MVC Application #

A Flutter Framework using the MVC Design Pattern #

mvc_application Allows for easier and, dare I say, faster development and better maintenability. No 're-inventing of the wheel' with already built-in capabilities and features. Accommodating and Integrated features:

Error Handling
System Preferences
App Notifications
Date picker
App Color picker
Dialog Box
Customizable Bottom Bar
Loading Screen
Time Zones

Installing I don't always like the version number suggested in the 'Installing' page. Instead, always go up to the 'minor' semantic version number when installing this library package. This means always trailing with one zero, '.0'. This allows you to take in any 'minor' versions introducing new features as well as any 'patch' versions that involves bugfixes. Semantic version numbers are always in this format: major.minor.patch. I know I should be changing the 'major' instead, but since I chose to release this to production with a lot of changes to come, I don't want to be up to version '27.0.0' before I know it!

patch - I've made bugfixes
minor - I've introduced new features
major - I've essentially made a new app. It's broken backwards-compatibility and has a completely new user experience. You won't get this version until you increment the major number in the pubspec.yaml file.

And so, in this case, add this to your package's pubspec.yaml file instead:

dependencies:
   mvc_application:^7.0.0-nullsafety

Note, in fact, this package serves as a 'wrapper' to the core MVC package:

MVC Pattern #

Usage #

Like many other design patterns and architectures, MVC separates three common 'areas of concern' found in computer programs. Specifically, there's the separation of the program's logic from its inteface and from its data. The many design patterns that have come into vogue since MVC's inception in the early 1970's are, in fact, decendants of MVC.

Note, computer platforms themselves have come full circle in the last 40 years. From mainframes to desktop computers in the first twenty years, and then website applications to mobile apps in the last twenty years. A computer now fits in the palm of your hand, and because of this, MVC again fits as the software architecture for the apps it runs. mvcTypes

Implementing the MVC framework using two common example apps:

The Counter App

import 'package:flutter/material.dart';

import 'package:mvc_application/view.dart'
    show AppStatefulWidget, AppState, StateMVC;

import 'package:mvc_application/controller.dart' show ControllerMVC;

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

class MyApp extends AppStatefulWidget {
  MyApp({Key? key}) : super(key: key);
  // Allow for hot reloads.
  @override
  AppState createView() => View();
}

class View extends AppState {
  factory View() => _this ??= View._();
  View._()
      : super(
    title: 'Flutter Demo',
    home: const MyHomePage(),
    debugShowCheckedModeBanner: false,
    theme: ThemeData(
      primarySwatch: Colors.blue,
    ),
  );
  static View? _this;
}

class MyHomePage extends StatefulWidget {
  const MyHomePage({Key? key, this.title = 'Flutter Demo Home Page'})
      : super(key: key);
  // Fields in a StatefulWidget should always be "final".
  final String title;
  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends StateMVC<MyHomePage> {
  _MyHomePageState() : super(Controller()) {
    // Acquire a reference to the particular Controller.
    // ignore: avoid_as
    con = controller as Controller;
  }
  late Controller con;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            Text(
              widget.title,
            ),
            Text(
              '${con.counter}',
              style: Theme.of(context).textTheme.headline4,
            ),
          ],
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: () {
          setState(con.incrementCounter);
        },
        tooltip: 'Increment',
        child: const Icon(Icons.add),
      ),
    );
  }
}

class Controller extends ControllerMVC {
  factory Controller() => _this ??= Controller._();
  Controller._();
  static Controller? _this;

  int get counter => _Model.counter;
  // The Controller knows how to 'talk to' the Model.
  void incrementCounter() => _Model._incrementCounter();
}

// ignore: avoid_classes_with_only_static_members
/// Not good form to use a 'static class.'
class _Model {
  static int get counter => _counter;
  static int _counter = 0;
  static int _incrementCounter() => ++_counter;
}

Name Generator App

import 'package:english_words/english_words.dart' show generateWordPairs;

import 'package:flutter/material.dart';

import 'package:mvc_application/view.dart'
    show AppStatefulWidget, AppState, Colors, StateMVC;

import 'package:mvc_application/controller.dart' show ControllerMVC;

