exception was thrown: You already have used the scope name null

I/flutter (14985): 'package:get_it/get_it_impl.dart':
I/flutter (14985): Failed assertion: line 732 pos 7: '_scopes.firstWhereOrNull((x) => x.name == scopeName) == null'
I/flutter (14985): 
I/flutter (14985): The relevant error-causing widget was:
I/flutter (14985):   PreferencesPage
I/flutter (14985):   file:///hello_world/app/preferences_page.dart:14:56
I/flutter (14985): 
I/flutter (14985): When the exception was thrown, this was the stack:
I/flutter (14985): #2      _GetItImplementation.pushNewScope (package:get_it/get_it_impl.dart:732:7)
I/flutter (14985): #3      _MixinState.pushScope (package:get_it_mixin/src/mixin_state.dart:540:15)
I/flutter (14985): #4      GetItMixin.pushScope (package:get_it_mixin/src/mixin.dart:240:20)
I/flutter (14985): #5      PreferencesPage.build (package:serqit_app/ui/preferences/preferences_page.dart:18:5)
I/flutter (14985): #6      StatelessElement.build (package:flutter/src/widgets/framework.dart:4648:28)
I/flutter (14985): #7      _GetItElement.build (package:get_it_mixin/src/elements.dart:16:18)
I/flutter (14985): #8      ComponentElement.performRebuild (package:flutter/src/widgets/framework.dart:4574:15)
I/flutter (14985): #9      Element.rebuild (package:flutter/src/widgets/framework.dart:4267:5)
I/flutter (14985): #10     ComponentElement._firstBuild (package:flutter/src/widgets/framework.dart:4553:5)
I/flutter (14985): #11     ComponentElement.mount (package:flutter/src/widgets/framework.dart:4548:5)
I/flutter (14985): #12     _GetItElement.mount (package:get_it_mixin/src/elements.dart:9:11)

I am not sure what I am doing wrong if anything.

Hi escamoteur,

I do not know if this is the right package or should I post this issue on flutter_command repo. But I think the issue is with maybe here.

Let us take a simple counter example. I register a singleton and then when I try to use the watchX command, I get an error stating void is not a valid return type.
however, the return type is a string . eg. Command<void, String> so it is not void. So why cannot watchX get the return type correct. Am I doing something wrong.?

example code .

import 'package:get_it/get_it.dart';
import 'package:get_it_mixin/get_it_mixin.dart';
import 'package:flutter_command/flutter_command.dart';
import 'package:flutter/material.dart';

final GetIt locator = GetIt.instance;

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

void setup() {
  locator.registerSingleton<CounterManager>(
    CounterManager(),
  );
}

class CounterManager {
  int counter = 0;
  Command<void, String> incrementCounterCommand;
  CounterManager() {
    incrementCounterCommand = Command.createSyncNoParam(() {
      counter++;
      return counter.toString();
    }, '0');

  }
}

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      title: 'GetIt Mixins',
      theme: ThemeData.light().copyWith(primaryColor: Color(0xFFe13133)),
      home: GetItMixinsScreen(),
    );
  }
}

class GetItMixinsScreen extends StatelessWidget with GetItMixin {
  @override
  Widget build(BuildContext context) {
    final counter  =
        watchX((CounterManager x) => x.incrementCounterCommand.execute());
   
    return Scaffold(
      appBar: AppBar(
        title: Text("Counter"),
      ),
      body: Container(
        child: SafeArea(
          child: Padding(
            padding: const EdgeInsets.all(8.0),
            child: Container(
              padding: EdgeInsets.all(8.0),
              decoration: kWhiteBackground,
              child: Column(
                crossAxisAlignment: CrossAxisAlignment.start,
                children: [
                  Text(
                    "Counter",
                    style: Theme.of(context).textTheme.headline4,
                  ),

