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RecyclerView is not updated when an update occurs in Room

I have a RecyclerView where an item can be edited via a DialogFragment, so when an item is clicked a Dialog is shown, then I can change some properties of that item, the issue is that RecyclerView is not updated with the updated properties and I have to force a notifyItemChanged when the Dialog is closed.
When an item in RecyclerView is clicked I set a MutableLiveData in my ViewModel so then it can be manipulated in the Dialog.
My ViewModel looks like this:
#HiltViewModel
class DocumentProductsViewModel #Inject constructor(private val repository: DocumentProductsRepository) :
ViewModel() {
val barcode = MutableLiveData<String>()
private val _selectedProduct = MutableLiveData<DocumentProduct>()
val selectedProduct: LiveData<DocumentProduct> = _selectedProduct
private val _selectedDocumentId = MutableLiveData<Long>()
val selectedDocumentId: LiveData<Long> = _selectedDocumentId
val products: LiveData<List<DocumentProduct>> = _selectedDocumentId.switchMap { documentId ->
repository.getDocumentProducts(documentId).asLiveData()
}
fun insert(documentProduct: DocumentProduct) = viewModelScope.launch {
repository.insert(documentProduct)
}
fun setProductQuantity(quantity: Float) {
_selectedProduct.value = _selectedProduct.value.also {
it?.timestamp = System.currentTimeMillis()
it?.quantity = quantity
}
update()
}
fun start(documentId: Long?) = viewModelScope.launch{
if (documentId == null) {
_selectedDocumentId.value = repository.getHeaderByType("Etichette")?.id
}
documentId?.let { documentId ->
_selectedDocumentId.value = documentId
}
}
fun select(product: DocumentProduct) {
_selectedProduct.value = product
}
fun delete() = viewModelScope.launch {
_selectedProduct.value?.let { repository.delete(it) }
}
private fun update() = viewModelScope.launch {
_selectedProduct.value?.let { repository.update(it) }
}
}
And in my fragment I'm subscribed to products as this:
private fun initRecyclerView() {
binding.rvProducts.adapter = adapter
viewModel.products.observe(viewLifecycleOwner) { products ->
val productsCount = products.count()
binding.tvProductsCount.text =
resources.getQuantityString(R.plurals.articoli, productsCount, productsCount)
// TODO: create amount string and set it with resources
binding.tvProductsAmount.text = productsCount.toEuro()
adapter.submitList(products)
binding.rvProducts.smoothScrollToPosition(adapter.itemCount - 1)
}
initSwipe(adapter)
}
When setProductQuantity is called the RecyclerView remains unchanged until notify is called while delete works fine without the necessity of calling any notify on RecyclerView.
UPDATE:
The item position is actually changed in RecyclerView as it's sorted by it's last changed timestamp BUT not the quantity field.
Here is my Adapter:
class DocumentProductsListAdapter : ListAdapter<DocumentProduct, DocumentProductsListAdapter.ViewHolder>(ProductDiffCallback) {
override fun onCreateViewHolder(viewGroup: ViewGroup, viewType: Int): ViewHolder {
val view: View = LayoutInflater.from(viewGroup.context)
.inflate(R.layout.layout_item, viewGroup, false)
return ViewHolder(view)
}
override fun onBindViewHolder(holder: ViewHolder, position: Int) {
val product = getItem(position)
holder.bind(product)
}
class ViewHolder(view: View) : RecyclerView.ViewHolder(view) {
val barcode: TextView = itemView.findViewById(R.id.barcode)
val quantity: TextView = itemView.findViewById(R.id.quantity)
val description: TextView = itemView.findViewById(R.id.description)
val unitOfMeasure: TextView = itemView.findViewById(R.id.unitOfMeasure)
fun bind(product: DocumentProduct) {
barcode.text = product.barcode
quantity.text = product.quantity.formatForQta().replace(".", ",")
if (product.labelType != null && product.labelType != "") {
unitOfMeasure.text = product.labelType
} else {
unitOfMeasure.text = product.unitOfMeasure?.lowercase(Locale.ITALIAN)
}
description.text = product.description ?: "-"
}
}
}
object ProductDiffCallback : DiffUtil.ItemCallback<DocumentProduct>() {
override fun areItemsTheSame(oldItem: DocumentProduct, newItem: DocumentProduct): Boolean {
return oldItem.id == newItem.id
}
override fun areContentsTheSame(oldItem: DocumentProduct, newItem: DocumentProduct): Boolean {
return oldItem == newItem
}
}
data class DocumentProduct(
#PrimaryKey(autoGenerate = true)
var id: Long,
var barcode: String,
#Json(name = "desc")
var description: String?,
#ColumnInfo(defaultValue = "PZ")
#Json(name = "um")
var unitOfMeasure: String?,
#Json(name = "qta")
var quantity: Float,
#Json(name = "id_testata")
var documentId: Long,
#Json(name = "tipo_frontalino")
var labelType: String?,
var timestamp: Long?
) {
constructor(barcode: String, documentId: Long, labelType: String?) : this(
0,
barcode,
null,
"PZ",
1f,
documentId,
labelType,
null
)
override fun equals(other: Any?): Boolean {
return super.equals(other)
}
override fun hashCode(): Int {
return super.hashCode()
}
}

