Meteor KMP

Meteor is a simple framework that helps you to create application using the MVI architecture. It provides a robust structure for organizing your code and separating concerns. Additionally, Meteor integrates with Kotlin Coroutine that helps you to write asynchronous and concurrent code.

Features

Meteor follows the Model-View-Intent (MVI) architecture pattern.
It provides a unidirectional data flow (UDF), allowing you to handle state changes and propagate them to the UI efficiently.
Supports Kotlin Coroutines: asynchronous and concurrent code in a more concise and structured way.
Meteor supports Kotlin Multiplatform, allowing you to share code across multiple platforms.
Easy to test (integration and unit tests).
Additional features like common use cases, state flow, view model and logger.

Documentation 📖

Setup

Add the dependency below into your module's build.gradle.kts file:

// It includes viewmodel, stateflow and core components.
implementation("io.github.behzodhalil:meteor-mvi:<latest-version>")
// If only need common use case
implementation("io.github.behzodhalil:meteor-usecase:<latest-version>")
// For testing
testImplementation("io.github.behzodhalil:meteor-test:<latest-version>")

Define the contract

data class CountState(
    val count: Int = 0
)

sealed interface CountWish {
    object Increase : CountWish
    object Decrease : CountWish
    object Reset : CountWish
    object ZeroValue : CountWish
}

sealed interface CountEffect {
    data class Failure(val message: String) : CountEffect
}

State represents the current state of your application. Effects are a way to handle side effects in Meteor. Side effects can include operations such as making network requests, updating a database, displaying UI messages, or triggering external actions. A Wish in Meteor represents an action or an intention to change the state of the application.

Create the ViewModel

Define a ViewModel class, such as MainViewModel, that extends CommonViewModel with the appropriate state, wish, and effect types:

class MainViewModel : CommonViewModel<CountState, CountWish, CountEffect>() {
      // ....
}

Inside your ViewModel, override the store property by creating a Meteor store using the createMeteor function and providing the necessary configurations:

    override val store: Store<CountState, CountWish, CountEffect> = createMeteor(
        configs = MeteorConfigs.build {
            initialState = CountState.Empty
            storeName = "MainViewModel"
            reducer = CountReducer
            middleware = CountMiddleware
        }
    )

Define properties for effect and state in your ViewModel, which will expose the effect and state as CommonFlow and CommonStateFlow, respectively:

val effect: NonNullCommonFlow<CountEffect> = store.effect.asCommonFlow()
val state: NonNullCommonStateFlow<CountState> = store.state.asCommonStateFlow()

Define Reducer and Middleware

Create an object / class , such as CountReducer, that implements the Reducer interface with the appropriate state, wish, and effect types:

    object CountReducer : Reducer<CountState, CountWish, CountEffect> {
        override fun reduce(state: CountState, wish: CountWish): Change<CountState, CountEffect> {
            return when (wish) {
                CountWish.Decrease -> {
                    expect { state.copy(count = state.count - 1) }
                }
                CountWish.Increase -> {
                    expect { state.copy(count = state.count + 1) }
                }
                CountWish.Reset -> {
                    expect { state.copy(count = 0) }
                }
                CountWish.ZeroValue -> {
                    effect {
                        CountEffect.Failure("The value is zero")
                    }
                }
            }
        }

    }

Using in Fragment / Compose

viewModel.state.onEach { state ->
    // Handle the state
}.launchIn(lifecycleScope)

viewModel.effect.onEach { effect ->
    // Handle the effect, such as displaying a toast message or triggering an action
}.launchIn(lifecycleScope)

Inspired by

Credits

kmp-viewmodel

License

This project is licensed under the Apache License, Version 2.0 - see the license file for details

getspherelabs/meteor-kmp