Android MVVM Generator

Pre-requisites

• Project assumes that you use Hilt, Retrofit, Kotlin, Flows, Jetpack ViewModel and MVVM with UseCase layer.

• Import file_templates.zip as intelliJ settings file. It only imports file templates, so rest of your settings remain intact. (How to)

• Copy some base files in your desired directory, which include:

  • NetworkProvider sets up retrofit instance, you can replace with your own
  • BaseUseCase interface enforces SRP by providing 1 method that works on 1 input and 1 output.
  • BaseService has api call boilerplate, including default error messages mapped to http codes
  • Resource sealed class to map network response to Data for success else Error
  • StringResourceProvider is wrapper around strings.xml resource that is declared in its module
  • dependencies.gradle file has all the dependencies needed, this is then imported in build.gradle (app)
  • Setup some dependencies project wide using build.gradle (project) and module wide build.gradle (app)

  You can always replace/edit these as per your requirements.

Usage

• Create a package for feature in your desired package e.g. login
• Right click on target feature package, goto New then click New Feature, enter name when prompt appears
• Name in New Feature is case sensitive, e.g. Login, generated classes will be case sensitive with capital L- LoginApi, LoginUseCase etc.
• You will get all the classes generated!

Few more steps:

• Since base classes are completely subjective to their creation and placement, you will have to add some import statements.
• Goto generated ViewModel, UseCase and ApiService classes and add imports for base/common classes. (takes <10 seconds).
• Voila ! You have a feature skeleton ready to work on.

Generated Classes

<> replaces your generated feature name

• <>Api - Retrofit API end point class
• <>Service - Network call logic, uses <>Api
• <>UseCase - Use case to contain pure logic for data transformation/manipulation
• <>ViewModel - ViewModel with basic structure having reference to use case and some livedata declared
• <>Fragment - Empty Fragment
• <>Request - Model for UseCase input, there is room for better naming convention here.
• <>State - Model for UseCase output, again, there is room for better naming convention here.
• <>RequestDto - Model for request data in API call. This is json annotated to be used with Moshi.
• <>Response - Model for response object, this is json annotated to be used with Moshi.
• <>Bindings - DI bindings for Service and UseCase classes/interfaces
• <>Module - DI module method to create <>Api instance using retrofit instance discussed in Pre-requisites.

Extensibility

While this is pretty specific, it very easy to edit or update templates

• Goto Preferences in you IntelliJ (dependending on the OS, options may change), select File and Code Templates and scroll down in Files section.
• You will see there custom templates as mentioned in the image.
• You can add, edit, remove or even create an entirely new set of templates from this.
• This uses Apache Velocity langauage which is also mentioned in this prompt as VTL.
• This is fairly simple, declarative, yet very powerful templating language. You can almost achieve everything that a code generator can using this templating engine.

Disclaimer

• This does not in any way, ask you to implement or design apps/solutions with a preference. This might be 1 out of many ways to do things.
• Do not expect this project to work 100% perfectly 100% of the time.
• This is licensed with Apache 2.0