A simple Flutter Registration Form Application to demonstrate the usage for MVVM design pattern using ChangeNotifiers, RxDart, Providers (Dependency Injection),Retrofit-Dio along with Test Cases & isolation of UI, business logic and data sources.

The application demonstrates the best practices which can be adopted in flutter application development to avoid code maintaince issues overtime.

• MVVM Architecture - Robust, testable, and maintainable app with classes for managing your UI component lifecycle and handling data persistence.
• Isolating of UI, business logic and data sources responsibilities creating a Testable system
• Provider - A pragmatic lightweight dependency injection framework [MultiProvider] for flutter which also is helpful in State Management.
• ChangeNotifier - a simple class included in the Flutter SDK which provides change notification to its listeners
• RxDart - Build data objects that notify views when the underlying data changes.
• Mockito - An Flutter testing framework for unit and runtime UI tests.
• Internationalizing - Flutter provides widgets and classes that help with internationalization and the Flutter libraries themselves are internationalized.
• Retrofit-Dio - Retrofit.dart is an dio client generator using source_gen and inspired by Chopper and Retrofit.

Let’s start explaining Data Flow in Clean Architecture as follows,

1. UI calls method from ViewModel.
2. ViewModel executes Use case.
3. Use case combines data from Multiple Repositories.
4. Each Repository returns data from a Data Source (Cached or Remote). [ In current scope only Remote ]
5. Information flows back to the UI where we display the list of requested information.

In the Architecture adopted, relationship that exists between the different layers is very crucial.

Different layers & their boundaries are explained below,

Presentation/App Layer contains UI (Views)_ that are coordinated by ViewModels which execute one or more Use cases._ Presentation layer depends on Domain Layer.

Domain Layer It contains Entities, Use cases & Repository Interfaces. Use cases combine data from one or more Repository Interfaces.

Data Layer contains Repository Implementations and one or more Data Sources. Repositories are responsible to coordinate data from the different Data Sources. Data Layer depends on Domain Layer.

The Architecture helps Isolates UI, business logic and data sources' responsibilities creating a Testable system.

Other components include,

Providers which are used for state management adopting Producer & Consumer design patterns.

ProxyProviders are useful to create dependent providers helping to achieve constructor dependency injection.

Mockito used to mock dependencies which are useful to during test cases.

If you've found an error in this sample, please file an issue: https://github.com/faiyyazs/flutter_registration_form/issues

Patches are encouraged, and may be submitted by forking this project and submitting a pull request through GitHub.