Final Results
Your todo_roster
layout resource should resemble:
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".ui.MainActivity">
<ProgressBar
android:id="@+id/loading"
style="?android:attr/progressBarStyle"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<TextView
android:id="@+id/empty"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/msg_empty"
android:textAppearance="?android:attr/textAppearanceMedium"
android:visibility="gone"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<androidx.recyclerview.widget.RecyclerView
android:id="@+id/items"
android:layout_width="0dp"
android:layout_height="0dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>
The modified RosterMotor
should look like:
package com.commonsware.todo.ui.roster
import androidx.lifecycle.ViewModel
import androidx.lifecycle.viewModelScope
import com.commonsware.todo.repo.ToDoModel
import com.commonsware.todo.repo.ToDoRepository
import kotlinx.coroutines.flow.SharingStarted
import kotlinx.coroutines.flow.map
import kotlinx.coroutines.flow.stateIn
import kotlinx.coroutines.launch
data class RosterViewState(
val items: List<ToDoModel> = listOf(),
val isLoaded: Boolean = false
)
class RosterMotor(private val repo: ToDoRepository) : ViewModel() {
val states = repo.items()
.map { RosterViewState(it, true) }
.stateIn(viewModelScope, SharingStarted.Eagerly, RosterViewState())
fun save(model: ToDoModel) {
viewModelScope.launch {
repo.save(model)
}
}
}
And the tweaked RosterListFragment
should look like:
package com.commonsware.todo.ui.roster
import android.os.Bundle
import android.view.*
import androidx.fragment.app.Fragment
import androidx.lifecycle.lifecycleScope
import androidx.navigation.fragment.findNavController
import androidx.recyclerview.widget.DividerItemDecoration
import androidx.recyclerview.widget.LinearLayoutManager
import com.commonsware.todo.R
import com.commonsware.todo.databinding.TodoRosterBinding
import com.commonsware.todo.repo.ToDoModel
import kotlinx.coroutines.flow.collect
import org.koin.androidx.viewmodel.ext.android.viewModel
class RosterListFragment : Fragment() {
private val motor: RosterMotor by viewModel()
private var binding: TodoRosterBinding? = null
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setHasOptionsMenu(true)
}
override fun onCreateView(
inflater: LayoutInflater,
container: ViewGroup?,
savedInstanceState: Bundle?
): View = TodoRosterBinding.inflate(inflater, container, false)
.also { binding = it }
.root
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
val adapter = RosterAdapter(
layoutInflater,
onCheckboxToggle = { motor.save(it.copy(isCompleted = !it.isCompleted)) },
onRowClick = ::display
)
binding?.items?.apply {
setAdapter(adapter)
layoutManager = LinearLayoutManager(context)
addItemDecoration(
DividerItemDecoration(
activity,
DividerItemDecoration.VERTICAL
)
)
}
viewLifecycleOwner.lifecycleScope.launchWhenStarted {
motor.states.collect { state ->
adapter.submitList(state.items)
binding?.apply {
loading.visibility = if (state.isLoaded) View.GONE else View.VISIBLE
when {
state.items.isEmpty() && state.isLoaded -> {
empty.visibility = View.VISIBLE
empty.setText(R.string.msg_empty)
}
else -> empty.visibility = View.GONE
}
}
}
}
}
override fun onDestroyView() {
binding = null
super.onDestroyView()
}
override fun onCreateOptionsMenu(menu: Menu, inflater: MenuInflater) {
inflater.inflate(R.menu.actions_roster, menu)
super.onCreateOptionsMenu(menu, inflater)
}
override fun onOptionsItemSelected(item: MenuItem): Boolean {
when (item.itemId) {
R.id.add -> {
add()
return true
}
}
return super.onOptionsItemSelected(item)
}
private fun display(model: ToDoModel) {
findNavController()
.navigate(RosterListFragmentDirections.displayModel(model.id))
}
private fun add() {
findNavController().navigate(RosterListFragmentDirections.createModel(null))
}
}
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