bsev 0.7.2

Useful to aid in the use of BloC pattern with dependency injection

BSEV (BloC,Streams,Events,View)

Set of packages and utilitarian functions that help in the use of BloC pattern with dependency injection.

With bsev you will use the Bloc pattern in a simple, reactive and organized way. Communication between the business logic and the view occurs entirely through two-way streams.

Usage

To use this plugin, add bsev as a dependency in your pubspec.yaml file.

We should initially create the class that represents our Streams and Events:

Streams

import 'package:bsev/bsev.dart';

class HomeStreams extends StreamsBase{

  var count = BehaviorSubjectCreate<Int>(initValue: 0);
  //var count = StreamCreate<Int>();
  //var count = PublishSubjectCreate<Int>();
  //var count = ReplaySubjectCreate<Int>();

  @override
  void dispose() {
    count.close();
  }

}

Events

import 'package:bsev/bsev.dart';

class HomeEvents extends EventsBase{}

class IncrementEvent extends HomeEvents{}

Now we can create our Bloc, class that will be centralized the business rule.

Bloc

import 'package:bsev/bsev.dart';

class HomeBloc extends BlocBase<HomeStreams,HomeEvents>{

  //If you need to communicate with some instantiated BloC, regardless of whether part of your tree of widgets can use:
  //dispatchToBloc<OtherBloc>(MsgEvent());
  
  //If you need to send an event to the view:
  //dispatchView(MyEvent());

  @override
  void initView() {
  }
  
  @override
  void eventReceiver(EventsBase event) {
  
  // called when the Bloc receives an event
  
    if(event is IncrementEvent){
      streams.count.set(streams.count.value + 1)
    }
    
  }
}

Note: If you do not want to use events (for a screen that only starts, loads and displays data) you can use EventsBase as an event. Ex: BlocBase <HomeStreams, EventsBase>

In our bloc we have 2 mandatory methods: initState and eventReceiver:

initView: In the first buildView this method is invoked;

eventReceiver: Invoked whenever the pad receives an event;

View

import 'package:bsev/bsev.dart';

class HomeView extends BlocStatelessView<HomeBloc,HomeStreams> {

  @override
  void eventReceiver(HomeEvents event) {
    // performs action received by the bloc
  }
  
  @override
  Widget buildView(BuildContext context, HomeStreams streams) {

    return Scaffold(
      appBar: AppBar(),
      body: _buildBody(streams),
      floatingActionButton: FloatingActionButton(
          onPressed: (){
            dispatch(IncrementEvent());
          }
      ),
    );
    
  }
    
  Widget _buildBody(HomeStreams streams) {

    return StreamBuilder(
      stream: streams.count.get,
      initialData: 0,
      builder: (_,snapshot){

        int count = 0;
        if(snapshot.hasData){
          count = snapshot.data;
        }

        return Center(
          child: Text(count)
        )
      }
    );

  }
  
}

As our Bloc and our StreamsBase will be injected automatically, we should configure it in the Injector in the main of our application:

  MyApp(){

    var injector = Injector.appInstance;
    injector.registerDependency((i)=> HomeBloc());
    injector.registerDependency((i)=> HomeStreams());
    
  }

Questions about how to use the injector consult documentation.

Finally we instantiate our HomeView running:

HomeView().create()

More complex example is found here: exemplo

Using Stateful Widget

To stateful widget is necessary use mixin and add "create":

class HomeView extends StatefulWidget {

  Widget create(){
    return BlocProvider<BlocBase,StreamsBase>(
      child: this,
    );
  }
  
  @override
  _HomeViewState createState() => _HomeViewState();
}

class _HomeViewState extends State<HomeView> with BlocViewMixin<HomeBloc,HomeStreams>{

  @override
  void eventReceiver(HomeEvents event) {
    // performs action received by the bloc
  }
  
  @override
  Widget buildView(BuildContext context, HomeStreams streams) {
    return Scaffold(
      appBar: AppBar(),
      body: _buildBody(streams),
      floatingActionButton: FloatingActionButton(
          onPressed: (){
            dispatch(IncrementEvent());
          }
      ),
    );
  }
  
  Widget _buildBody(HomeStreams streams) {
    
      return StreamBuilder(
        stream: streams.count.get,
        initialData: 0,
        builder: (_,snapshot){
          
          int count = 0;
          if(snapshot.hasData){
            count = snapshot.data;
          }
          
          return Center(
            child: Text(count)
          )
        }
      );
      
  }
  
}

Used packages

Packages	pub
rxdart
injector
provider

User cases

Apps
FlutterNews
DartLangBr