RX MVVM

This package helps create MVVM applications using RX programming as communication tools between UI and ViewModel layer.

This package uses RxCommands, you can check it's documentation for more information.

This package depends on Injectable/Injectable Generator/Get It as dependency injector container. You need to configure them as well.

Instalation

dependencies:
  rx_mvvm:
  injectable:
  get_it:

dev_dependencies:
  rx_mvvm_builder:
  injectable_generator:
  build_runner:

Setup

import 'package:rx_mvvm/rx_mvvm.dart';

void main() {
  // Injectable/Get It configuration
  configureDependencies();
  Injector.init(getIt);

  runApp(MyApp());
}

ViewModel

To setup a ViewModel you need to extend from _ViewModelBase and override default constructors.

import 'package:injectable/injectable.dart';
import 'package:rx_mvvm/rx_mvvm.dart';

// Define the part file
part 'counter_view_model.g.dart';

@singleton
class Service {}

@ViewModel()
class CounterViewModel extends _ViewModelBase {
  int counter = 0;

  @Input()
  late int title;

  @Output()
  final EventEmitter<String> output = EventEmitter();

  // Make default constructor private
  CounterViewModel._();
  // Override contructor with the generate one (Is the class name without ViewModel)
  factory CounterViewModel(Service service) = _Counter;

  // Life Cycles
  @override
  void OnInit() {}
  @override
  void onUpdate() {}
  @override
  Future<void> onDispose() async {
    // must call super
    super.onDispose();
  }

  // Commands must be private
  @Command()
  int _add() {
    counter += 1;
    return counter;
  }
}

@Input({ String? property }) - Bind view property, if no property is passed defaults to variable name. @Output({ String? property }) - Bind view callbacks, if no property is passed defaults to variable name. @Command(...rx_command options) - Create a command action, will be the public version of the method.

View

import 'package:example/counter_view_model.dart';
import 'package:flutter/material.dart';
import 'package:rx_mvvm/rx_mvvm.dart';

class CounterView extends RxView<CounterViewModel> {
  // Binds to viewModel
  final String title;
  final String Function() output;

  CounterView({Key? key, required this.title, required this.output}) : super(key: key);

  // Life Cycles
  @override
  void onFocusLost() {}
  @override
  void onFocusGained() {}
  @override
  void onVisibilityLost() {}
  @override
  void onVisibilityGained() {}
  @override
  void onForegroundLost() {}
  @override
  void onForegroundGained() {}
  @override
  void didChangeDependencies() {}
  @override
  void afterFirstLayout(BuildContext context) {}

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        backgroundColor: Theme.of(context).colorScheme.inversePrimary,
        title: Text(title),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            const Text(
              'You have pushed the button this many times:',
            ),
            StreamBuilder(
              // viewModel property is available
              stream: viewModel.onAdd.values,
              initialData: viewModel.counter,
              builder: (context, snapshot) {
                return Text(
                  '${snapshot.data}',
                  style: Theme.of(context).textTheme.headlineMedium,
                );
              },
            ),
          ],
        ),
      ),
      floatingActionButton: FloatingActionButton(
        // viewModel actions
        onPressed: viewModel.add,
        tooltip: 'Increment',
        child: const Icon(Icons.add),
      ),
    );
  }
}

• this.viewModel - Is available in all classe and all life cycle methods.
• this.viewModel.{commandName} - each command have a public version to be called.
• this.viewModel.on{commandName} - each command has a property with all events
  • values - Stream of returned values
  • results - Stream of CommandsResults
  • exceptions - Stream of errors
  • executing - Stream of command current state
  • canExecute - Stream of command availability
  • command - Command object