                ],
              ),
            ),
          ),
        ),
      ),
    );
  }
}

flutter pubspec.yaml

flutter_command: ^2.0.1
  functional_listener: ^2.0.2
  get_it_mixin: ^3.1.3
```



flutter doctor results 

Doctor summary (to see all details, run flutter doctor -v):
[✓] Flutter (Channel stable, 2.8.1, on macOS 12.1 21C52 darwin-x64, locale en-DK)
[✓] Android toolchain - develop for Android devices (Android SDK version 32.0.0)
[✓] Xcode - develop for iOS and macOS (Xcode 13.2.1)
[✓] Chrome - develop for the web
[✓] Android Studio (version 2020.3)
[✓] VS Code (version 1.63.2)
[✓] Connected device (2 available)

I have a simple question. The Readme shows this example:

class UserModel extends ChangeNotifier {
  get name = _name;
  String _name = '';
  set name(String value){
    _name = value;
    notifyListeners();
  }
  ...
}

Why create a getter that points to _name? Isn't that redundant to just using name?

class UserModel extends ChangeNotifier {
  String name = '';
  set name(String value){
    name = value;
    notifyListeners();
  }
  ...
}

Can you help me understand the need for a getter alongside a property? Thanks! 😊

We are using ort for automatic software compliance checks.

get_it_mixin is one of our dependencies and we use it in version 4.2.2. Now, ort fails in scanning this repo, as this version is not tagged on GitHub.

Could you please add the missing tag "4.2.2" to GitHub and keep these tags in sync with upcoming releases?

Does getItMixin works on web @escamoteur ? Because in the Package it says yes.. so i brought this issue.

I have a project and i use getIt+getItMixin within it.
It works all good on mobile, but when trying to execute on web it gives me these errors:

I'm using:

get_it: ^6.0.0-nullsafety.2
get_it_mixin: ^2.0.1

The following TypeErrorImpl was thrown building HomePage(dirty):
Expected a value of type 'LinkedList<_WatchEntry<Object, Object>>?', but got one of type 'LinkedList<_WatchEntry<Object, Object?>>'

The relevant error-causing widget was
HomePage
lib\main.dart:28
When the exception was thrown, this was the stack
C:/b/s/w/ir/cache/builder/src/out/host_debug/dart-sdk/lib/_internal/js_dev_runtime/private/ddc_runtime/errors.dart 236:49      throw_
C:/b/s/w/ir/cache/builder/src/out/host_debug/dart-sdk/lib/_internal/js_dev_runtime/private/ddc_runtime/errors.dart 84:3        castError
C:/b/s/w/ir/cache/builder/src/out/host_debug/dart-sdk/lib/_internal/js_dev_runtime/private/ddc_runtime/operations.dart 442:10  cast
C:/b/s/w/ir/cache/builder/src/out/host_debug/dart-sdk/lib/_internal/js_dev_runtime/private/ddc_runtime/types.dart 417:9        as
C:/b/s/w/ir/cache/builder/src/out/host_debug/dart-sdk/lib/collection/linked_list.dart 224:18                                   set [_list]

I saw that when using the GetItMixin or GetItStatefullWidgetMixin i have the same error even for the simpliest example.
See below a code sample that generate the errors.

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

final getIt = GetIt.instance;

void setup() async {
  getIt.registerSingleton<PlayerViewModel>(PlayerViewModel());
}

class MyApp extends StatelessWidget {
  const MyApp();

  @override
  Widget build(BuildContext context) {
    SystemChrome.setEnabledSystemUIOverlays([]);
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      title: 'Flutter Demo',
      home: HomePage(),
    );
  }
}


class HomePage extends StatelessWidget with GetItMixin {
  @override
  build(BuildContext context) {
    int count = 0;

    final name = watchOnly((PlayerViewModel v) => v.name);
    // final name = getIt<PlayerViewModel>().name;

    return Scaffold(
      body: Container(
        color: Colors.deepPurple,
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            Text(
              name,
              style: TextStyle(
                color: Colors.red,
              ),
            ),
            ElevatedButton(
                onPressed: () {
                  count++;
                  getIt<PlayerViewModel>().name = 'X $count';
                },
