djinn_flutter

Djinn-state implementation for flutter.

The djinn-state is an application state management, using class inheritance to create services.

The services are classes with business logic, side-effects and state.

Getting Started

main.dart

void main() {
  Djinn().register(() => Counter()); // singleton => same instance on every 'get' call
  // or
  Djinn().register(() => Counter(), true); // scoped = true => new instance on every 'get' call
  Djinn().init();

  runApp(MyApp());
}

counter.dart

class Counter extends DjinnService {
  var state = {
    'count': 0
  };

  increment() {
    patch({
      'count': state['count'] + 1
    });
  }

  decrement() {
    patch({
      'count': state['count'] - 1
    });
  }
}

counter_widget.dart

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

  final String title;

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

class _CounterState extends State<Counter> {
  final Counter counter = Djinn().get(); // <= Look this

  @override
  void initState() {
    super.initState();
    counter.listen(this); // <= Look this
  }

  @override
  void dispose() {
    counter.dispose(this); // <= Look this
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    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.state['count']}', // <= Look this
              style: Theme.of(context).textTheme.display1,
            ),
          ],
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: counter.increment, // <= Look this
        tooltip: 'Increment',
        child: Icon(Icons.add),
      ),
    );
  }
}

Listening to changes

You can use the default way listen and dispose.

Or if you want more control:

var unsubscribe = counter.subscribe((Map<String, StateUpdate> update) {
});

StateUpdate is a data class that contains the current and previous values.

The update is a Map that contains all property updates with its corresponding values.

The unsubscribe is a function that when called will remove the given subscribe function of the listeners list.

Important

The init function is important, and must be called after all services was registered.

That function is responsible to create instances of the singleton services (scoped = false) and call it's init methods.

Communication between services

Just call the container.get() function inside the init function.

class ServiceA extends DjinnService {
  void printOk() {
    print('ok');
  }
}

class ServiceB extends DjinnService {
  ServiceA service;
  init() {
    service = Djinn().get();
  }
  
  doSomething() {
    service.printOk();
  }
}

Libraries

djinn_flutter