You have the implementations of areContentsTheSame() and areItemsTheSame() swapped.
areContentsTheSame() is asking if everything in the two items being compared is the same. Therefore, if the class has a proper equals()/hashcode() for all properties used by the ViewHolder, you can use oldItem == newItem. If you use a data class with all relevant properties in the primary constructor, then you don't need to manually override equals()/hashcode().
areItemsTheSame() is asking if the two items represent the same conceptual row item, with possible differences in their details. So it should be oldItem.id == newItem.id.
The problem with your data class is that you are overriding equals()/hashcode() without providing any implementation at all. This is effectively disabling the proper implementations that are provided by the data modifier by calling through to the super implementation in the Any class. You should not override them at all when you use data class.

LiveData change not observed when Item data changes in the List

I am trying to observe Item data changes in a List using LiveData. But for some reason it is not working as expected.
ViewModel
#HiltViewModel
class TestScreenViewModel #Inject constructor(private val repository: TestRepository) :
ViewModel() {
val _orderItems: LiveData<List<OrderItem>> = repository.getAllTestOrder().asLiveData()
val orderItems: LiveData<List<OrderItem>> = _orderItems
fun addOrderItem() {
val item = OrderItem(name = "Order 1", price = 50, qty = 2)
viewModelScope.launch {
repository.addOrder(item)
}
}
fun deleteAll() = viewModelScope.launch { repository.deleteAll() }
fun changeValueOfItem() {
_orderItems.value!![0].addQty()
}
}
OrderItem
#Entity(tableName = "orders")
data class OrderItem constructor(
#PrimaryKey(autoGenerate = true)
#NonNull
val id: Int=0,
var name: String = "",
var price: Int = 0,
var imageUrl: String = "",
var qty: Int = 0
) {
fun addQty() {
qty++
}
fun removeQty() {
qty--
}
fun updateQty(q: Int) {
qty = q
}
}
During fun changeValueOfItem() call I just updated the qty by 1.
I already have a observable for orderItems in my Fragment but the changes are not detected.
What I am doing wrong here? Or Is there any other way to implement this scenario?

Faced similar behavior some time ago.
For it to work properly you need to actually return LiveData from your database like this:
//your DAO
#Query(select * from smth)
fun getAllTestOrder(): LiveData<List<OrderItems>>
And also remove .asLiveData() in your ViewModel and instead do something like this
val _orderItems = repository.getAllTestOrder()
val orderItems: LiveData<List<OrderItem>> = _orderItems

How to get an id of an added object from an Activity(VIEW) in a database(MODEL) through VIEWMODEL | Android, MVVM

