Dependency injection inside extension function

Question

Is there a way to inject an object inside an extension function or a global function using DI framework in Android Kotlin?

I use this function in many places. So I do not want to pass a parameter every time.

DI framework can be any of Koin, Hilt, Dagger2, or others.

Something like that:

fun Context.showSomething() {
 val myObject = inject()
 showToast(myObject.text)
}

score 1 · Answer 1 · answered Aug 18 '21 at 14:16

1

Instead of thinking about using Inject you could pass it as a parameter:

fun Context.showSomething(myObject: String) {
 showToast(myObject.text)
}

answered Aug 18 '21 at 14:16

DoctorWho

1,044
11
34

1

I use this function in many places. So I do not want to pass a parameter every time. – Yeldar Nurpeissov Aug 18 '21 at 15:36
There is very little choice but to either pass in a parameter, or put this method on a class that is constructed instead of on a top-level extension. – Louis Wasserman Aug 18 '21 at 18:28

score 0 · Answer 2 · answered Aug 18 '21 at 14:19

0

With Koin you can do like this,

fun Context.showSomething() {
  val myObject = GlobalContext.get().get()
  showToast(myObject.text)
}

but it's totally not recommended way of using it.

answered Aug 18 '21 at 14:19

Aleksei Potapkin

1,021
12
23

Barry Fruitman · Answer 3 · 2022-09-30T22:21:15.470

I use my app component to inject into extension methods. For example, to use MyInjectableClass in an extension method:

// Your app component
@Component
interface ApplicationComponent {
    fun myInjectable(): MyInjectableClass
}

// Your app class
class MyApplication: Application() {
    companion object {
        var appComponent: ApplicationComponent? = null
    }

    override fun onCreate() {
        appComponent = DaggerAppComponent.create()
    }
}

// Ext.kt file

private val injectable: MyInjectableClass?
    get() = MyApplication.appComponent?.myInjectable()

fun Foo.extension() {
    injectable?.bar()
    // huzzah!
}

Of course you still need to provide the @Provides or @Binds method for MyInjectableClass.

Dependency injection inside extension function

3 Answers3