                child: Text('ok'))
          ],
        ),
      ),
    );
  }
}


import 'package:flutter/foundation.dart';

class PlayerViewModel extends ChangeNotifier {
  String _name = 'NAME TEST';
  String get name => _name;

  set name(String name) {
    _name = name;
    notifyListeners();
  }
}

If i change:
final name = watchOnly((PlayerViewModel v) => v.name);

for the code below it works good, and the page is rendered normally.
final name = getIt().name;

Edit.: adds the version of both packages.:

In contrast to other packages, get_it_mixin does not put the full license text in LICENSE, but only "MIT". This makes it hard to automate license extraction, e.g. for SBOM creation. Currently, I'm evaluation LicenseFinder, which stumbles upon this package and cannot extract its license.

https://pub.dev/packages/get_it/versions/6.0.0-nullsafety.2
https://github.com/dart-lang/sdk/wiki/Null-safety-migration-status

When using handlers, they cause the the component with the mixin to re-render on each "change".

Here's a simple example reproducing the issue

import 'dart:async';

import 'package:flutter/material.dart';
import 'package:get_it/get_it.dart';
import 'package:get_it_mixin/get_it_mixin.dart';

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget with GetItStatefulWidgetMixin {
  MyHomePage({Key? key, required this.title}) : super(key: key);
  final String title;

  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> with GetItStateMixin {
  int _counter = 0;

  @override
  Widget build(BuildContext context) {
    print('build');
    registerStreamHandler<AppModel, String>((x) => x.stream,
        (context, x, cancel) {
      print('handle stream');
    });
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            Text(
              'You have pushed the button this many times:',
            ),
            Text(
              '$_counter',
              style: Theme.of(context).textTheme.headline4,
            ),
          ],
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: () => get<AppModel>().streamController.add("event"),
        tooltip: 'Increment',
        child: Icon(Icons.add),
      ), // This trailing comma makes auto-formatting nicer for build methods.
    );
  }
}

final getIt = GetIt.instance;

void setup() {
  getIt.registerLazySingleton(() => AppModel());
}

class AppModel extends ChangeNotifier {
  // ignore: close_sinks
  final StreamController<String> streamController =
      StreamController<String>.broadcast();

  Stream<String> get stream => streamController.stream;
}

Notice that each button tap causes the build statement to be printed.

If WatchX is used inside a StreamBuilder, it does not update and never rebuilds the widget.

Hi my friends,

I recently published my new package watch_it, an overhauled version of the get_it_mixin but with a more intuitive and streamlined API. Porting an existing project using get_it_mixin is really easy and quick.

To better connect with my package users I know opened a Discord Server to support my packages https://discord.gg/ZHYHYCM38h

This package here won't be further maintained. You can continue using the latest version but I won't add new features or fix bugs.

1. Say I have a Value Notifier, controller and a widget (it's a simplified example)

import 'package:flutter/material.dart';
import 'package:get_it/get_it.dart';
import 'package:get_it_mixin/get_it_mixin.dart';

class FirstSampleNotifier extends ValueNotifier<Model?> {
  FirstSampleNotifier() : super(null);
}

class Model {}

class FirstController {
  final FirstSampleNotifier firstSampleNotifier;

  FirstController(this.firstSampleNotifier);
}

class FirstWidget extends StatelessWidget with GetItMixin {
  FirstWidget({super.key});

  final firstController = GetIt.I<FirstController>();

  @override
  Widget build(BuildContext context) {
    final model = watch(target: firstController.firstSampleNotifier);
    return const Scaffold();
  }
}

The type of model in the build method isn't inferred (it's dynamic), unless I do instead:
