Data Binding Issues with Nested RecyclerView in Android 14 Using ViewModel and LiveData
Hey everyone, I'm running into an issue that's driving me crazy. I'm integrating two systems and I'm upgrading from an older version and I'm writing unit tests and I'm encountering a frustrating issue with data binding in a nested RecyclerView setup while using ViewModel and LiveData in Android 14. I have a parent RecyclerView that displays a list of categories, and each category has its own child RecyclerView that lists items within that category. The child RecyclerViews are not updating their UI when the underlying LiveData changes, even though I can see the data is being updated in the ViewModel. Here’s a simplified version of my setup: **ViewModel:** ```kotlin class MyViewModel : ViewModel() { private val _categories = MutableLiveData<List<Category>>() val categories: LiveData<List<Category>> get() = _categories init { fetchCategories() } private fun fetchCategories() { // Simulated fetch from a data source _categories.value = listOf(Category("Fruits", listOf(Item("Apple"), Item("Banana"))), Category("Vegetables", listOf(Item("Carrot"), Item("Lettuce")))) } } ``` **Adapter for Parent RecyclerView:** ```kotlin class ParentAdapter(private val categories: List<Category>) : RecyclerView.Adapter<ParentAdapter.ParentViewHolder>() { override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ParentViewHolder { val view = LayoutInflater.from(parent.context).inflate(R.layout.item_parent, parent, false) return ParentViewHolder(view) } override fun onBindViewHolder(holder: ParentViewHolder, position: Int) { holder.bind(categories[position]) } override fun getItemCount() = categories.size class ParentViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView) { private val childRecyclerView: RecyclerView = itemView.findViewById(R.id.child_recycler_view) fun bind(category: Category) { // Setup child RecyclerView here... val childAdapter = ChildAdapter(category.items) childRecyclerView.adapter = childAdapter } } } ``` When I change the data in the ViewModel by calling `fetchCategories()` again (for instance, after a user action), the parent RecyclerView updates correctly, but the child RecyclerViews do not reflect the changes. I've ensured that the child adapter is being instantiated with the updated data, but it seems the child adapters are not notified of data changes. I've tried using `notifyDataSetChanged()` on the child adapters after updating the data, but that doesn't seem to solve the issue. I also verified that the LiveData is indeed emitting new values by observing it in the Fragment, which is set up like this: ```kotlin viewModel.categories.observe(viewLifecycleOwner, Observer { categories -> parentAdapter.updateCategories(categories) }) ``` I would greatly appreciate any insights into why the child RecyclerViews aren't updating as expected, or if there's a better approach to manage nested RecyclerViews with dynamic data in Android 14. Thanks for taking the time to read this! I'm on Debian using the latest version of Kotlin. Thanks for taking the time to read this! I'm coming from a different tech stack and learning Kotlin. I'd really appreciate any guidance on this.