Dagger + ViewModel, first iteration

ApplicationComponent.kt

@Singleton
@Component
class ApplicationComponent {
    fun myViewModelProvider(): Provider<MyViewModel>
}

fragment.kt

class MyFragment: Fragment() {
    lateinit var viewModel: MyViewModel
    
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        
        val component = (requireActivity().application as MyApplication).component
        
        viewModel = createViewModel { component.myViewModelProvider().get() }
    }
}

MyViewModel.kt

class MyViewModel @Inject constructor(): ViewModel()  {
}

viewmodel-helpers.kt

inline fun <reified T: ViewModel> ViewModelStoreOwner.createViewModel(crossinline factory: () -> T): T = T::class.java.let { clazz ->
    ViewModelProvider(this, object: ViewModelProvider.Factory {
        override fun <T : ViewModel?> create(modelClass: Class<T>): T {
            if(modelClass == clazz) {
                @Suppress("UNCHECKED_CAST")
                return factory() as T
            }
            throw IllegalArgumentException("Unexpected argument: $modelClass")
        }
    }).get(clazz)
}

@Zhuinden you should be able to have a single createViewModel if you use ViewModelStoreOwner as the receiver.

put all together you landed on almost exactly the way i've been doing it for almost 2 years. 😆
https://gist.github.com/trevjonez/0535c396b7b79a8fa85827f79f543c52

Thanks for the note, I was thinking if there are any downsides but I can't see one. This is a great addition and therefore updated the gist. Thanks!

this code doesn't compile :-) Where does the clazz property come from? Also this line if(modelClass == T::class.java) { does not compile, because in that context T is not reified. And you cannot use reified in the overriding function. Also it uses deprecated ViewModelProviders

I believe this is the working and up-to-date version:

inline fun <reified T: ViewModel> ViewModelStoreOwner.createViewModel(crossinline factory: () -> T): T {
    val clazz = T::class.java
    return ViewModelProvider(this, object : ViewModelProvider.Factory {
        override fun <T : ViewModel?> create(modelClass: Class<T>): T {
            if (modelClass == clazz) {
                @Suppress("UNCHECKED_CAST")
                return factory() as T
            }
            throw IllegalArgumentException("Unexpected argument: $modelClass")
        }
    }).get(clazz)
}

That's what I get for trying to remove a .let { clazz - > and make the example a bit clearer, but do that only in a Gist 🤔 I'll just copy the real thing when I'm near my pc

Thanks for letting me know, I've just replaced it with the real code instead. Now it can't not work.

I'd also suggest to update the example to not use ViewModelProviders . It's deprecated: https://developer.android.com/reference/androidx/lifecycle/ViewModelProviders

that's what I get for copy-pasting from Stack Overflow from an answer I should clearly update as it's like a year old 😅

But yes, you are right. Now I've updated both.