Flutter Current

A simple, lightweight state management library for Flutter

Features

• Typed reactive properties for primitives, nullable values, lists, and maps.
• View-model-driven widgets with CurrentWidget and CurrentState.
• Application-wide shared state with Current.
• Issue-based validation that keeps localization in the widget layer.
• Text input binding with CurrentTextController, CurrentTextFormField, and CurrentTextField for form and non-form flows.
• Built-in busy state, change notifications, and event listeners for async flows.

Getting Started

In your Flutter project, add the dependency to your pubspec.yaml.

dependencies:
  current: ^3.0.0

Tip: It is highly recommended to install the Flutter Current extension in Visual Studio Code. It provides super helpful code snippets, commands, and Quick Fix actions to speed up your development workflow when using Flutter Current.

Quick Start

A small counter is still the fastest way to see the core pattern: keep state in a CurrentViewModel, list reactive properties in currentProps, and render that view model through a CurrentWidget.

counter_view_model.dart

import 'package:current/current.dart';

class CounterViewModel extends CurrentViewModel {
  final count = CurrentProperty.integer();

  void incrementCounter() {
    count.value += 1;
  }

  @override
  Iterable<CurrentProperty> get currentProps => [count];
}

counter_page.dart

import 'package:current/current.dart';
import 'package:flutter/material.dart';

class CounterPage extends CurrentWidget<CounterViewModel> {
  const CounterPage({super.key, required super.viewModel});

  @override
  CurrentState<CounterPage, CounterViewModel> createCurrent() {
    return _CounterPageState(viewModel);
  }
}

class _CounterPageState extends CurrentState<CounterPage, CounterViewModel> {
  _CounterPageState(super.viewModel);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: const Text('Current Example')),
      body: Center(
        child: Text('Count: ${viewModel.count}'),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: viewModel.incrementCounter,
        child: const Icon(Icons.add),
      ),
    );
  }
}

main.dart

import 'package:flutter/material.dart';

void main() => runApp(const MyApp());

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Current State Example',
      home: CounterPage(
        viewModel: CounterViewModel(),
      ),
    );
  }
}

This keeps business logic out of the widget tree without introducing a second state object. When any property in currentProps changes, the matching CurrentState rebuilds automatically.

Forms And Validation

Current validation is issue-based. Rules return CurrentValidationIssue, not display strings. That keeps validation logic locale-agnostic and lets widgets resolve the final text using whatever localization system the app already uses.

profile_view_model.dart

import 'package:current/current.dart';

class ProfileViewModel extends CurrentViewModel {
  final displayName = CurrentProperty.string();
  final age = CurrentProperty.integer();

  // Can define your validation rules in the view model
  // or in a separate validation focused file if that keeps things cleaner and/or easier to test.

  CurrentFieldValidation<String> displayNameValidation(CurrentStringProperty displayName, AppLocalizations intl) {
    return displayName.createValidation(rules: [_displayNameNotEmpty(intl)]);
  }

  CurrentValidationRule<String> _displayNameNotEmpty(AppLocalizations intl) {
    return (value) => value.trim().isEmpty
        ? CurrentValidationIssue.message(intl.displayNameRequired)
        : null;
  }

  CurrentFieldValidation<int> ageValidation(CurrentIntegerProperty age) {
    return age.createValidation(rules: [_userIsAdult()]);
  }

  CurrentValidationRule<int> _userIsAdult() {
    return (value) => value < 18
        ? const CurrentValidationIssue(
            'profile.age.minimum', // error code if localization is based on codes
            arguments: {'minimumAge': 18},
            fallbackMessage: 'Must be at least 18',
          )
        : null;
  }

  @override
  Iterable<CurrentProperty> get currentProps => [displayName, age];
}

profile_page.dart

import 'package:current/current.dart';
import 'package:flutter/material.dart';

class ProfilePage extends CurrentWidget<ProfileViewModel> {
  const ProfilePage({super.key, required super.viewModel});

  @override
  CurrentState<ProfilePage, ProfileViewModel> createCurrent() {
    return _ProfilePageState(viewModel);
  }
}

class _ProfilePageState extends CurrentState<ProfilePage, ProfileViewModel>
    with CurrentTextControllersLifecycleMixin {

  _ProfilePageState(super.viewModel);

  final _formKey = GlobalKey<FormState>();
  final displayNameController = CurrentTextController.string();
  final ageController = CurrentTextController.integer();

  @override
  void bindCurrentControllers() {
    // Bind each controller to its property, with an optional validation builder.
    // Once the controller is bound and assigned to a CurrentTextFormField,
    // value parsing, validation, state updates, and error visibility are automatically handled for you.

    displayNameController.bind(
      property: viewModel.displayName,
      lifecycleProvider: this,
      validationBuilder: (property, context) =>
        viewModel.displayNameValidation(property, AppLocalizations.of(context)),
    );

    ageController.bind(
      property: viewModel.age,
      lifecycleProvider: this,
      validationBuilder: (property, _) => viewModel.ageValidation(property),
      validationIssues: CurrentTextControllerValidationIssues(
        invalidValueIssueBuilder: _invalidAgeIssue, // Optional custom message for invalid values
      ),
    );
  }