final model = watch<ValueNotifier<Model?>, Model?>(target: firstController.firstSampleNotifier);
then it's correctly identified as being Model?.
Is there something I'm missing or is this long way of putting it the only way when the Value Notifier type is nullable?

2. Similar example with a value notifier whose value is bool and it isn't nullable:

import 'package:flutter/material.dart';
import 'package:get_it/get_it.dart';
import 'package:get_it_mixin/get_it_mixin.dart';

class SecondSampleNotifier extends ValueNotifier<bool> {
  SecondSampleNotifier() : super(false);
}

class SecondController {
  final SecondSampleNotifier secondSampleNotifier;

  SecondController(this.secondSampleNotifier);
}

class SecondWidget extends StatelessWidget with GetItMixin {
  SecondWidget({super.key});

  final secondController = GetIt.I<SecondController>();

  @override
  Widget build(BuildContext context) {
    final boolValue = watch(target: secondController.secondSampleNotifier);
    return const Scaffold();
  }
}

Again, the type of boolValue isn't inferred, I have to write instead
final bool boolValue = watch(target: secondController.secondSampleNotifier);
which isn't a big thing, but am I missing something here? Is there some syntactic sugar I don't see?

I am trying to use registerHandler to display the gallery permission dialog whenever the user clicks to open the gallery. However, I am having trouble integrating and using it properly.

The problem is that it only works the first time, and subsequent calls to isGalleryPermissionDenied.value = true; do not trigger notifyListeners as expected. I have tried manually calling isGalleryPermissionDenied.notifyListeners(), but this causes it to trigger twice initially.

How can I properly use registerHandler to display dialog if gallery is denied and trigger notifyListeners as expected?

class ProfilePhotoScreen extends StatelessWidget with GetItMixin {
  ProfilePhotoScreen({Key? key}) : super(key: key);

  void onGalleryPermissionDenied(context, newValue, cancel) {
    showPermissionDeniedDialogNew(...);
  }
  
  @override
  Widget build(BuildContext context) {
    registerHandler((ProfilePhotoViewModel vm) => vm.isGalleryPermissionDenied, onGalleryPermissionDenied);
    ...
  }
}

class ProfilePhotoViewModel with Disposable {
  ProfilePhotoViewModel({required this.imageService});
  
  ValueNotifier<bool> isGalleryPermissionDenied = ValueNotifier(false);
  
   void pickImage(BuildContext context) {
    ...
    isGalleryPermissionDenied.value = true;
  }
}

watchStream might be broken because it tries to return a AsyncSnapshot instead of the

I am trying to watch the Firebase Auth.
final User user = watchStream((AuthService auth) => auth.user, null).data;

The Stream in AuthService is
Stream<User> get user => _auth.authStateChanges();

The following error is thrown:
type 'AsyncSnapshot<User>' is not a subtype of type 'User'

Error location:

Dart Unhandled Exception: type 'AsyncSnapshot' is not a subtype of type 'User' of 'value', stack trace: #0 _WatchEntry.lastValue= (package:get_it_mixin/src/mix_in.dart)
_MixinState.watchStream. (package:get_it_mixin/src/mix_in.dart:793:15)

I installed latest versions of AndroidStudio, Flutter, plugins etc. Since I had different versions of AndroidStudio I cleaned up everything and re-installed from scratch. I started replacing Stateful with Stateless Widgets and added get_it_mixin. When building the project I get the following error:

Launching lib/main.dart on iPhone 13 in debug mode...
Running Xcode build...
Xcode build done.                                           10.5s
Debug service listening on ws://127.0.0.1:53118/H_LQeT1mgxM=/ws
Syncing files to device iPhone 13...
../../../../Applications/flutter/.pub-cache/hosted/pub.dartlang.org/get_it_mixin-3.1.3/lib/src/mixin_state.dart:495:7: Warning: Operand of null-aware operation '!' has type 'void Function(BuildContext, AsyncSnapshot<R?>, void Function())' which excludes null.
 - 'BuildContext' is from 'package:flutter/src/widgets/framework.dart' ('../../../../Applications/flutter/packages/flutter/lib/src/widgets/framework.dart').
