Injected ViewModel Provider

This is a small lib to use easily use Android's ViewModels with a depedency injection framework like dagger. You obtain a ViewModel from a javax.inject.Provider instead of a ViewModelProvider.Factory.

[Deprecated]

There are now improved viewmodel functions in androidx which means this library really isn't needed anymore. https://developer.android.com/topic/libraries/architecture/viewmodel/viewmodel-factories

Usage

From Java

Download

implementation("me.tatarka.injectedvmprovider:injectedvmprovider:3.0.0")

Usage

Set up your ViewModel

public class MyViewModel extends ViewModel {
    private final MyDependency source;

    @Inject
    public MainViewModel(MyDependency source) {
        this.source = source;
    }
}

Inject your ViewModel provider into the desired Fragment or Activity

public class MyActivity extends AppCompatActivity {

    @Inject
    Provider<MyViewModel> vmProvider;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        ...
        MyViewModel vm = InjectedViewModelProvider.of(this).get(vmProvider);
    }
}

If you have a factory, you can inject that instead. This is useful for passing in intent arguments to the view model, and/or with assisted injection. For the key, you can either pass the factory instance or the view model class.

class MyActivity extends ComponentActivity {
    @Inject
    MyViewModel.Factory vmFactory;
    
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        MyViewModel vm = InjectedViewModelProvider.of(this).get(vmFactory, factory -> factory.create("arg"));
        MyViewModel vm2 = InjectedViewModelProvider.of(this).get(MyViweModel.class, () -> vmFactory.create("arg"));
    }
} 

From Kotlin

Download

implementation 'me.tatarka.injectedvmprovider:injectedvmprovider-ktx:3.0.0'
// or if you are using fragments
implementation 'me.tatarka.injectedvmprovider:injectedvmprovider-fragment-ktx:3.0.0'

Usage

Set up your ViewModel

class MyViewModel @Inject constructor(val source: MyDependency): ViewModel()

Use the viewModels delegate to obtain a view model from an injected provider.

class MyFragment @Inject constructor(val vmProvider: Provider<MyViweModel>) {
    val vm by viewModels(vmProvider)
}

If you have field injection or are using a factory, you pass a lambda to view model instead. This lambda will provide a SavedStateHandle that you may pass along to your view model.

class MyActivity: ComponentActivity {
    @Inject
    latinit var vmProvider: Provider<MyViewModel>
    @Inject
    latinit var vmFactory: MyViewModel.Factory
    
    val vm by viewModel { vmProvider.get() }
    val vm2 by viewModel { handle -> vmFactory.create(handle) }
    
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        inject(this)
    }
}