How did you facilitate interaction and data transformation between different levels and layers of the architectural scheme?

In Android applications, interaction and data transformation between layers (for example, between the data layer, business logic, and UI) are usually implemented through architecture patterns such as MVVM or MVP.

To transfer data between layers, DTOs (Data Transfer Objects) or models adapted for a specific layer are often used. For example, the data layer returns entities, which are transformed into business logic models, and then into view models for the UI.

Example: an object UserEntity from the repository layer is transformed into UserDomainModel, and then into UserViewModel for display.

// Example of transforming Entity into ViewModel
fun UserEntity.toViewModel(): UserViewModel {
    return UserViewModel(
        id = this.id,
        displayName = "${this.firstName} ${this.lastName}",
        email = this.email
    )
}

This approach ensures separation of concerns and simplifies testing and maintenance of the code.