  @override
  Widget build(BuildContext context) {
    return Form(
      key: _formKey,
      child: Column(
        children: [
          CurrentTextFormField<String>(
            controller: displayNameController,
            autovalidateMode: AutovalidateMode.onUserInteraction,
            decoration: const InputDecoration(labelText: 'Display name'),
          ),
          CurrentTextFormField<int>(
            controller: ageController,
            autovalidateMode: AutovalidateMode.onUserInteraction,
            validationTextResolver: _resolveIssueText,
            decoration: const InputDecoration(labelText: 'Age'),
          ),
          FilledButton(
            onPressed: () {
              if (_formKey.currentState?.validate() ?? false) {
                // Submit the form.
              }
            },
            child: const Text('Save profile'),
          ),
        ],
      ),
    );
  }

  static String? _resolveIssueText(CurrentValidationIssue issue) {
    switch (issue.code) {
      case 'profile.age.minimum':
        return 'Must be at least ${issue.arguments['minimumAge']} years old.';
      case 'profile.age.invalid':
        return 'Enter a valid whole number.';
      default:
        return issue.fallbackMessage;
    }
  }

  static CurrentValidationIssue _invalidAgeIssue(String value) {
    return const CurrentValidationIssue.invalidValue(
      code: 'profile.age.invalid',
      fallbackMessage: 'Enter a valid whole number.',
    );
  }
}

Choosing a field widget

Current exposes three field-integration paths. Pick the one that matches who owns your widget tree and validation UX.

• Use CurrentTextFormField when you are already inside a Form and want the shortest Current-specific wrapper.
• Use native TextFormField with controller.formValidator(...) when your app already has its own field wrapper or design-system component and you only want Current to provide binding plus validation bridging.
• Use CurrentTextField when you are not using Flutter Form widgets but still want Current-managed error visibility with AutovalidateMode-style behavior.

CurrentTextFormField<String>(
  controller: displayNameController,
  autovalidateMode: AutovalidateMode.onUserInteraction,
  validationTextResolver: _resolveIssueText,
  decoration: const InputDecoration(labelText: 'Display name'),
);

TextFormField(
  controller: ageController,
  autovalidateMode: AutovalidateMode.onUserInteraction,
  validator: ageController.formValidator(
    context: context,
    resolver: _resolveIssueText,
  ),
  decoration: const InputDecoration(labelText: 'Age'),
);

CurrentTextField<String>(
  controller: displayNameController,
  autovalidateMode: AutovalidateMode.onUserInteractionIfError,
  validationTextResolver: _resolveIssueText,
  decoration: const InputDecoration(labelText: 'Quick search'),
);

Key points:

• Register validation once, either by calling createValidation() directly or by supplying validationBuilder when binding a controller.
• Use CurrentValidationGroup.forProperties([...]) when you want grouped validation without separately listing validators.
• Use CurrentTextFormField for the shortest Form integration, native TextFormField with controller.formValidator(...) when your widget layer already exists, and CurrentTextField when you want Current-managed validation without a Form.
• Let widgets resolve issue text either through a resolver or through BuildContext when your localization API requires it.
• Use CurrentTextControllerValidationIssues for controller-generated parse or required-value failures.
• Validation rules can live in the widget, the view model, or in a separate plain-Dart helper file when that keeps a larger form easier to read.

Application Wide State Management

Use Current when you want a shared CurrentViewModel anywhere below a subtree, or across the whole app.

application_view_model.dart

import 'package:current/current.dart';

class ApplicationViewModel extends CurrentViewModel {
  final userName = CurrentProperty.nullableString();
  final signedIn = CurrentProperty.boolean();

  void signIn(String name) {
    userName.value = name;
    signedIn.value = true;
  }

  @override
  Iterable<CurrentProperty> get currentProps => [userName, signedIn];
}

main.dart

import 'package:current/current.dart';
import 'package:flutter/material.dart';

void main() => runApp(const MyApp());

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Current(
        ApplicationViewModel(),
        child: Builder(
          builder: (context) {
            final appViewModel = Current.viewModelOf<ApplicationViewModel>(context);
            final userName = appViewModel.userName.value;

            return Column(
              children: [
                Text('User: ${userName ?? 'Guest'}'),
                TextButton(
                  onPressed: () => appViewModel.signIn('Taylor'),
                  child: const Text('Sign In'),
                ),
              ],
            );
          },
        ),
      ),
    );
  }
}

Explore The Example App

The repository includes a larger showcase app in example/README.md. It demonstrates typed properties, form validation, controller binding, collection properties, busy state, custom events, and reference snippets in a single responsive mission-control UI.

Contributing

This is an open source project, and contributions are welcome. Please feel free to create a new issue if you encounter any problems, or submit a pull request. For community contribution guidelines, please review the Code of Conduct.

If submitting a pull request, please ensure the following standards are met:

1. Code files must be well formatted with dart format ..
2. Tests must pass with flutter test. New test cases to validate your changes are highly recommended.
3. Implementations must not add unnecessary project dependencies.
4. Project must contain zero warnings. Running flutter analyze must return zero issues.
5. Keep docstrings and README guidance up to date when public APIs change.

Additional information

This package has ZERO third-party package dependencies.

You can find the full API documentation here.

© 2026 Third Version Technology Ltd