In a previous article, we discussed Clean Architecture and SOLID Principles in detail, where we explored how to structure your code for better maintainability and scalability. If you’re unfamiliar with Clean Architecture and SOLID Principles, feel free to check out that article.

In this article, we’ll focus on how to apply Clean Architecture specifically in Flutter, using only Models, Repositories, Business Logic, and UI — without overwhelming yourself with too many layers.

Let’s dive straight into how you can apply these principles effectively in your Flutter app!

Layered Structure

Here’s a simplified structure for implementing Clean Architecture in Flutter:

Models: These represent the data structure of your app. For example, a User model may have fields like name, email, and id. Models are plain data objects, and they help your app interact with different data sources consistently.
Repositories: The repositories are responsible for fetching and storing data. They interact with external APIs, databases, or local storage to provide data to your business logic layer. By abstracting the data retrieval, repositories allow you to keep your app’s business logic clean and independent of data-fetching logic.
Business Logic (BLoC or Riverpod): This is where your business logic lives. Whether you’re using BLoC or Riverpod, this layer helps manage state and handle user inputs. It receives data from repositories, processes it, and updates the UI. By keeping the business logic separate, you make your app easier to maintain and test.
UI (Views & Widgets): This is your presentation layer. The UI listens to changes in the BLoC or Riverpod state and updates the view accordingly. It’s crucial to keep the UI simple, ensuring that it doesn’t contain any business logic.
This structure ensures that your code is clean, modular, and easy to maintain while still being scalable.

Tips for Better Code Quality

1. Create Small and Clean Widgets

A common mistake in Flutter development is creating large, complex widgets that handle multiple responsibilities. This makes your code harder to maintain and understand. Instead, break down your UI into small, reusable widgets, each responsible for one part of the UI.

2. Avoid Creating Widgets as Functions

Widgets should always be created using Stateless or Stateful classes instead of functions. This ensures that your widgets maintain their state efficiently and avoid being rebuilt unnecessarily. Widgets created with functions tend to rebuild more often than needed, leading to performance issues.

3. Organize Code Into Separate Files

Keep your codebase clean by organizing different functionalities into separate files. For example, keep UI widgets in their own files, repositories in their own folder, and BLoCs in another. This improves readability, makes navigation easier, and helps you find and fix issues faster.

4. Use Descriptive Naming Conventions

Clear, descriptive naming conventions make your code easier to understand and maintain. A good name should convey the purpose of the variable or function.

Examples of Good and Bad Naming:

Bad: doWork() — What work? Not clear.
Good: fetchUserData() — Clearly describes the task.
Bad: n — What is n? No context.
Good: userName — Easy to understand.
Bad: check() — What are we checking?
Good: validateEmail() — Clear about its task.

Conclusion

In this article, we explored how you can implement Clean Architecture in your Flutter apps without overcomplicating your code. By focusing on key layers like models, repositories, BLoC (or Riverpod), and UI, you can maintain a clean, modular structure that makes your app easier to scale and maintain. Following some best practices — such as creating small, reusable widgets, avoiding widget functions, organizing code into separate files, and using clear naming conventions — will significantly enhance the quality and readability of your code.