Clean Architecture layers in Flutter

Introduction

Clean Architecture helps organize your app into clear parts. This makes your app easier to build, test, and change later.

When building an app that will grow bigger over time.

When you want to keep your app easy to fix and add new features.

When working with a team to keep code clear and organized.

When you want to separate app logic from user interface.

When you want to write tests for your app easily.

Syntax

Flutter

Presentation Layer
Domain Layer
Data Layer

Presentation Layer: Shows UI and handles user actions.

Domain Layer: Contains app rules and logic, independent of UI or data.

Data Layer: Manages data sources like APIs or databases.

Examples

This shows what each layer usually contains in a Flutter app.

Flutter

Presentation Layer: Flutter widgets, UI code
Domain Layer: Use cases, business rules
Data Layer: API calls, database access

Shows the flow of calls between layers.

Flutter

Presentation Layer -> calls -> Domain Layer -> calls -> Data Layer

Sample App

This Flutter app shows a simple example of Clean Architecture layers. The domain layer has a use case that returns a greeting. The presentation layer shows this greeting in the UI.

Flutter

import 'package:flutter/material.dart';

// Domain Layer: simple use case
class GetGreeting {
  String call() => 'Hello from Domain Layer!';
}

// Presentation Layer: UI widget
class MyApp extends StatelessWidget {
  final GetGreeting getGreeting = GetGreeting();

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(title: Text('Clean Architecture Example')),
        body: Center(
          child: Text(getGreeting()),
        ),
      ),
    );
  }
}

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

Important Notes

Keep domain layer free from Flutter or platform code to make it reusable.

Presentation layer depends on domain layer, but domain layer does not depend on presentation.

Data layer handles where data comes from, like web or local storage.

Summary

Clean Architecture divides app into Presentation, Domain, and Data layers.

This separation makes apps easier to maintain and test.

Presentation handles UI, Domain handles logic, Data handles data sources.