dataflow 1.3.0

A reactive state management library for Flutter with a simple and intuitive API which allows you to build Flutter applications with ease.

DataFlow

Documentation

For detailed documentation, please visit DataFlow Documentation.

Introduction

DataFlow is a powerful and flexible state management library for Flutter applications. It provides a simple and intuitive way to manage the flow of data and handle asynchronous operations in your app. With DataFlow, you can easily define actions, track their status, and update your UI accordingly.

DataFlow is designed to be lightweight, efficient, and easy to use. It leverages the power of Dart streams and follows a reactive programming paradigm to ensure smooth data flow and seamless UI updates.

Key Features

• DataStore: Centralized state management for your application.
• DataAction: Define asynchronous operations as actions with customizable execution logic.
• DataSync: A widget that rebuilds its descendants based on the state of a DataStore.
• DataSyncNotifier: A widget that notifies listeners when specific DataActions occur.
• Middleware: Intercept and modify actions before and after execution.
• DataChain: You execute one action and based on its result you execute something else.

Comparison Table

Feature/Library	DataFlow	Flutter Bloc	Provider	Riverpod	Signal	GetX
Centralized State Management	Yes	Yes	No	Yes	No	Yes
Asynchronous Operations	Yes (DataAction)	Yes (Bloc)	No (requires FutureProvider)	Yes (StateNotifierProvider)	No	Yes
Reactive UI Updates	Yes (DataSync)	Yes (BlocBuilder)	Yes (Consumer)	Yes (ConsumerWidget)	Yes (Reactive Programming)	Yes (Obx)
Middleware Support	Yes	Yes	No	No	No	No
Ease of Use	High	Medium	High	Medium	Medium	High
Learning Curve	Low	High	Low	Medium	Medium	Low
Boilerplate Code	Low	High	Low	Medium	Low	Low
Built for Flutter	Yes	Yes	Yes	Yes	Yes	Yes
Community Support	Growing	High	High	Growing	Growing	High
Performance	High	High	High	High	High	-

Getting Started

To start using DataFlow in your Flutter project, follow these steps:

1. Add the dataflow package to your pubspec.yaml file:

dependencies:
  dataflow: ^1.0.2

2. Import the package in your Dart code:

import 'package:dataflow/dataflow.dart';

3. Initialize DataFlow with a DataStore:

void main() {
  DataFlow.init(MyDataStore());
  runApp(MyApp());
}

4. Define your DataActions:

class FetchDataAction extends DataAction<MyDataStore> {
  @override
   execute() async {
    // Your data fetching logic here
    await Future.delayed(Duration(seconds: 2));
    print('Fetched Data');
  }
}

5. Use DataSync in your widgets:

class MyHomePage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('DataFlow Example')),
      body: DataSync<MyDataStore>(
        actions: {FetchDataAction},
        loadingBuilder: (context) {
            return const Center(child: CircularProgressIndicator());
          },
        errorBuilder: (context, error) {
            return Center(child: Text('An error occurred: $error'));
          },
        builder: (context, store, hasData) {
          return LoginScreen();
        },
      ),
    );
  }
}

6. Trigger actions from your UI:

ElevatedButton(
  onPressed: () {
    FetchDataAction();
  },
  child: Text('Fetch Data'),
),

DataAction

A DataAction represents an asynchronous operation in your application. It encapsulates the execution logic and provides a way to track the status of the action.

To define a DataAction, create a class that extends the DataAction class and implement the execute method:

class FetchDataAction extends DataAction {
  @override
  dynamic execute() async {
    // Your data fetching logic here
    await Future.delayed(Duration(seconds: 2));
    print('Fetched Data');
  }
}

The execute method contains the actual logic for the action. It can perform any asynchronous operation, such as making API calls, querying a database, or processing data.

You can trigger a DataAction by calling it directly like:

FetchDataAction();

DataActions can also be chained together using the next method:

FetchDataAction().next(() => ProcessDataAction());

DataStore

A DataStore is a centralized repository for managing the state of your application. It extends the DataStore class and can hold any data relevant to your app.

To create a DataStore, define a class that extends DataStore:

class MyDataStore extends DataStore {
  // Your application state here
  String data = '';
}

You can access the DataStore from anywhere in your app using the DataFlow.getStore method:

final store = DataFlow.getStore<MyDataStore>();
or
final store = context.getStore<MyDataStore>();

DataFlow

DataFlow is the core class that manages the flow of actions and notifies listeners of state changes. It is initialized with a DataStore and optional middleware.

