Is there a way to pass additional argument to my custom AndroidViewModel
constructor except Application context.
Example:
public class MyViewModel extends AndroidViewModel {
private final LiveData<List<MyObject>> myObjectList;
private AppDatabase appDatabase;
public MyViewModel(Application application, String param) {
super(application);
appDatabase = AppDatabase.getDatabase(this.getApplication());
myObjectList = appDatabase.myOjectModel().getMyObjectByParam(param);
}
}
And when I want to user my custom ViewModel
class I use this code in my fragment:
MyViewModel myViewModel = ViewModelProvider.of(this).get(MyViewModel.class)
So I don't know how to pass additional argument String param
into my custom ViewModel
. I can only pass Application context, but not additional arguments. I would really appreciate any help. Thank you.
Edit: I've added some code. I hope it's better now.
You need to have a factory class for your ViewModel.
public class MyViewModelFactory implements ViewModelProvider.Factory {
private Application mApplication;
private String mParam;
public MyViewModelFactory(Application application, String param) {
mApplication = application;
mParam = param;
}
@Override
public <T extends ViewModel> T create(Class<T> modelClass) {
return (T) new MyViewModel(mApplication, mParam);
}
}
And when instantiating the view model, you do like this:
MyViewModel myViewModel = ViewModelProvider(this, new MyViewModelFactory(this.getApplication(), "my awesome param")).get(MyViewModel.class);
For kotlin, you may use delegated property:
val viewModel: MyViewModel by viewModels { MyViewModelFactory(getApplication(), "my awesome param") }
There's also another new option - to implement HasDefaultViewModelProviderFactory
and override getDefaultViewModelProviderFactory()
with the instantiation of your factory and then you would call ViewModelProvider(this)
or by viewModels()
without the factory.