What is KOIN?

A pragmatic lightweight dependency injection framework for Kotlin developers.

Written in pure Kotlin, using functional resolution only: no proxy, no code generation, no reflection.

Koin is a DSL, a light container and a pragmatic API

Official Website 👉 https://insert-koin.io

Latest News 🌐

• Follow us on Twitter for latest news: @insertkoin_io
• Koin developers on Medium: koin developers hub

Getting Help 🚒

Documentation:

• Getting Stared
• Documentation References

Any question about Koin usage?

• Come talk on slack #koin channel
• Post your question on Stackoverflow - #koin tag

Articles, Videos & other resources 🎉

Online resources about Koin - Talking about Koin

Reporting issues 🚑

Found a bug or a problem on a specific feature? Open an issue on Github issues

Contributing 🛠

Want to help or share a proposal about Koin? problem on a specific feature?

• Open an issue to explain the issue you want to solve Open an issue
• Come talk on slack #koin-dev channel
• After discussion to validate your ideas, you can open a PR or even a draft PR if the contribution is a big one Current PRs

Additional readings about basic setup: https://github.com/InsertKoinIO/koin/blob/master/CONTRIBUTING.adoc

Setup

Current Version

// latest stable
koin_version = '2.1.5'

Gradle

Jcenter

Check that you have the jcenter repository.

// Add Jcenter to your repositories if needed
repositories {
	jcenter()    
}

Dependencies

Pick one of your Koin dependency:

Gradle Plugin

buildscript {
    repositories {
        jcenter()
    }
    dependencies {
        classpath "org.koin:koin-gradle-plugin:$koin_version"
    }
}

apply plugin: 'koin'

Core features

// Koin for Kotlin
implementation "org.koin:koin-core:$koin_version"
// Koin extended & experimental features
implementation "org.koin:koin-core-ext:$koin_version"
// Koin for Unit tests
testImplementation "org.koin:koin-test:$koin_version"
// Koin for Java developers is now part of core
// implementation "org.koin:koin-java:$koin_version"

Android

// Koin for Android
implementation "org.koin:koin-android:$koin_version"
// Koin Android Scope features
implementation "org.koin:koin-android-scope:$koin_version"
// Koin Android ViewModel features
implementation "org.koin:koin-android-viewmodel:$koin_version"
// Koin Android Experimental features
implementation "org.koin:koin-android-ext:$koin_version"

AndroidX

// Koin AndroidX Scope features
implementation "org.koin:koin-androidx-scope:$koin_version"
// Koin AndroidX ViewModel features
implementation "org.koin:koin-androidx-viewmodel:$koin_version"
// Koin AndroidX Fragment features
implementation "org.koin:koin-androidx-fragment:$koin_version"
// Koin AndroidX Experimental features
implementation "org.koin:koin-androidx-ext:$koin_version"

Ktor

// Koin for Ktor Kotlin
implementation "org.koin:koin-ktor:$koin_version"

Quickstart

Declare a Koin module

Write with the Koin DSL what you need to assemble:

// Given some classes 
class Controller(val service : BusinessService) 
class BusinessService() 

// just declare it 
val myModule = module { 
  single { Controller(get()) } 
  single { BusinessService() } 
} 

Starting Koin

Use the startKoin() function to start Koin in your application.

In a Kotlin app:

fun main(vararg args : String) { 
  // start Koin!
  startKoin {
    // your modules
    modules(myModule)
  }
} 

In an Android app:

class MyApplication : Application() {
  override fun onCreate(){
    super.onCreate()
    // start Koin!
    startKoin {
      // Android context
      androidContext(this@MyApplication)
      // modules
      modules(myModule)
    }
  } 
} 

Talking about Koin

Articles

• Dagger is dead. Long live Koin
• Testing a Koin application with KotlinTest
• Ready for Koin 2.0
• Migration from Dagger2 to Koin
• From Dagger to Koin, a step by step migration guide
• Koin in Feature Modules Project
• A brief look at Koin on Android
• Bye bye Dagger
• Testing with Koin
• Painless Android testing with Room & Koin
• Unlock your Android ViewModel power with Koin
• Using dependency injection with Koin
• Koin + Spark = ❤️
• Push SparkJava to the next level (Kotlin Weekly issue 73, DZone.com )
• When Koin met Ktor ... (Kotlin Weekly issue 72)
• Android Dependency Injection – Why we moved from Dagger 2 to Koin?
• Moving from Dagger to Koin - Simplify your Android development - (Kotlin Weekly issue 66 & Android Weekly issue 282)
• Kotlin Weekly #64
• Insert Koin for dependency injection
• Better dependency injection for Android

Videos & Podcasts

• Dependency Injection from zero to hero with Koin, Kotliners 2019 & Budapest, Hungary
• Dependency Injection from zero to hero with Koin, AndroidMakers 2019 & Paris, France
• Simplify your Android development with Koin - Mobilization @ Lodz, Poland
• Talking Kotlin - Dependency injection with Koin
• L'injection de poireaux avec Koin - AndroidLeaks ep42 (French)
• Insert Koin. Mobile Fest 2018, Kiev, Urkaine (Russian)

Koin Developers Hub

• Ready for Koin 2.0
• News from the trenches, What's next for Koin?
• Koin 1.0.0 Unleashed
• Opening Koin 1.0.0 Beta
• On the road to Koin 1.0
• Koin 0.9.2 — Maintenance fixes, new branding, roadmap for 1.0.0 & some other nice announces
• Koin 0.9.1 - Bug fixes & Improvments
• Koin 0.9.0 - Getting close to stable
• Unlock your Android ViewModel power with Koin
• koin 0.8.2 Improvements bugfixes and crash fix
• Koin release 0.8.0

Contributors

This project exists thanks to all the people who contribute. [Contribute].

OpenCollective

Backers

Thank you to all our backers! 🙏 [Become a backer]

Sponsors

Support this project by becoming a sponsor. Your logo will show up here with a link to your website. [Become a sponsor]