mvvm_provider 1.0.1

Simple and effective architecture MVVM using Provider to approach Flutter with lifecycles

example/lib/main.dart

import 'dart:convert';

import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import 'package:mvvm_provider/base/FlutterView.dart';
import 'package:mvvm_provider/base/FlutterViewModel.dart';
import 'package:shared_preferences/shared_preferences.dart';

void main() => runApp(ExampleApp());

class ExampleApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'MVVM Example',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: HomeView(),
    );
  }
}

class HomeView extends FlutterView {
  @override
  FlutterViewState<FlutterView, FlutterViewModel> getViewState() {
    return _HomeViewState();
  }
}

class _HomeViewState extends FlutterViewState<HomeView, HomeViewModel> {
  @override
  void onViewModelReady() {
    debugPrint('-------------_HomeViewState onCreate');
    viewModel.getTodoList();
  }

  @override
  void onResume() {
    super.onResume();
    debugPrint('-------------_HomeViewState onResume');
  }

  @override
  void onPause() {
    super.onPause();
    debugPrint('-------------_HomeViewState onPause');
  }

  @override
  Widget getView() {
    return Scaffold(
      backgroundColor: Colors.grey[300],
      appBar: AppBar(
        title: Text('MVVM Example'),
      ),
      body: SafeArea(
        child: Column(
          children: <Widget>[
            Expanded(
                child: viewModel.isLoading
                    ? Center(child: CupertinoActivityIndicator())
                    : viewModel.list.isEmpty
                        ? Center(child: Text('No data'))
                        : ListView.separated(
                            padding: EdgeInsets.all(16),
                            itemBuilder: (_, index) =>
                                _todoItem(viewModel.list[index]),
                            separatorBuilder: (_, __) => SizedBox(height: 16),
                            itemCount: viewModel.list.length)),
            Container(
              color: Colors.grey,
              width: double.infinity,
              height: kToolbarHeight,
              child: Center(
                child: FlatButton(
                    onPressed: () {
                      viewModel.addTodo(Todo(
                          DateTime.now().millisecondsSinceEpoch,
                          'Hi ${DateTime.now().millisecondsSinceEpoch}'));
                    },
                    child: Text('Add Todo')),
              ),
            )
          ],
        ),
      ),
    );
  }

  @override
  HomeViewModel getViewModel() {
    return HomeViewModel();
  }

  Widget _todoItem(Todo item) {
    return Container(
      padding: EdgeInsets.all(16),
      color: Colors.white,
      child: Row(
        children: <Widget>[
          Expanded(child: Text(item.todo)),
          SizedBox(width: 8),
          FlatButton(
              onPressed: () {
                viewModel.deleteTodo(item);
              },
              child: Text('Delete'))
        ],
      ),
    );
  }
}

class HomeViewModel extends FlutterViewModel {
  List<Todo> list = [];

  void getTodoList() async {
    final data = await _getTodos();
    list.clear();
    list.addAll(data);
    isLoading = false;
    notifyListeners();
  }

  void addTodo(Todo todo) async {
    final data = await _getTodos();
    data.add(todo);
    await _setTodos(data);
    getTodoList();
  }

  void deleteTodo(Todo todo) async {
    final data = await _getTodos();
    data.removeWhere((element) => element.id == todo.id);
    await _setTodos(data);
    getTodoList();
  }

  Future<List<Todo>> _getTodos() async {
    final sp = await SharedPreferences.getInstance();
    if (!sp.containsKey('todos') || sp.getString('todos') == null) return [];
    final rawJson = sp.getString('todos');
    final parsedJsonList = jsonDecode(rawJson) as List<dynamic>;
    return parsedJsonList.map((json) => Todo.fromJson(json)).toList();
  }

  Future<List<Todo>> _setTodos(List<Todo> data) async {
    final sp = await SharedPreferences.getInstance();
    if (data == null || data.isEmpty) {
      await sp.setString('todos', null);
      return data;
    }
    final parsedJsonList = data.map((single) => single.toJson()).toList();
    await sp.setString('todos', jsonEncode(parsedJsonList));
    return data;
  }
}

class Todo {
  int id;
  String todo;

  Todo(this.id, this.todo);

  Todo.fromJson(Map<String, dynamic> json)
      : id = json['id'],
        todo = json['todo'];

  Map<String, dynamic> toJson() => {'id': id, 'todo': todo};
}