Using the Model-View-Controller (MVC) pattern in Flutter

Introduction

Flutter is a popular cross-platform mobile application development framework that allows developers to build beautiful and high-performance mobile applications. Flutter follows a reactive programming model, where widgets update themselves when their state changes. To build complex applications, it’s important to follow a pattern that helps to separate concerns and maintain code structure. One such pattern is the Model-View-Controller (MVC) pattern.

MVC pattern

MVC pattern is a software design pattern that separates an application into three main components: Model, View, and Controller. The Model represents the data and the business logic, the View represents the user interface, and the Controller acts as an intermediary between the Model and View, controlling the flow of data and updating the View based on changes in the Model.

In this article, we’ll explore how to use the MVC pattern in Flutter.

Step 1: Creating the Model :

The Model represents the data and business logic of our application. In Flutter, we can create a Model class that contains the data we want to represent. For example, let’s create a simple User model:

class User {
  String name;
  int age;
  
  User({required this.name, required this.age});
}

Step 2: Creating the View:

The View represents the user interface of our application. In Flutter, we can create a View using Widgets. For example, let’s create a simple User Profile View:

class UserProfileView extends StatelessWidget {
  final User user;
  
  const UserProfileView({required this.user});
  
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('User Profile'),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            Text('Name: ${user.name}'),
            Text('Age: ${user.age}'),
          ],
        ),
      ),
    );
  }
}

Step 3: Creating the Controller:

The Controller acts as an intermediary between the Model and View. In Flutter, we can create a Controller by creating a StatefulWidget that contains the Model and View. For example, let’s create a simple User Profile Controller:

class UserProfileController extends StatefulWidget {
  final User user;
  
  const UserProfileController({required this.user});
  
  @override
  _UserProfileControllerState createState() => _UserProfileControllerState();
}

class _UserProfileControllerState extends State<UserProfileController> {
  late User _user;
  
  @override
  void initState() {
    super.initState();
    _user = widget.user;
  }
  
  @override
  Widget build(BuildContext context) {
    return UserProfileView(user: _user);
  }
}

In the above code, we created a StatefulWidget called UserProfileController that takes a User object as input. In the _UserProfileControllerState class, we initialized a local _user variable with the user object passed from the widget. In the build method, we returned a UserProfileView widget with the _user variable passed as an argument.

Step 4: Using the Controller in the App:

To use the Controller in our app, we can create a MaterialApp widget and use the UserProfileController as the home screen. For example:

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  final User user = User(name: 'John', age: 30);
  
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'MVC in Flutter',
      home: UserProfileController(user: user),
    );
  }
}

In the above code, we created a MyApp widget that initializes a User object with a name and age. In the build method, we returned a MaterialApp widget with a title and the UserProfileController as the home screen.

Conclusion

In this article, we explored how to use the Model-View-Controller (MVC) pattern in Flutter. We created a simple User Model, a UserProfileView, and a UserProfileController that acted as an intermediary between the Model and View. Finally, we used the Controller in our app by creating a MaterialApp widget and using the UserProfileController as the home screen.

By using the MVC pattern, we were able to separate concerns and maintain code structure, which makes it easier to develop, test, and maintain our application.