Data Layer Domain Layer

The Domain Layer. Let's revisit our architecture diagram Flutter App Architecture using data, domain, application, and presentation layers. As we can see, the models belong to the domain layer. They are retrieved by the repositories in the data layer below, and can be modified by the services in the application layer above.

However, something has to translate UI-specific values query strings, POST data, session, etc. into domain objects. This is where the application layer comes into play. It's job is to translate back and forth between the UI, the data layer and the domain, effectively hiding the domain from the rest of the system.

In this example, UserViewModel uses the GetUserUseCase to fetch user data and update the UI. 2. Domain Layer Defining Business Logic. The Domain Layer contains core business logic and application

The ViewModel calls the GetUserProfieUseCase and updates the UI layer through LiveData. Best Practices. Keep your business logic in use cases or interactors. Ensure your domain layer is UI-agnostic to promote reusability and testability. Data Layer. The data layer is responsible for managing all the data in your app. This includes fetching from

There is no Domain Service Layer in DDD. DDD has domain services that naturally belong to the domain layer.In some situations when the domain service needs to interact with other BCs or external systems, then the domain service interface is created in the domain layer, and the domain service implementation is created in the infrastructure layer. See the discussion around Listing 17-6 in

The domain layer is an optional layer that sits between the UI layer and the data layer. Figure 1. The domain layer's role in app architecture. The domain layer is responsible for encapsulating complex business logic, or simple business logic that is reused by multiple ViewModels. This layer is optional because not all apps will have these

Between the UI layer and the data layer is the domain layer, which is an optional layer. Complex business logic or simple business logic that is utilized by several ViewModels must be contained in the domain layer. Because not all apps will meet these requirements, this layer is optional. Use it only as necessary, such as to manage complexity

The data layer is dependant on the domain layer. The data layer fetches data and reads it into domain model objects, and then returns it up to the other layers. Domain layer is the most fundamental layer.

UI code is often tricky to test, so it's good to get as much logic as you can into a domain layer which is easily tested without having to do gymnastics to access the program through a UI 1. Data access is often slow and awkward, so using TestDoubles around the data layer often makes domain logic testing much easier and responsive.

The domain layer is responsible for encapsulating business logic, that is reused by the Presentation layer e.g. multiple ViewModels. This separation of concerns allows the domain layer to be used as a platform-independent module to reproduce business logic on different platforms e.g. Android, iOS, Web and be covered with unit testing.