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

class NameApp extends AppStatefulWidget {
  // Allows for hot reloads.
  @override
  AppState createView() => MyApp();
}

class MyApp extends AppState {
  factory MyApp() => _this ??= MyApp._();
  MyApp._()
      : super(
          title: 'Startup Name Generator',
          home: RandomWords(),
          theme: ThemeData(
            primaryColor: Colors.white,
          ),
          debugShowCheckedModeBanner: false,
        );
  static MyApp? _this;
}

class RandomWords extends StatefulWidget {
  @override
  State createState() => _RandomWordsState();
}

class _RandomWordsState extends StateMVC<RandomWords> {
  _RandomWordsState() : super(Con()) {
    con = controller as Con;
  }
  late Con con;

  final TextStyle _biggerFont = const TextStyle(fontSize: 18.0);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Startup Name Generator'),
        actions: <Widget>[
          IconButton(
              icon: const Icon(Icons.list),
              onPressed: () {
                pushSaved(context);
              }),
        ],
      ),
      body: _buildSuggestions(),
    );
  }

  Widget _buildSuggestions() {
    return ListView.builder(
      padding: const EdgeInsets.all(16.0),
      itemBuilder: (context, i) {
        // Add a one-pixel-high divider widget before each row in theListView.
        if (i.isOdd) return Divider();
        final index = i ~/ 2;
        // If you've reached the end of the available word pairings...
        if (index >= con.length) {
          // ...then generate 10 more and add them to the suggestions list.
          con.addAll(10);
        }
        return buildRow(index);
      },
    );
  }

  void pushSaved(BuildContext context) {
    Navigator.of(context).push(
      MaterialPageRoute<void>(
        builder: (BuildContext context) {
          final Iterable<ListTile> tiles = this.tiles;

          List<Widget> divided;

          if (tiles.isEmpty) {
            divided = [];
          } else {
            divided = ListTile.divideTiles(
              context: context,
              tiles: tiles,
            ).toList();
          }

          return Scaffold(
            appBar: AppBar(
              title: const Text('Saved Suggestions'),
            ),
            body: ListView(children: divided),
          );
        },
      ),
    );
  }

  Widget buildRow(int? index) {
    if (index == null || index < 0) index = 0;

    String something = con.something(index);

    final alreadySaved = con.contains(something);

    return ListTile(
      title: Text(
        something,
        style: _biggerFont,
      ),
      trailing: Icon(
        alreadySaved ? Icons.favorite : Icons.favorite_border,
        color: alreadySaved ? Colors.red : null,
      ),
      onTap: () {
        setState(() {
          con.somethingHappens(something);
        });
      },
    );
  }

  Iterable<ListTile> get tiles => con.mapHappens(
        (String something) {
          return ListTile(
            title: Text(
              something,
              style: _biggerFont,
            ),
          );
        },
      );
}

class Con extends ControllerMVC {
  // Supply only one instance of this Controller class.
  factory Con() => _this ??= Con._();

  static Con? _this;

  Con._() {
    model = _Model();
  }

  late _Model model;

  int get length => model.length;

  void addAll(int count) => model.addAll(count);

  String something(int index) => model.wordPair(index);

  bool contains(String something) => model.contains(something);

  void somethingHappens(String something) => model.save(something);

  Iterable<ListTile> mapHappens<ListTile>(ListTile Function(String v) f) =>
      model.saved(f);
}

class _Model {
  final List<String> _suggestions = [];

  int get length => _suggestions.length;

  String wordPair(int? index) {
    if (index == null || index < 0) index = 0;
    return _suggestions[index];
  }

  bool contains(String? pair) {
    if (pair == null || pair.isEmpty) return false;
    return _saved.contains(pair);
  }

  final Set<String> _saved = Set();

  void save(String? pair) {
    if (pair == null || pair.isEmpty) return;
    final alreadySaved = contains(pair);
    if (alreadySaved) {
      _saved.remove(pair);
    } else {
      _saved.add(pair);
    }
  }

  Iterable<ListTile> saved<ListTile>(ListTile Function(String v) f) =>
      _saved.map(f);

  Iterable<String> wordPairs([int count = 10]) => _makeWordPairs(count);

  void addAll(int count) => _suggestions.addAll(wordPairs(count));
}

Iterable<String> _makeWordPairs(int count) =>
    generateWordPairs().take(count).map((pair) => pair.asPascalCase);