[Feature request] ContributesAndroidInjector with FragmentFactory lifecycles

DaggerFragment used with ContributesAndroidInjector works fine. However, with the introduction of FragmentFactory, field injection is not needed anymore and constructor injection can be used for fragments. While this works fine, subcomponent lifecycle (w.r.t fragment) is missed and in some cases fragment can stay alive even and reused across back stack navigation (within the same activity instance/parent component).

This request to support some kind of scope/life cycle for multibindings used by the fragment factory injector.

Current:

@Module
abstract class FragmentBindingModule {

   @ContributesAndroidInjector( modules = [MainFragmentModule::class] )
    abstract fun mainFragment() : MainFragment
}

New:

@Module
abstract class FragmentModule {

    @Binds
    @IntoMap
    @FragmentKey( MainFragment::class )
    // Associate MainFragmentModule to fragment lifecycle
    abstract fun bindMainFragmentFragment( fragment: MainFragment) : Fragment
}

[nlgtuankiet]

In a nutshell, you still need to write subcomponent manually. The approaches to perform cotructor injection on Fragment class while still maintain scoping is described here: https://medium.com/@nlg.tuan.kiet/fragmentfactory-and-how-to-maintain-scoping-with-dagger-2-d9d16c892626 Sample project: https://github.com/nlgtuankiet/FragmentFactory

class TasksFragment(
    val viewModelFactory: TasksViewModel.Factory,
    private val messageManager: MessageManager,
    private val tasksController: TasksController,
    private val navigator: TasksNavigator
) : Fragment()

@Subcomponent(
    modules = [
        TasksComponent.Provision::class,
        TasksBindingModule::class
    ]
)
@FragmentScope
interface TasksComponent : FragmentComponent<TasksFragment> {
    @Subcomponent.Factory
    interface Factory : FragmentComponent.Factory<TasksComponent>

    @Module
    object Provision {
        @JvmStatic
        @Provides
        @FragmentScope
        fun fragment(
            holder: Holder<TasksFragment>,
            messageManager: MessageManager,
            viewModelFactory: TasksViewModel.Factory,
            tasksController: TasksController,
            navigator: TasksNavigator
        ) = TasksFragment(
            messageManager = messageManager,
            viewModelFactory = viewModelFactory,
            tasksController = tasksController,
            navigator = navigator
        ).also { holder.instance = it }

        @JvmStatic
        @Provides
        @FragmentScope
        fun holder() = Holder<TasksFragment>()
    }
}

class BaseFragmentFactory(
    private val providers: Map<Class<out Fragment>, @JvmSuppressWildcards Provider<FragmentComponent.Factory<*>>>
) : FragmentFactory() {
    override fun instantiate(classLoader: ClassLoader, className: String): Fragment {
        val fragmentClass = classLoader.loadClass(className)
        return providers.entries.find { it.key.isAssignableFrom(fragmentClass) }
            ?.value?.get()?.create()?.fragment() ?: super.instantiate(classLoader, className)
    }
}

[TheReprator]

@nlgtuankiet, i had tried to implement your code, it’ working fine, but when i want to create a new separate component, it give me error,

https://github.com/nlgtuankiet/todo-sample/issues/2,

Raised the issue, please have a look at it

Please find the project link to reproduce the error, https://github.com/TheReprator/BugReproduceFragmentFactory