🥥 Cokoin

Injection library for Compose (Multiplatform and Jetpack), Koin wrapper. It uses @Composable functions to configure KoinContext.

Installation

Library is hosted on Maven Central. Add following the packages to your module build.gradle.kts or build.gradle:

dependencies {
    implementation("dev.burnoo:cokoin:1.0.0")
    implementation("dev.burnoo:cokoin-android-viewmodel:1.0.0") // for Androidx ViewModel
    implementation("dev.burnoo:cokoin-android-navigation:1.0.0") // for Compose Navigation

    // REMOVE "org.koin:koin-androidx-compose:X.Y.Z" if you were using it
}

Usage

The library is using Koin's Application and Modules. The Koin documentation can be found here: https://insert-koin.io/.

The core library contains @Composable Koin function, which is used to configure Koin application. It can be used with @Preview.

val appModule = module {
    factory { "Hello, DI!" }
}

@Preview
@Composable
fun App() {
    Koin(appDeclaration = { modules(appModule) }) {
        val text = get<String>()
        Text(text)
    }
}

Scopes

Scopes are created by wrapping composables in @Composable KoinScope:

data class A(val value: String)

val scopedModule = module {
    scope<ScopeTypeA> {
        scoped { A("scopeA") }
    }
    scope<ScopeTypeB> {
        scoped { A("scopeB") }
    }
}

@Preview
@Composable
fun Test() {
    Koin(appDeclaration = { modules(scopedModule) }) {
        Column {
            KoinScope(getScope = { createScope<ScopeTypeA>() }) {
                Text(get<A>().value)
            }
            KoinScope(getScope = { createScope<ScopeTypeB>() }) {
                Text(get<A>().value)
            }
        }
    }
}

ViewModel

dev.burnoo:cokoin-android-viewmodel:x.y.z

Call getViewModel to obtain ViewModel inside @Composable:

class MainViewModel : ViewModel() {
    val data = "Hello, DI!"
}

private val viewModelModule = module {
    viewModel { MainViewModel() }
}

@Composable
fun ViewModelSample() {
    Koin(appDeclaration = { modules(viewModelModule) }) {
        val viewModel = getViewModel<MainViewModel>()
        Text(viewModel.data)
    }
}

getViewModel supports Koin's injection parameters and SaveStateHandle. Advanced examples can be found here.

Compose Navigation

dev.burnoo:cokoin-android-navigation:x.y.z

First replace NavHost with KoinNavHost:

@Composable
fun Sample() {
    val navController = rememberNavController()
    Koin(appDeclaration = { modules(viewModelModule) }) {
        KoinNavHost(navController, startDestination = "1") {
            composable("1") {
                Screen1()
            }
        }
    }
}

Then use getNavController and getNavViewModel inside composable screen.

@Composable
fun Screen1() {
    val navController = getNavController()
    Button(onClick = { navController.navigate("2") }) {
        val navViewModel = getNavViewModel<MainViewModel>()
        //...
    }
}

If you don't want to wrap navigation with KoinNavHost, you can achieve similar results with getViewModel using viewModelStoreOwner parameter:

@Composable
fun Screen1(navController: NavController) {
    Button(onClick = { navController.navigate("2") }) {
        val viewModel = getViewModel<MainViewModel>(
            viewModelStoreOwner = navController.getBackStackEntry("root")
        )
        //...
    }
}

License

Copyright 2021 Bruno Wieczorek

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

   http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.