IssueTracker

Component used: Fragment

Version used: 1.6.2

The issue #137122478 had requested a lint rule for enforcing the use of viewLifecycleOwner when observing a LiveData in Fragments. We then got the FragmentLiveDataObserve rule in android lint.

Should we enforce the same when observing Flows in Fragments as well and create a similar rule?

For example, if we have a ViewModel exposing a uiState: StateFlow<T>:

class LatestNewsViewModel(
    private val newsRepository: NewsRepository
) : ViewModel() {

    val uiState: StateFlow<LatestNewsUiState> = _uiState

    init { /* ... * } 
}

The corresponding Fragment should ideally use viewLifecycleOwner's scope instead of the Fragment's scope? i.e.:

class LatestNewsFragment {
  
   private val viewModel by viewModels<LatestNewsViewModel>()

   override fun onViewCreated(...) {
      /* ... **/

      // 💥 Lint should fail and expect viewLifecycleOwner.lifecycleScope
      lifecycleScope.launch {
          repeatOnLifecycle(Lifecycle.State.STARTED) {
              viewModel.uiState.collect { binding.view.setState(it) }
          }
      }
   }
}