I am new to android app development. Please help. I want to get navigation fragment arguments in my view model class directly. I am using data-binding.

Here is my nav fragments argument

<fragment>
          ......
           ..
        <action
            android:id="@ id/action_update_to_listOfStudentFragment"
            app:destination="@id/list_fragment" />
        <argument
            android:name="currentStudent"
            app:argType="com.example.school.model.Student" />
    </fragment>

When I click on my recycler view item I pass the argument object with navigation action. So I set on click listener in adapters onbind function. I am passing student objects as arguments.

holder.itemLayoutBinding.root.setOnClickListener {
        val action = ListOfStudentFragmentDirections.actionListOfStudentFragmentToUpdate(currentStudent)
        holder.itemLayoutBinding.root.findNavController().navigate(action)
    }

My View Model is here. I want to know another thing: I am using AndroidViewModel here for database context. Is there any other way to avoid AndroidViewModel? I want to use ViewModel but the view model does not provide context.

    class MainModleView(application: Application) : AndroidViewModel(application) {

val getAllStudentData: LiveData<List<Student>>
    val repository: Repository

    val inputName = MutableLiveData<String>()
    val inputAge = MutableLiveData<String>()

    init {
        val studentDao: StudentDao = StudentDatabase.getAllData(application).studentDao()
        repository = Repository(studentDao)
        getAllStudentData = repository.getAllData

    }

So in View-Model's live data, I want to set the inputName and inputAge value from fragments arguments. Here is a sample of what I want.

inputName.value = fragmentsarugments.name //arguments pass a model object from recyclerview on click function
inputAge.value = fragmentsarugments.age

Please give me a solution. I only want to get fragment's argument in my ViewModel.

CodePudding user response：

Use a ViewModelProviderFactory for custom arguments. You can pass your arguments directly when initializing your viewmodel.

class MeterListViewModelFactory implements ViewModelProvider.Factory {
    private final MainRepository mainRepository;
    private final Bundle mExtras;
    private final Context context;

    public MeterListViewModelFactory(Context context, MainRepository mainRepository, Bundle mExtras) {
        this.mainRepository = mainRepository;
        this.context = context;
        this.mExtras = mExtras;
    }

    @NonNull
    public <T extends ViewModel> T create(@NonNull Class<T> modelClass) {
        if (modelClass.equals(MeterListViewModel.class))
            //noinspection unchecked
            return (T) new MeterListViewModel(context,mainRepository, mExtras);
        return super.create(modelClass);
    }
}

Create viewmodel like this

 viewModel = new ViewModelProvider(this, new MeterListViewModelFactory(LdpApplication.getAppContext(), new MainRepository(new MainRemoteDataSource()
            , new MainCachedDataSource(AppRoomDatabaseImpl.getInstance(requireContext()).getAppDatabase())), getArguments())).get(MeterListViewModel.class);

Then you can initialize your variables from args passed

public MeterListViewModel(Context context, MainRepository mainRepository, Bundle mExtras) {
        this.mainRepository = mainRepository;
        mContext = context;
        if (mExtras != null && mExtras.containsKey(AppConstants.K_METER_TYPE))
            metersType.setValue((MetersType) mExtras.getSerializable(AppConstants.K_METER_TYPE));
        if (mExtras.getString(AppConstants.K_COMMISSION_FILTER).equalsIgnoreCase(context.getString(R.string.txt_all))) {
            lastSelectedPosition = 0;
        } else if (mExtras.getString(AppConstants.K_COMMISSION_FILTER).equalsIgnoreCase(context.getString(R.string.txt_sign_off_pending))) {
            lastSelectedPosition = 1;
        } else if (mExtras.getString(AppConstants.K_COMMISSION_FILTER).equalsIgnoreCase(context.getString(R.string.txt_sign_off_pending_for_approval))) {
            lastSelectedPosition = 2;
        } else if (mExtras.getString(AppConstants.K_COMMISSION_FILTER).equalsIgnoreCase(context.getString(R.string.txt_sign_off_done))) {
            lastSelectedPosition = 3;
        } else {
            lastSelectedPosition = 4;
        }
        selectedFilterItem = mExtras.getString(AppConstants.K_COMMISSION_FILTER);
        commissionFilters = HelperClass.getCommissionFilters(context);
        this.loadMeters(null, true);

    }

CodePudding user response：

pass arguments to viewmodel

StudentFragment :Fragment(){

private val args: StudentFragmentArgs by navArgs()
private var viewModel:ViewModel?=null
override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    viewModel = ViewModelProvider(this).get(MainModleView.class)
    vviewModel.inputName.value =  args.Student
 }
}