How to databind livedata object (android)

Question

Today I've some question about mvvm and databinding on android,

I'm trying to bind object properties on view.

I've an Object (Model) with some properties, by example :

public String name;
public String title;
public int value;

I've a ViewModel with livedata like this :

MutableLiveData<Object> _obj = new MutableLiveData<>();
public LiveData<Object> obj = _obj;

And, at last, I've a view like this :

<layout>
    <data>
        <variable
            name="viewModel">
            type="com.sample.app.viewmodels.MainViewModel" />
    </data>
    <LinearLayout
        ... >
        <TextView
            android:text:="@{viewModel.obj.name}"
            .../>
    </LinearLayout>
</layout>

I saw that we can do that in a video from "Android Developers" about "LiveData" : https://youtu.be/OMcDk2_4LSk?t=102

She says that its possible in Android studio on 3.1+ versions. But this is not working for me.

Have you set the ViewModel in your Activity/Fragment binding? Check this [link](https://developer.android.com/topic/libraries/data-binding/architecture) — Sanlok Lee, Jul 05 '19 at 20:17
do you also set `binding.viewModel = viewModel`? Can you show the pare where you set these binding parameters — Sanlok Lee, Jul 05 '19 at 20:59
Yes, I do this : `public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) { MainViewModel viewModel = ViewModelProviders.of(this).get(MainViewModel.class); MainFragmentBinding binding = MainFragmentBinding.inflate(getLayoutInflater()); binding.setViewModel(viewModel); binding.setLifecycleOwner(this); return binding.getRoot(); }` — C. MARTIN, Jul 05 '19 at 21:14
why you create a ```livedata``` from your ```MuteableLiveData```? why donsn't use the ```MuteableLiveData``` for binding? — mahdi shahbazi, Jul 06 '19 at 06:11
Yes it's olso possible, and at the first time it was the case, but it's the same result. — C. MARTIN, Jul 06 '19 at 08:13
Finally its working ! but the object fields are not provided by Android Studio. I do this manualy. Another thing does not work, the ui update, when I change a value in field I do a calculation and I'd like to update my textview when the values changes. — C. MARTIN, Jul 06 '19 at 15:35

score 2 · Accepted Answer · answered Jul 21 '19 at 16:21

For this to work, your model class must extend BaseObservable class from databinding library. And you have to call notifyChange() on each setter method like this:

public class Object extends BaseObservable {
    public String name;
    public String title;
    public int value;

    public void setName(String name) {
        this.name = name;
        notifyChange();
    }

    public void setTitle(String title) {
        this.title = title;
        notifyChange();
    }

    public void setValue(int value) {
        this.value = value;
        notifyChange();
    }
}

Welcomw... please do upvote my answer if it helped you. :) – Birju Vachhani Jul 22 '19 at 12:58 — Birju Vachhani, Jul 22 '19 at 12:58

How to databind livedata object (android)

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