Overview

Recently I started off working for Unicred Mobile Banking as a Senior Android Engineer.

The app had a huge monolithic and legacy codebase written in Java. So, my first task at Unicred was to define a strategy of modularization and refactoring on the app.

We had to separate the app, initially, into three layers which are: the domain, data, and presentation.

Since the code was very tightly coupled, I decided, at first, to place all application entities within the domain layer.

However, we know how many boilerplate we need to write to create a new feature-module, don't we? ViewModel, Activity or Fragment, UseCases, Many interfaces, Datasources and Repositories and so on. So in order to turn this process easier, I built this "architecture-code-generator" to create all of the templates we need on the project for each new feature.

Download Generator

implementation 'com.mctech.architecture:generator:2.0.0'

Related Library

Mvvm Architecture Toolkit - It is a personal MVVM architecture library that contains the base codebase generated here.

Sample

Here is a Real Android App implementing this library to define its architecture.

Creating an empty feature

To start your generator you will need a ProjectSettings instance and a FeatureSettings instance. Here is an example:

fun main() {
    val projectSettings = ProjectSettings(
        basePackageName = Package("com.mctech.architecture")
    )

    val featureSettings = FeatureSettings(
        createDependencyInjectionModules = false,
        createBothRemoteAndLocalDataSources = true,
        presentationViewModel   = PresentationMode.ActivityAndFragment,
        projectSettings         = projectSettings,
        fileDuplicatedStrategy  = FileDuplicatedStrategy.Replace
    )

    // Here is an empty feature generated
    FeatureGenerator(
        settings    = featureSettings,
        featureName = "FeatureEmpty"
    ).newFeature {}
}

All you are going to do is run this main function and the files are going to be generated.

Generated files

Domain Layer

• FeatureEmpty.kt
• FeatureEmptyService.kt

Data Layer

• FeatureEmptyDataSource.kt
• LocalFeatureEmptyDataSource.kt
• RemoteFeatureEmptyDataSource.kt - Check out createBothRemoteAndLocalDataSources on FeatureSettings
• FeatureEmptyRepository.kt
• FeatureEmptyAPI.kt - Check out createBothRemoteAndLocalDataSources on FeatureSettings

Presentation Layer (New Module)

• settings.gradle - Add new module on the current project file.
• build.gradle
• AndroidManifest.xml
• strings.xml
• activity_feature_empty.xml - Check out PresentationMode on FeatureSettings
• fragment_feature_empty.xml - Check out PresentationMode on FeatureSettings
• FeatureEmptyActivity.kt- Check out PresentationMode on FeatureSettings
• FeatureEmptyFragment.kt - Check out PresentationMode on FeatureSettings
• FeatureEmptyViewModel.kt

Creating a complete feature with business and presentation logic

To start your generator you will need a ProjectSettings instance and a FeatureSettings instance. Here is an example:

fun main() {

    ...
    
    FeatureGenerator.newFeature(
        settings    = featureSettings,
        featureName = "ComplexFeature"
    ) {

        // Add fields on entity
        addEntityField(Parameter(
            name = "id", type = Type.Long
        ))

        addEntityField(Parameter(
            name = "name", type = Type.String
        ))

        addEntityField(Parameter(
            name = "anotherFeature", type = Type.CustomType(
                packageValue = "com.mctech.architecture.domain.feature_empty.entity",
                typeReturn = "FeatureEmpty"
            )
        ))


        // Create an use case that will call the repository and delegate it to the data sources and so on.
        addUseCase {
            UseCaseBuilder(
                name        = "LoadAllItemsCase",
                returnType  = Type.ListOfGeneratedEntity,
                isDaggerInjectable = false
            )
        }

        addUseCase {
            UseCaseBuilder(
                name        = "LoadItemDetailCase",
                returnType  = Type.ResultOf(Type.GeneratedEntity),
                parameters  = listOf(
                    Parameter(
                        name = "item",
                        type = Type.GeneratedEntity
                    ),
                    Parameter(
                        name = "simpleList",
                        type = Type.CustomType(
                            packageValue = "com.mctech.architecture.domain.feature_empty.entity",
                            typeReturn = "FeatureEmpty"
                        )
                    )
                ),
                isDaggerInjectable = false
            )
        }

        addLiveData {
            LiveDataBuilder(
                name = "items",
                type = Type.ListOfGeneratedEntity
            )
        }

        addLiveData {
            LiveDataBuilder(
                name = "userName",
                type = Type.String
            )
        }

        addComponentState {
            ComponentStateBuilder(
                name = "listEntities",
                type = Type.ListOfGeneratedEntity
            )
        }

        addUserInteraction {
            UserInteractionBuilder(
                name = "LoadList",
                connectedState = findStateByName("listEntities"),
                connectedUseCase = findUseCaseByName("LoadAllItemsCase")
            )
        }

        addUserInteraction {
            UserInteractionBuilder(
                name = "OpenDetails",
                parameters = listOf(
                    Parameter(
                        name = "item",
                        type = Type.GeneratedEntity
                    )
                ),
                connectedUseCase = findUseCaseByName("LoadItemDetailCase")
            )
        }
    }
}

Generated files

Domain Layer

• ComplexFeature.kt
• ComplexFeatureService.kt - With delegation methods of use cases
• LoadAllItemsCase.kt
• LoadItemDetailCase.kt

Data Layer

• ComplexFeatureDataSource.kt - With delegation methods of use cases
• LocalComplexFeatureDataSource.kt - With delegation methods of use cases
• RemoteComplexFeatureDataSource.kt - With delegation methods of use cases
• ComplexFeatureRepository.kt - With delegation methods of use cases
• ComplexFeatureAPI.kt - With delegation methods of use cases

Presentation Layer (New Module)

• settings.gradle - Add new module on the current project file.
• build.gradle
• AndroidManifest.xml
• strings.xml
• activity_complex_feature.xml
• fragment_complex_feature.xml
• ComplexFeatureActivity.kt - With delegation methods of LiveData
• ComplexFeatureFragment.kt - With delegation methods of LiveData
• ComplexFeatureViewModel.kt - With delegation methods of LiveData
• ComplexFeatureUserInteraction.kt

Roadmap

• Improve code (Yeah, I know the code is not good, but again, this library was a personal generator before it became open source) :P
• Make the generator easier to be used
• Improve the templates logic.
• Create an extension library and organize all existing functions.
• Create all unit tests.