 - 'AsyncSnapshot' is from 'package:flutter/src/widgets/async.dart' ('../../../../Applications/flutter/packages/flutter/lib/src/widgets/async.dart').
      handler!(_element!, watch.lastValue!, watch.dispose);
      ^

The app starts but does not work since I implemented get_it_mixin on my home screen.

It happens also with Android Simulator, e.g. Pixel 4. Flutter doctor does not report any issues:

[Google] flutter doctor
Doctor summary (to see all details, run flutter doctor -v):
[✓] Flutter (Channel stable, 2.5.3, on macOS 11.6.1 20G224 darwin-x64, locale en-CH)
[✓] Android toolchain - develop for Android devices (Android SDK version 31.0.0)
[✓] Xcode - develop for iOS and macOS
[✓] Chrome - develop for the web
[✓] Android Studio (version 2020.3)
[✓] VS Code (version 1.62.3)
[✓] Connected device (2 available)

• No issues found!

I tried flutter clean but that didn't help.

Any idea what is wrong here?

Hi guys, thanks for this amazing package. Let me try to explain my doubt:

I have the follow class:

class EditProfileManager extends ChangeNotifier {
  final SupabaseAuthService _api;

  EditProfileManager(this._api);

  final List<String> _photosPaths = List.filled(5, '');

  get photos => _photosPaths;

  void getCurrentPhotos() {
    appManager.currentProfile.photos.asMap().forEach((index, value) {
      _photosPaths[index] = value;
    });
    notifyListeners();
  }

  void updatePhoto(index, String path) {
    _photosPaths[index] = path;
    notifyListeners();
  }
}

I update some values of my _photosPaths, and tried to rebuild my widget with this new value, but nothing happens ( only if i manually refresh ).
I watching the changes like that:

class GridPhotosViewer extends StatelessWidget with GetItMixin {
  GridPhotosViewer({super.key});

  @override
  Widget build(BuildContext context) {
    final photosPaths = watchX((EditProfileManager m) => m.photos);

    return Container(
      padding: const EdgeInsets.all(8),
      child: StaggeredGrid.count(
        axisDirection: AxisDirection.down,
        crossAxisCount: 4,
        mainAxisSpacing: 4,
        crossAxisSpacing: 4,
        children: List.generate(photosPaths.length, (index) {

I'm doing something wrong ?

I have a custom object Strokes which implements changeNotifier.
I watch it with:

final Strokes strokes = watchOnly((Strokes s) => s);

This object has two methods deleteLastStroke():

    // get all strokes except for the last one
    var p = _path.computeMetrics().take(_path.computeMetrics().length - 1);
    var newPath = Path();
    // copy the strokes to a new Path
    p.forEach((element) {
      newPath.addPath(element.extractPath(0, double.infinity), Offset.zero);
    });
    _path = newPath;

    decrementStrokeCount();

    notifyListeners();

and deleteAllStrokes():

    _path.reset();
    _strokeCount = 0;

    notifyListeners();

Both of them call notifyListeners() however only deleteAllStrokes() triggeres a rebuild of the UI.
When calling deleteLastStroke() nothing happens. However when doing:

deleteLastStroke();
setState((){});

The UI rebuilds and everything works as expected.

If I am doing something wrong could you please point me in the right direction?

Imagine you have an object inside GetIt registered that implements ValueListenableBuilder

prolly ought to be

Imagine you have an object inside GetIt registered that implements ValueListenable

Let's suppose the structure below of a Viewmodel

import 'package:dio/dio.dart';
import 'package:flutter/foundation.dart';
import 'package:injectable/injectable.dart';

@Injectable()
class MyViewmodel {
  final name = ValueNotifier<String?>(null);

  bool _initialized = false;

  Future<void> initialize() async {
    if (_initialized) return;

    final resp = await Dio().get('https://jsonplaceholder.typicode.com/users/2');
    name.value = resp.data['name'];

    _initialized = true;
  }
}

But on the build method it is never anything than null... Do every viewmodel need to be stored as singleton on GetIt?