Kotlin-js-di

Dependency injection library for kotlin.js. Supports multiple modules, scopes and late bindings.

This library is in beta. Api is not comfortable to use yet and will change in future.

Integration

Gradle:

    buildscript {
        ext.kotlin_js_di_version='0.0.5'
    }

    allprojects {
        repositories {
            maven { url 'https://jitpack.io' }
        }
    }
    
    dependencies {
        compile "com.github.diklimchuk:Kotlin-js-di:$kotlin_js_di_version"
    }

Npm:

    npm i kotlin-js-di

Getting started

Modules

Modules determine how object will be created:

// Define classes
class Router(rootUrl: String)
class Application(router: Router)
// Modules can provide dependencies by name
val ROUTER_MODULE = createDiModule {
    it provides { Router(get("RootUrl")) } with "Router"
    it binds "/app" with "RotUrl"
}
// Modules can take dependencies from other modules.
val APPLICATION_MODULE = createDiModule {
    it scopes { Application(get()) }
}

All dependencies in module will be lazily evaluated.

Modules can create object in 3 ways:

• provides will create new instance each time
• scopes will instantiate object once until module scope won't be released
• binds will use the same instance every time. It is not allowed have dependencies and can be used to skip braces around.

Components

Components can provide dependencies:

// Define component
class MainComponent : DiComponent(APPLICATION_MODULE, ROUTER_MODULE)

// Create component
val component = MainComponent()
// Then retrieve all dependencies you need
val app: Application = component.get()
val router: Router = component.get()
val rootUrl: String = component.get("RootUrl")

Subcomponents

Subcomponent allow dependencies to live for a period less than Singleton:

class UserProvider
// Define scope (i.e for a page): 
val pageScope = DiScope.SINGLETON.createChild()
// Define subcomponent in a module
val PAGE_MODULE = createDiModule {
    it hasSubcomponents {
        it add DiComponent(createDiModule {
            it scopes UserProvider()
        }) scoped pageScope
    }
}
// Add Module to main component
val component = DiComponent(PAGE_MODULE)
// Open scope:
fun onPageOpened() {
    val subcomponent = component.openScope(pageScope)
    // Inject dependencies
    val userProvider: UserProvider = subcomponent.get()
    // Close scope when it's no longer needed
    subcomponent.release()
}

Lateinit bindings

Allow to add object to dependency graph at runtime

class NoteProvider(noteId: Int)
val pageScope = DiScope.SINGLETON.createChild()
val MODULE = crateDiModule {
    it hasSubcomponents {
        it add DiComponent(createDiModule {
            it scopes NoteProvider(get("NoteId"))
        })
    }
}
fun onPageOpened(noteId: Int) {
    val subcomponent = component.openScope(pageScope) {
        // You can provide dependencies in runtime. They will be bound to opened scope.
        it binds noteId with "NoteId"
    }
    val noteProvider: NoteProvider = subcomponent.get()
    subcomponent.release()
}

TODO

• Log error if both component and subcomponent failed dependency cretion
• Allow only lateinit values
• Better error descriptions
• Logging