👀 Views: 53 💬 Answers: 1 📅 Created: 2025-06-13

android livedata viewmodel navigation-component kotlin

I'm a bit lost with Quick question that's been bugging me - I'm encountering a frustrating issue where my LiveData in a ViewModel does not seem to trigger the UI update when navigating between fragments in my Android app using the Navigation Component....... I'm currently using AndroidX libraries, particularly version `2.3.5` for Navigation and `2.2.0` for Lifecycle. My setup involves a ViewModel that fetches data from a repository and exposes it as LiveData. Here's a simplified version of my ViewModel: ```kotlin class MyViewModel(application: Application) : AndroidViewModel(application) { private val repository: MyRepository = MyRepository() val data: LiveData<List<Item>> = repository.getData() } ``` The repository method looks like this: ```kotlin class MyRepository { fun getData(): LiveData<List<Item>> { val data = MutableLiveData<List<Item>>() // Simulate fetching data data.postValue(listOf(Item("Item 1"), Item("Item 2"))) return data } } ``` In my fragment, I observe the LiveData like this: ```kotlin class MyFragment : Fragment() { private lateinit var viewModel: MyViewModel override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? { val view = inflater.inflate(R.layout.fragment_my, container, false) viewModel = ViewModelProvider(this).get(MyViewModel::class.java) viewModel.data.observe(viewLifecycleOwner, Observer { items -> // Update UI }) return view } } ``` The problem arises when I navigate away from this fragment and then back to it. The `observe` block does not get triggered again, and I do not see updated data. The only way I can get the UI to update is to manually call `viewModel.data.value` or recreate the ViewModel, which feels like a hack. I've verified that the LiveData is indeed changing by logging its value in the repository. I also ensured that I am using the correct `viewLifecycleOwner` in the fragment. Am I missing something about how LiveData works with the Navigation Component? Any guidance on ensuring my UI updates properly when navigating back to the fragment would be greatly appreciated! I'm working on a API that needs to handle this. What am I doing wrong? What's the best practice here? I'd really appreciate any guidance on this. Is this even possible?