LiveData.value returns Null But Livedata Direct Observe it getting result

Question

When I want to set live-data to mutable live data I call live data.getvalue() but it returns null

private const val TAG = "MainViewModel"

@HiltViewModel class MainViewModel @Inject constructor(private val repository: VaultRepository) : ViewModel() { private var dashMutableData = MutableLiveData<List>() var dashLiveData: LiveData<List> = dashMutableData

init {
    Log.d(TAG, " Init Executed ")
    viewModelScope.launch(Dispatchers.Default) {
        var liveData: LiveData<List<CategoriesModel>> = repository.getDashBoardData()
        Log.d(TAG, "${liveData.value}")
        dashMutableData.postValue(liveData.value)
    }
}

}

Can you show code of Activity/Fragment where you observe your LiveData and code of `MainViewModel`? — Dương Minh, Oct 19 '21 at 09:07
viewModel.dashLiveData.observe(this, Observer{ it?.let { Log.d(TAG, "LiveData: ${it.toString()}") } }) — Vamsi Reddy, Oct 19 '21 at 09:21
Please do not use images to show your code. Use a code snippet or use markdown to display your code. It makes it easier for others to debug your code and makes your questions easier to answer. — Dương Minh, Oct 19 '21 at 09:28

Torkel Velure · Answer 1 · 2021-10-19T13:24:14.837

Why return LiveData from your repository if you are not going to observe it? You could just return List<CategoriesModel> from your repository.

LiveData does not have a value unless it has an observer. If you add an observer, it will get a value once the observer has triggered once.

You shouldn't do this, but just to prove the point, if you add an observer before accessing the value it should work:

init {
    Log.d(TAG, " Init Executed ")
    viewModelScope.launch(Dispatchers.Default) {
        var liveData: LiveData<List<CategoriesModel>> = repository.getDashBoardData()
        livedata.observeForever(object: Observer<T> {
            override fun onChanged(value: T) {
                removeObserver(this)
            }
        })
        delay(100) //not sure this is needed, just making sure the observer triggered once.
        dashMutableData.postValue(liveData.value)
        Log.d(TAG, "${liveData.value}")
    }
}

In Viewmodel we cant get content how can we pass content in observeForever — Vamsi Reddy, Oct 19 '21 at 13:19

LiveData.value returns Null But Livedata Direct Observe it getting result

1 Answers1