I’m having some trouble refactoring an Android cod...

# android

[Tim Malseed]

I’m having some trouble refactoring an Android codebase to make use of Square’s @AssistedInject with Dagger 2, though I’ve used it with success in other projects..

It seems as though the `@AssistedInject.Factory Factory`is not being provided its non-assisted properties. I don’t quite have the terminology to describe this problem, so I’ll show rather than tell:

[Tim Malseed]

The error I’m getting (abridged):

MissingBinding (BridgeSelectionController), FragmentManager cannot be provided without @Provides method. A binding with matching key exists in component FragmentComponent

javax.inject.Provider<androidx.fragment.app.FragmentManager> is injected at
          <http://au.com|au.com>.smartsnugg.ui.screens.bridge_onboarding.bridgeselection.BridgeSelectionNavigator_AssistedFactory.<init>(fragmentManager)

The thing is, fragmentManager is provided via `NavigatorModule`:

class BridgeSelectionController { ...

    @Inject
    lateinit var navigatorFactory: BridgeSelectionNavigator.Factory

    ...

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)

        (context!!.applicationContext as SmartSnuggApplication).appComponent
            .plus(ActivityModule(activity!!))
            .plus(NavigatorModule(fragmentManager!!))
            .inject(this)

[Tim Malseed]

BridgeSelectionNavigator looks like so:

class BridgeSelectionNavigator @AssistedInject constructor(
    fragmentManager: FragmentManager,
    @Assisted private val subject: Subject
) : BaseNavigator(fragmentManager), BridgeSelectionContract.Navigator {

    @AssistedInject.Factory
    interface Factory {
        fun create(subject: Subject): BridgeSelectionNavigator
    }

[Tim Malseed]

So, my thinking is that BridgeSelectionController uses plus NavigatorModule to construct a component that can provide an instance of FragmentManager.

Then, BridgeSelectionNavigator.Factory is injected, and the required property FragmentManager should be supplied accordingly.

[Tim Malseed]

What gives? If I made fragmentManager an @Assisted property in the BridgeSelectionNavigator Factory, and then used @Inject fragmentManager in BridgeSelectionController, I’d be able to pass the fragmentManager to the Factory.create() method. But Dagger should do this for me - I should only have to provide @Assisted properties myself, Dagger should be able to provide the rest.

[Barco]

What do your Component and Module look like?

[Tim Malseed]

`FragmentComponent`:

@FragmentScope
@Subcomponent(modules = [NavigatorModule::class, PresenterModule::class])
interface FragmentComponent {

...

    fun inject(target: BridgeSelectionController)

...
}

[Tim Malseed]

NavigatorModule (I apologise for this mess):

@Module(includes = [NavigatorModule.AbsNavigatorModule::class])
class NavigatorModule(
    private val fragmentManager: FragmentManager,
    @Named(CHILD_FRAGMENT_MANAGER) private val childFragmentManager: FragmentManager? = null,
    @Named(PARENT_FRAGMENT_MANAGER) private val parentFragmentManager: FragmentManager? = null
) {

    @Provides
    fun provideFragmentManager(): FragmentManager {
        return fragmentManager
    }

    @Named(CHILD_FRAGMENT_MANAGER)
    @Provides
    fun provideChildFragmentManager(): FragmentManager? {
        return childFragmentManager
    }

    @Named(PARENT_FRAGMENT_MANAGER)
    @Provides
    fun provideParentFragmentManager(): FragmentManager? {
        return parentFragmentManager
    }

    @Provides
    fun provideNavigator(): Navigator {
        return BaseNavigator(fragmentManager)
    }

    @Provides
    @Named(PARENT_NAVIGATOR)
    fun provideParentNavigator(): Navigator? {
        return parentFragmentManager?.let { BaseNavigator(parentFragmentManager) }
    }

...

[Tim Malseed]

(The interesting part of NavigatorModule , IMO is just:

@Provides
    fun provideFragmentManager(): FragmentManager {
        return fragmentManager
    }

(It does indeed provide a FragmentManager)

[Barco]

I don’t see where you are referencing the generated module

[Barco]

as detailed here: https://github.com/square/AssistedInject#usage-with-dagger-2

[Tim Malseed]

Where I’m referencing the AppAssistedModule?

[Tim Malseed]

In AppComponent:

@Singleton
@Component(modules = [AppModule::class, AppAssistedModule::class, NetworkingModule::class, EventModule::class])
interface AppComponent {
...

[Barco]

The generated module should have the format AssistedInject_YourModule

[Barco]

@You should have at least one module annotated with @AssistedModule , which will indicate to Dagger to generate a module called AssistedInject_YourModule , which in turn will satisfy the dependency on your Factory

[Barco]

Then you just include this generated module in your normal module using the includes parameter in the @Module annotation.

[Tim Malseed]

Yes, I am doing this

[Tim Malseed]

@AssistedModule
@Module(includes = [AssistedInject_AppAssistedModule::class])
abstract class AppAssistedModule

[Tim Malseed]

I don’t believe the problem I’m having is due to a misconfiguration of AssistedInject

[Ahmed Ibrahim]

From the error that you're getting, I think you already have another`@Provides` method that provides FragmentManager somewhere in your graph. If I were you I would check `ActivityModule`otherwise I would check the parent component of the FragmentComponent since it is a @Subcomponent

[Tim Malseed]

OK, thanks for the tip. It’s late here, but I’ll have a look tomorrow