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Inject into Fragment

Koject provides additional support for injecting into Fragments.

Setup for Fragment​

The following dependency is required to take advantage of the additional support.

dependencies {
    implementation("com.moriatsushi.koject:koject-android-fragment:1.3.0")
}

Please also refer to the Setup document.

Basic usage​

You can use the Fragment.inject() or Fragment.lazyInject() methods to inject any provided type.

@Provides
@Singleton
class Repository

@Provides
class Controller(
    private val repository: Repository
)
class MyFragment: Fragment {
    val controller: Controller by lazyInject()
}

Inject Fragment into other types​

Koject defines the @FragmentComponent and adding this annotation restricts it to be injectable only to Fragment or FragmentComponent types.

@FragmentComponent
class FragmentHelper
@FragmentComponent
class FragmentHelperHolder(
    val helper: FragmentHelper // can be injected
)
class MyFragment: Fragment {
    val helper: FragmentHelper by lazyInject() // can be injected
}

You can inject Fragment into FragmentComponent types.

@FragmentComponent
class FragmentHelper(
    val fragment: Fragment // can be injected
)

Inject Activity / Context​

The following three types of Activities are also available for FragmentComponent types.

  • androidx.fragment.app.FragmentActivity
  • androidx.activity.ComponentActivity
  • android.app.Activity

You can use them like this:

@FragmentComponent
class FragmentHelper(
    val activity: ComponentActivity // can be injected
)

When using Activity, be careful to inject after the Fragment is attached.

class MyFragment: Fragment() {
    val helper: Fragment = inject() // error!
    val helper: Fragment by lazyInject() // can be injected

    override fun onAttach(context: Context) {
        super.onAttach(context)
        
        val helper: Fragment = inject() // can be injected
    }
}

You can also inject android.content.Context by adding an @ActivityContext qualifier.

@FragmentComponent
class FragmentHelper(
    @ActivityContext
    val context: Context // activity's context
)

Inject Fragment's CoroutineScope​

The FragmentComponent type can also inject an fragment-scoped CoroutineScope and fragment-view-scoped CoroutineScope. Use @FragmentCoroutineScope qualifier and @FragmentViewCoroutineScope qualifier respectively.

@FragmentComponent
class FragmentHelper(
    @FragmentCoroutineScope
    val scope: CoroutineScope, // same as Fragment.lifecycleScope
    @FragmentViewCoroutineScope
    val viewScope: CoroutineScope, // same as Fragment.viewLifecycleOwner.lifecycleScope
)
LINK

Check the Android components documentation for all available components for Android.