I have a ShoppingList App that is built on MVVM architecture Android.
I did not make it, but I followed a tutorial on Youtube.
This is the image of the app(1/2) where the shopping list is shown. The bottom right side is a button for adding new elements of the list.
This is the second view(2/2) where the dialog appears to enter a name of our element and amount of it. Here we have cancel button and add button.
The problem is when I click the ADD button on the Dialog Box I do not know how to get an ID of this added item to the recycler view on my VIEW and to make it appear via the TOAST command on my main Activity.
The question is - How to get an ID of a new added element to my shopping list and show it on my MainActivity(ShoppingActivity) VIEW when I click the ADD button?
If you need additional information ask me out immediately! I will provide you anything you need.
Code is provided here:
ShoppingActivity(View)
class ShoppingActivity : AppCompatActivity(), KodeinAware {
override val kodein by kodein()
private val factory: ShoppingViewModelFactory by instance()
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_shopping)
// View Model is being created out of other classes to set changes to View
val viewModel = ViewModelProviders.of(this, factory).get(ShoppingViewModel::class.java)
// Adapters and Recycler View
val adapter = ShoppingItemAdapter(listOf(), viewModel)
rvShoppingItems.layoutManager = LinearLayoutManager(this)
rvShoppingItems.adapter = adapter
// ViewModel makes changes to the Activity
viewModel.getAllShoppingItems().observe(this, Observer {
adapter.items = it
adapter.notifyDataSetChanged()
})
fab.setOnClickListener {
AddShoppingItemDialog(this ,
object: AddDialogListener{
override fun onAddButtonClicked(item: ShoppingItem) {
viewModel.upsert(item)
showToast(viewModel.getID(item).toString().toInt())
}
}).show()
}
}
fun showToast(id: Int) {
Toast.makeText(this#ShoppingActivity, "ID записи: $id", Toast.LENGTH_LONG).show()
}}
ShoppingViewModel(ViewModel)
class ShoppingViewModel(private val repository: ShoppingRepository): ViewModel() {
fun upsert(item: ShoppingItem) = CoroutineScope(Dispatchers.IO).launch {
repository.upsert(item)
}
fun delete(item: ShoppingItem) = CoroutineScope(Dispatchers.IO).launch {
repository.delete( item)
}
fun getID(item: ShoppingItem) = repository.getID(item)
fun getAllShoppingItems() = repository.getAllShoppingItems()
}
AddShoppingItemDialog(the logic of showing Dialog info)
class AddShoppingItemDialog(context: Context, var addDialogListener: AddDialogListener): AppCompatDialog(context) {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.dialog_add_shopping_item)
tvAdd.setOnClickListener {
val name = etName.text.toString()
val amount = etAmount.text.toString()
if(name.isEmpty()) {
Toast.makeText(context, "Please enter the name", Toast.LENGTH_LONG).show()
return#setOnClickListener
}
if(amount.isEmpty()) {
Toast.makeText(context, "Please enter the amount", Toast.LENGTH_LONG).show()
return#setOnClickListener
}
val item = ShoppingItem(name, amount.toInt())
// We need to
addDialogListener.onAddButtonClicked(item)
dismiss()
}
tvCancel.setOnClickListener {
cancel()
}
}}
Repository
class ShoppingRepository(private val db: ShoppingDatabase) {
suspend fun upsert(item: ShoppingItem) = db.getShoppingDao().upsert(item)
suspend fun delete(item: ShoppingItem) = db.getShoppingDao().delete(item)
fun getID(item: ShoppingItem) = db.getShoppingDao().getID(item)
fun getAllShoppingItems() = db.getShoppingDao().getAllShoppingItems()}
ShoppingDAO
#Dao
interface ShoppingDao {
#Insert(onConflict = OnConflictStrategy.REPLACE)
suspend fun upsert(item: ShoppingItem) : Long
#Delete
suspend fun delete(item: ShoppingItem)
#Query("SELECT * FROM shopping_items WHERE id = $CURRENT_POSITION")
fun getID(item: ShoppingItem): LiveData<Int>
#Query("SELECT * FROM shopping_items")
fun getAllShoppingItems(): LiveData<List<ShoppingItem>>
}
ShoppingItem
const val CURRENT_POSITION = 0
#Entity(tableName = "shopping_items")
data class ShoppingItem(
#ColumnInfo(name = "item_name")
var name: String,
#ColumnInfo(name = "item_amount")
var amount: Int
) {
#PrimaryKey(autoGenerate = true)
var id: Int? = CURRENT_POSITION
}
AddDialogListener
interface AddDialogListener {
fun onAddButtonClicked(item: ShoppingItem)
}
App View with added items

Since insert/upsert operations on Database are suspend functions, observe returned id in view model
In ShoppingViewModel
private var _itemId : Long = MutableLiveData<Long>()
val itemId : LiveData<Long>
get() = _itemId
fun upsert(item: ShoppingItem) = CoroutineScope(Dispatchers.IO).launch {
val id = repository.upsert(item)
_itemId.postValue(id)
}
In ShoppingActivity,
viewModel.itemId.observe(this, Observer {id ->
showToast(id)
})
Please let me know if you need to know more details.

