Day 89 of 100daysofcode : Understanding Clean Architecture in Flutter🧹

Ever heard of Clean Architecture but unsure how it applies to Flutter? Let’s demystify it!

What is Clean Architecture?

It’s a design pattern that organizes code into layers to separate concerns, making apps more scalable, testable, and maintainable. The core idea: dependencies flow inward, and inner layers don’t depend on outer layers.

The 3 Key Layers

  1. Presentation Layer (UI)
    What: Widgets, state management (e.g., Cubit, Provider), and UI logic.
    Why: Handles how data is displayed.
    Rule: Never contains business logic!
  2. Domain Layer (Core Business Logic)
    What: Entities (business models), use cases (app features), and repository interfaces.
    Why: Defines what the app does, independent of frameworks or data sources.
    Rule: Pure Dart—no Flutter dependencies!
  3. Data Layer (Data Sources)
    What: Repositories (implementation), APIs, databases, local storage.
    Why: Fetches/stores data (e.g., REST API ↔ Domain).
    Rule: Implements interfaces defined in the Domain layer.

How It Fits in Flutter

  • Independence: Change your UI (Presentation) or switch databases (Data) without breaking business logic (Domain).
  • Testability: Test Domain layer without Flutter dependencies; mock Data layer for UI tests.
  • Scalability: Add features or refactor code with minimal ripple effects.

Why You’ll Love It

Future-proof: Adapt to new libraries/frameworks easily.
Test-friendly: Isolate layers for unit/integration tests.
Team-ready: Clear separation simplifies collaboration.

Quick Tips for Flutter

Use dependency injection (e.g., get_it, riverpod) to connect layers.
Keep the Domain layer pure (no BuildContext or widgets).
Start small! Even splitting UI and logic is a win.

Clean Architecture isn’t about perfection—it’s about intentional structure.
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