Live Data observe for object single property change

user_8795199 0
Viewed 2155

In Android project implemented Android Architecture component successfully as per developer guideline but the problem is we can observe full object change using LiveData 

  mQueViewModel.getLiveQuestion().observe(this, new Observer<Question>() {
        @Override
        public void onChanged(@Nullable Question question) {
            Log.i(TAG, "onChanged: ");
            setQuestionDetails();
        }
    });

Any single object property change fire OnChanged this cause to set all data again to UI So is there any way to implement property change like onDescriptionChange, onImageChange ...

android-architecture-components mvvm android
2 Answers

To do that you could use the ViewModel to break the data in smaller pieces. Something like this should work:

private LiveData<Question> questions;
private MediatorLiveData<String> description;

public MQueViewModel() {

    description = new MediatorLiveData<>();
    description.addSource(questions, new Observer<Question>() {
        @Override
        public void onChanged(@Nullable Question question) {
            if (question == null) return;
            if (!question.description.equals(description.getValue())) {
                description.setValue(question.description);
            }
        }
    });

}

and have than have your UI subscribe to description. Add similar MediatorLiveData to any other property change u need.

user_9063620

may be its so late but you can have two option

1- implementing Property “Aware” MutableLiveData as described here

2- whenever the property changed set the value to itself 

 private  var _currentPacket = MutableLiveData<PacketEntity>()
 fun test() {
     _currentPacket.value!!.someproperty= somevalue 
     _currentPacket.value=_currentPacket.value 
  }
user_32915200
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