You need to use SingleLiveEvent to observe the value only once.
Add this SingleLiveEvent class
/**
* A lifecycle-aware observable that sends only new updates after subscription, used for events like
* navigation and Snackbar messages.
*
*
* This avoids a common problem with events: on configuration change (like rotation) an update
* can be emitted if the observer is active. This LiveData only calls the observable if there's an
* explicit call to setValue() or call().
*
*
* Note that only one observer is going to be notified of changes.
*/
class SingleLiveEvent<T> : MutableLiveData<T>() {
private val mPending = AtomicBoolean(false)
#MainThread
override fun observe(owner: LifecycleOwner, observer: Observer<in T>) {
if (hasActiveObservers()) {
Log.w(TAG, "Multiple observers registered but only one will be notified of changes.")
}
// Observe the internal MutableLiveData
super.observe(owner, Observer { t ->
if (mPending.compareAndSet(true, false)) {
observer.onChanged(t)
}
})
}
#MainThread
override fun setValue(t: T?) {
mPending.set(true)
super.setValue(t)
}
/**
* Used for cases where T is Void, to make calls cleaner.
*/
#MainThread
fun call() {
value = null
}
companion object {
private val TAG = "SingleLiveEvent"
}
}
In ShoppingViewModel
Replace this
private var _itemId : Long = MutableLiveData<Long>()
val itemId : LiveData<Long>
get() = _itemId
with
private var _itemId : Long = SingleLiveEvent<Long>()
val itemId : LiveData<Long>
get() = _itemId
You can use Event wrapper when there are more than one observer.
For more details:
https://medium.com/androiddevelopers/livedata-with-snackbar-navigation-and-other-events-the-singleliveevent-case-ac2622673150

Android MVVM + Room creating LiveData RecyclerViewItem objects by other LiveData objects

I have Room Entity Class "Symptom" with name of Symptom and id of it.
#Entity(tableName = "symptoms")
data class Symptom(
#PrimaryKey #NonNull val id: Int,
val name: String) {
override fun toString(): String {
return "Symptom $id: $name"
}
}
I'm getting it in the following classses:
SymptomDao
#Dao
interface SymptomDao {
#Query("SELECT * FROM symptoms WHERE id=:id LIMIT 1")
fun getSymptom(id: Int): Symptom
#Query("SELECT * FROM symptoms")
fun getAllSymptoms(): LiveData<List<Symptom>>
}
SymptomRepository
class SymptomRepository(private val symptomDao: SymptomDao) {
fun getSymptom(id: Int) = symptomDao.getSymptom(id)
fun getAllSymptoms() = symptomDao.getAllSymptoms()
}
SymptomsViewModel
class SymptomsViewModel(symptomRepository: SymptomRepository): ViewModel() {
private val symptomsList = symptomRepository.getAllSymptoms()
private val symptomsItemsList: MutableLiveData<List<SymptomItem>> = MutableLiveData()
fun getAllSymptoms(): LiveData<List<Symptom>> {
return symptomsList
}
fun getAllSymptomsItems(): LiveData<List<SymptomItem>> {
return symptomsItemsList
}
}
I have RecyclerView with list of SymptomItem with Checkboxes to remember which Symptoms of a list users chooses:
data class SymptomItem(
val symptom: Symptom,
var checked: Boolean = false)
Question
My question is how can I get LiveData<List<SymptomItem>> by LiveData<List<Symptom>>? I have just started learning MVVM and I can't find a simply answer how to do that. I have already tried to fill this list in various ways, but It loses checked variable every time I rotate my phone. I'll be grateful for any hints.