To initialize DataFlow, call the DataFlow.init method with your DataStore:

void main() {
  DataFlow.init(MyDataStore());
  runApp(MyApp());
}

DataFlow provides a stream of actions through the DataFlow.events property. You can listen to this stream to react to action events:

DataFlow.events.listen((action) {
  // Handle action events here
});

DataSync

DataSync is a widget that rebuilds its descendants based on the state of a DataStore. It listens to specific actions and updates the UI accordingly.

To use DataSync, wrap your widget tree with the DataSync widget and provide a builder function:

      DataSync<AppStore>(
          useDefaultWidgets: true,
          loadingBuilder: (context) {
            return const Center(child: CircularProgressIndicator());
          },
          errorBuilder: (context, error) {
            return Center(child: Text('An error occurred: $error'));
          },
          builder: (context, store, hasData) {
            return store.isLoggedIn ? TodoScreen() : LoginScreen();
          },
          actions: const {LoginAction},
        );

The builder function receives the current context, the DataStore, and the status of the actions. You can use this information to build your UI based on the state of the actions or you can use ::useDefaultWidgets:: property.

DataSyncNotifier

DataSyncNotifier is a widget that notifies listeners when specific DataActions occur. It is useful for performing side effects or triggering additional actions based on the status of an action.

To use DataSyncNotifier, wrap your widget tree with the DataSyncNotifier widget and provide a map of actions and their corresponding listeners:

DataSyncNotifier(
  actions: {
    FetchDataAction: (context, store, status) {
      // Handle the action status here
      if (status == DataActionStatus.success) {
        // Perform additional actions or side effects
      }
    },
  },
  child: MyChildWidget(),
),

The listeners will be called whenever the specified actions occur, allowing you to react to action status changes.

Middleware

Middleware allows you to intercept and modify actions before and after their execution. It provides a way to add custom logic, logging, or error handling to your actions.

To create a middleware, define a class that extends DataMiddleware and implement the preDataAction and postDataAction methods:

class LoggingMiddleware extends DataMiddleware {
  @override
  bool preDataAction(DataAction dataAction) {
    print('Starting action: ${dataAction.runtimeType}');
    return true;
  }

  @override
  void postDataAction(DataAction dataAction) {
    print('Finished action: ${dataAction.runtimeType} with status ${dataAction.status}');
  }
}

The preDataAction method is called before the action is executed, and the postDataAction method is called after the action is executed.

To add middleware to DataFlow, pass a list of middleware instances to the DataFlow.init method:

void main() {
  DataFlow.init(MyDataStore(), middlewares: [LoggingMiddleware()]);
  runApp(MyApp());
}

Error Handling

DataFlow provides built-in error handling for actions. If an exception occurs during the execution of an action, the action's status will be set to DataActionStatus.error, and the error will be available through the error property.

You can handle errors in your UI by checking the action status and displaying appropriate error messages:

DataSync<MyDataStore>(
  actions: {FetchDataAction},
  builder: (context, store, hasData) {
    if (context.dataSync().hasAnyActionError) {
         return const Center(child: Text('An error occurred'));
      }
    // Rest of your UI
  },
),

You can also handle errors in middleware by implementing custom error handling logic in the postDataAction method:

class ErrorHandlingMiddleware extends DataMiddleware {
  @override
  void postDataAction(DataAction dataAction) {
    if (dataAction.status == DataActionStatus.error) {
      // Handle the error here
      print('Error: ${dataAction.error}');
    }
  }
}

Best Practices

Here are some best practices to follow when using DataFlow:

• Keep your DataActions focused and single-purpose. Each action should represent a specific operation or task.
• Use meaningful names for your DataActions and DataStores to improve code readability.
• Leverage middleware for cross-cutting concerns like logging, error handling, or authentication.
• Use DataSync to rebuild your UI based on action status changes, and DataSyncNotifier for side effects and additional actions.
• Handle errors gracefully and provide meaningful error messages to the user.
• Avoid excessive nesting of actions using the next method. Keep the action flow simple and linear.

License

This project is licensed under the MIT License.

The above comparison table provides an overview of how DataFlow stacks up against other popular state management libraries for Flutter. For more detailed information and advanced usage, please refer to the official documentation.

Conclusion

DataFlow provides a powerful and flexible way to manage the state and data flow in your Flutter applications. By defining actions, using a centralized store, and leveraging widgets like DataSync and DataSyncNotifier, you can create reactive and responsive UIs with ease.

This documentation covers the core concepts and usage of DataFlow. For more advanced scenarios and detailed API reference, please refer to the official documentation.

Happy coding with DataFlow!