Flutter Architecture Patterns: BLoC, Provider, Riverpod, etc.

Flutter’s architecture patterns are something you have to get right. Get them wrong, and your app won’t scale, will be hard to maintain, and end up an utter headache. There are three Flutter state management and data flow architectures that excel: BLoC (Business Logic Component), Provider, and Riverpod.

In this article, we’ll talk about the basics of BLoC – Business Logic Components – first. Then, compare Provider and Riverpod so you can see how different they are and why their customizability transforms Flutter into an efficient ecosystem.

BLoC Architecture

BLoCs separate business logic from UI components. This allows for sharing code, conducting tests, and separating concerns. The unidirectional reactive data flow pattern is based on streams and sinks. It’s most powerful in complex apps with many widgets sharing state or when handling user interactions over time.

BLoCs sit between the UI layer and the data layer (repositories or databases). They take user interactions from the UI to apply business logic and then update the UI through streams. This modular development allows developers to scale their apps without affecting one layer when changes are made to another.

All this makes it easier for developers to work with predictable code that’s a breeze to test. When business logic is separated from UI components, you can effortlessly unit-test different parts of your application. This keeps the codebases clean and helps with team collaboration.

Provider vs. Riverpod

Remi Rousselet’s Provider package has always been a strong contender for simpler state management in Flutter because it wraps around InheritedWidget for reuse across an app. Widgets listen for changes through Provider instead of having access to all stateful widgets in an app listening through Provider directly. By only rebuilding what’s necessary within them, resources are used efficiently resulting in high-performance apps overall. However, scalability with large projects becomes difficult as well as testing with complex scenarios.

Riverpod was built as a direct answer to these limitations in Provider while still being fully compatible with the Flutter framework. Unlike Provider, Riverpod doesn’t use widgets and, therefore, doesn’t need context. You won’t find much boilerplate code or common pitfalls in Riverpod that you do in Provider. For example, there is no inability to access the state from an app’s initialization code.

Riverpod also greatly improves testability and scalability. With state management untangled from the widget tree, a more predictable state management pattern can be achieved. This new architecture supports complex scenarios. These scenarios include modifying the state from outside of the widget tree and accessing it in a type-safe way. Also, thanks to its ability to provide scoped overrides, developers can replace implementations during tests which encourages high-quality code.

To sum up, deciding between BLoC, Provider, and Riverpod mostly depends on a Flutter project’s specific requirements. BLoC is great for complex apps that need serious business logic handling. On the other hand, Provider is simpler and still effective for light state management needs. But Riverpod takes Provider’s offering to the next level by addressing its limitations and providing an enhanced flexible solution.

Ultimately, understanding these patterns is essential for Flutter devs wanting to create efficient apps that are scalable and maintainable. Each pattern offers different app performance capabilities & user experiences. Also, check out our article on Redux architecture in Flutter.