You'll need to store which items are checked by storing their Ids in a List within the ViewModel. Then you'll have combine the list of your Symptom objects and the list of which items are checked, and generate the list of SymptomItem objects.
I'm going to use Kotlin Flow to achieve this.
#Dao
interface SymptomDao {
#Query("SELECT * FROM symptoms")
fun flowAllSymptoms(): Flow<List<Symptom>>
}
class SymptomRepository(private val symptomDao: SymptomDao) {
fun flowAllSymptoms() = symptomDao.flowAllSymptoms()
}
class SymptomsViewModel(
private val symptomRepository: SymptomRepository
) : ViewModel() {
private val symptomsListFlow = symptomRepository.flowAllSymptoms()
private val symptomsItemsList: MutableLiveData<List<SymptomItem>> = MutableLiveData()
private var checkedIdsFlow = MutableStateFlow(emptyList<Int>())
init {
viewModelScope.launch {
collectSymptomsItems()
}
}
private suspend fun collectSymptomsItems() =
flowSymptomsItems().collect { symptomsItems ->
symptomsItemsList.postValue(symptomsItems)
}
private fun flowSymptomsItems() =
symptomsListFlow
.combine(checkedIdsFlow) { list, checkedIds ->
list.map { SymptomItem(it, checkedIds.contains(it.id)) }
}
fun checkItem(id: Int) {
(checkedIdsFlow.value as MutableList<Int>).add(id)
checkedIdsFlow.value = checkedIdsFlow.value
}
fun uncheckItem(id: Int) {
(checkedIdsFlow.value as MutableList<Int>).remove(id)
checkedIdsFlow.value = checkedIdsFlow.value
}
fun getSymptomsItems(): LiveData<List<SymptomItem>> {
return symptomsItemsList
}
}
In your Fragment, observe getSymptomsItems() and update your adapter data.
The code is not tested, you may have to make small adjustments to make it compile.

Room SQLite query doesn't return any results, even though there are rows in the database that match

I am using this command to get data from a Room database:
select * from location_search_results where searchQuery = "wilmington"
Here is what the database looks like:
And here are the search results:
I have verified that the name of the table is correct and everything, and there's no spelling errors that I can find, so why would this query not return any of the three rows that it should match?
EDIT for code:
The source code is publicly available here, I am working in the mvvm branch, so if you pull it, make sure you're there. Below are the relevant classes:
LocationSearchResponse.kt:
#Entity(tableName = "location_search_results")
class LocationSearchResponse(
#ColumnInfo(name = "type")
val type: String,
#TypeConverters(DataConverter::class)
#SerializedName("query")
val searchQuery: List<String>,
#TypeConverters(DataConverter::class)
val features: List<Feature>,
#ColumnInfo(name = "attribution")
val attribution: String
) {
#PrimaryKey(autoGenerate = true)
var id: Int = 0
}
LocationSearchRepositoryImpl.kt:
class LocationSearchRepositoryImpl (
private val locationResponseDao: LocationResponseDao,
private val locationNetworkDataSource: LocationNetworkDataSource
): LocationSearchRepository {
init {
locationNetworkDataSource.downloadedLocationSearchResults.observeForever { locationResults ->
persistFetchedLocations(locationResults)
}
}
// update search data in db if necessary, then return the data that was searched for.
override suspend fun searchForLocation(query: String): LiveData<out LocationSearchResponse> {
return withContext(Dispatchers.IO) {
initSearch(query)
return#withContext locationResponseDao.searchForLocation(query)
}
}
// if a fetch is necessary (query has not already been searched), fetch search results
private suspend fun initSearch(query: String) {
if (isFetchLocationResultsNeeded(query))
fetchLocationResults(query)
}
private fun isFetchLocationResultsNeeded(query: String) : Boolean {
// get the cached results. If it's null, return true because it needs to be updated
val cachedResults = locationResponseDao.searchForLocationNonLive(query.toLowerCase())
if (cachedResults == null) return true
// if the results are empty, it needs to be fetched, else it doesn't
return cachedResults.features.isEmpty()
}
private suspend fun fetchLocationResults(query: String) {
locationNetworkDataSource.fetchLocationSearchResults("mapbox.places", query)
}
private fun persistFetchedLocations(fetchedLocationResults: LocationSearchResponse) {
GlobalScope.launch(Dispatchers.IO) {
locationResponseDao.upsert(fetchedLocationResults)
}
}
}
LocationResponseDao.kt:
#Dao
interface LocationResponseDao {
// update or insert existing entry if there is a conflict when adding to db
#Insert(onConflict = OnConflictStrategy.REPLACE)
fun upsert(locationResults: LocationSearchResponse)
#Query("select * from location_search_results WHERE searchQuery = :query")
fun searchForLocation(query: String): LiveData<LocationSearchResponse>
#Query("select * from location_search_results WHERE searchQuery = :query")
fun searchForLocationNonLive(query: String): LocationSearchResponse?
#Query("delete from location_search_results")
fun nukeTable()
}
and ChooseCityFragment.kt:
class ChooseCityFragment : ScopedFragment(), KodeinAware {
override val kodein by closestKodein()
private val locationViewModelFactory: LocationResponseViewModelFactory by instance()
private val weatherResponseViewModelFactory: WeatherResponseViewModelFactory by instance()
private lateinit var locationViewModel: LocationResponseViewModel
private lateinit var weatherViewModel: WeatherResponseViewModel
override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?): View? {
setupViews()
// Inflate the layout for this fragment
return inflater.inflate(R.layout.choose_city_fragment, container, false)
}
override fun onActivityCreated(savedInstanceState: Bundle?) {
super.onActivityCreated(savedInstanceState)
locationViewModel = ViewModelProviders.of(this, locationViewModelFactory)
.get(LocationResponseViewModel::class.java)
weatherViewModel = ViewModelProviders.of(this, weatherResponseViewModelFactory)
.get(WeatherResponseViewModel::class.java)
updateToolbar()
}
fun updateToolbar() {
(activity as? AppCompatActivity)?.supportActionBar?.title = "Choose Location"
(activity as? AppCompatActivity)?.supportActionBar?.subtitle = null
}
fun bindUI() = launch {
val locationResults = locationViewModel.locationResponse
val owner = viewLifecycleOwner
locationResults.observe(owner, Observer {
if (it == null) return#Observer
// TODO: set loading icon to GONE
initRecyclerView(it.features.toLocationSearchResultListItem())
})
}
fun setupViews() = launch {
search_button.setOnClickListener {
searchLocations()
search_results_rv.adapter?.notifyDataSetChanged()
}
}
// TODO: search text can not be more than 20 words or more than 256 characters. Need to account for this
fun searchLocations() = launch {
val searchText = search_box.text.toString()
if (searchText != "") {
locationViewModel.searchLocation(search_box.text.toString())
bindUI()
} else
Toast.makeText(context?.applicationContext, "Please enter a search term", Toast.LENGTH_SHORT).show()
}
private fun List<Feature>.toLocationSearchResultListItem() : List<LocationSearchResultListItem> {
return this.map {
LocationSearchResultListItem(it)
}
}
private fun initRecyclerView(items: List<LocationSearchResultListItem>) {
val groupAdapter = GroupAdapter<ViewHolder>().apply {
addAll(items)
}
groupAdapter.notifyDataSetChanged()
search_results_rv.apply {
layoutManager = LinearLayoutManager(this#ChooseCityFragment.context)
adapter = groupAdapter
}
groupAdapter.setOnItemClickListener { item, view ->
(item as? LocationSearchResultListItem)?.let {
refreshWeather(it.feature.coordinates[0], it.feature.coordinates[1])
}
}
}
private fun refreshWeather(latitude: Double, longitude: Double) = launch {
weatherViewModel.refreshWeatherWithCoordinates(latitude, longitude)
}
}

It turns out there was a space being added to the end of the searchQuery that I wasn't able to see. Once I figured out where my code was adding that space, I removed it and now everything looks good.

try something like this
it`s a dao interface example
use big letters in your query
#Query("SELECT * FROM person WHERE favoriteColor LIKE :color")
List<Person> getAllPeopleWithFavoriteColor(String color);
more info here