Update Navigation to 2.2.0 and add SavedStateHandle (#574)

* Update Navigation to 2.2.0 and add SavedStateHandle Persist values in PlantListViewModel using SavedStateHandle * Fix lint error
android · Feb 3, 2020 · c6c1379 · c6c1379
1 parent 2da1ffa
commit c6c1379
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Showing 5 changed files with 35 additions and 17 deletions.
diff --git a/app/src/main/java/com/google/samples/apps/sunflower/PlantListFragment.kt b/app/src/main/java/com/google/samples/apps/sunflower/PlantListFragment.kt
@@ -34,7 +34,7 @@ import com.google.samples.apps.sunflower.viewmodels.PlantListViewModel
 class PlantListFragment : Fragment() {
 
     private val viewModel: PlantListViewModel by viewModels {
-        InjectorUtils.providePlantListViewModelFactory(requireContext())
+        InjectorUtils.providePlantListViewModelFactory(this)
     }
 
     override fun onCreateView(

diff --git a/app/src/main/java/com/google/samples/apps/sunflower/utilities/InjectorUtils.kt b/app/src/main/java/com/google/samples/apps/sunflower/utilities/InjectorUtils.kt
@@ -17,6 +17,7 @@
 package com.google.samples.apps.sunflower.utilities
 
 import android.content.Context
+import androidx.fragment.app.Fragment
 import com.google.samples.apps.sunflower.data.AppDatabase
 import com.google.samples.apps.sunflower.data.GardenPlantingRepository
 import com.google.samples.apps.sunflower.data.PlantRepository
@@ -46,9 +47,9 @@ object InjectorUtils {
         return GardenPlantingListViewModelFactory(repository)
     }
 
-    fun providePlantListViewModelFactory(context: Context): PlantListViewModelFactory {
-        val repository = getPlantRepository(context)
-        return PlantListViewModelFactory(repository)
+    fun providePlantListViewModelFactory(fragment: Fragment): PlantListViewModelFactory {
+        val repository = getPlantRepository(fragment.requireContext())
+        return PlantListViewModelFactory(repository, fragment)
     }
 
     fun providePlantDetailViewModelFactory(

diff --git a/app/src/main/java/com/google/samples/apps/sunflower/viewmodels/PlantListViewModel.kt b/app/src/main/java/com/google/samples/apps/sunflower/viewmodels/PlantListViewModel.kt
@@ -18,6 +18,7 @@ package com.google.samples.apps.sunflower.viewmodels
 
 import androidx.lifecycle.LiveData
 import androidx.lifecycle.MutableLiveData
+import androidx.lifecycle.SavedStateHandle
 import androidx.lifecycle.ViewModel
 import androidx.lifecycle.switchMap
 import com.google.samples.apps.sunflower.PlantListFragment
@@ -27,11 +28,12 @@ import com.google.samples.apps.sunflower.data.PlantRepository
 /**
  * The ViewModel for [PlantListFragment].
  */
-class PlantListViewModel internal constructor(plantRepository: PlantRepository) : ViewModel() {
+class PlantListViewModel internal constructor(
+    plantRepository: PlantRepository,
+    private val savedStateHandle: SavedStateHandle
+) : ViewModel() {
 
-    private val growZoneNumber = MutableLiveData<Int>(NO_GROW_ZONE)
-
-    val plants: LiveData<List<Plant>> = growZoneNumber.switchMap {
+    val plants: LiveData<List<Plant>> = getSavedGrowZoneNumber().switchMap {
         if (it == NO_GROW_ZONE) {
             plantRepository.getPlants()
         } else {
@@ -40,16 +42,21 @@ class PlantListViewModel internal constructor(plantRepository: PlantRepository)
     }
 
     fun setGrowZoneNumber(num: Int) {
-        growZoneNumber.value = num
+        savedStateHandle.set(GROW_ZONE_SAVED_STATE_KEY, num)
     }
 
     fun clearGrowZoneNumber() {
-        growZoneNumber.value = NO_GROW_ZONE
+        savedStateHandle.set(GROW_ZONE_SAVED_STATE_KEY, NO_GROW_ZONE)
     }
 
-    fun isFiltered() = growZoneNumber.value != NO_GROW_ZONE
+    fun isFiltered() = getSavedGrowZoneNumber().value != NO_GROW_ZONE
+
+    private fun getSavedGrowZoneNumber(): MutableLiveData<Int> {
+        return savedStateHandle.getLiveData<Int>(GROW_ZONE_SAVED_STATE_KEY, NO_GROW_ZONE)
+    }
 
     companion object {
         private const val NO_GROW_ZONE = -1
+        private const val GROW_ZONE_SAVED_STATE_KEY = "GROW_ZONE_SAVED_STATE_KEY"
     }
 }
diff --git a/app/src/main/java/com/google/samples/apps/sunflower/viewmodels/PlantListViewModelFactory.kt b/app/src/main/java/com/google/samples/apps/sunflower/viewmodels/PlantListViewModelFactory.kt
@@ -16,18 +16,28 @@
 
 package com.google.samples.apps.sunflower.viewmodels
 
+import android.os.Bundle
+import androidx.lifecycle.AbstractSavedStateViewModelFactory
+import androidx.lifecycle.SavedStateHandle
 import androidx.lifecycle.ViewModel
-import androidx.lifecycle.ViewModelProvider
-
+import androidx.savedstate.SavedStateRegistryOwner
 import com.google.samples.apps.sunflower.data.PlantRepository
 
 /**
  * Factory for creating a [PlantListViewModel] with a constructor that takes a [PlantRepository].
  */
 class PlantListViewModelFactory(
-    private val repository: PlantRepository
-) : ViewModelProvider.NewInstanceFactory() {
+    private val repository: PlantRepository,
+    owner: SavedStateRegistryOwner,
+    defaultArgs: Bundle? = null
+) : AbstractSavedStateViewModelFactory(owner, defaultArgs) {
 
     @Suppress("UNCHECKED_CAST")
-    override fun <T : ViewModel> create(modelClass: Class<T>) = PlantListViewModel(repository) as T
+    override fun <T : ViewModel?> create(
+        key: String,
+        modelClass: Class<T>,
+        handle: SavedStateHandle
+    ): T {
+        return PlantListViewModel(repository, handle) as T
+    }
 }
diff --git a/build.gradle b/build.gradle
@@ -38,7 +38,7 @@ buildscript {
         ktxVersion = '1.0.2'
         lifecycleVersion = '2.2.0-alpha01'
         materialVersion = '1.1.0-alpha09'
-        navigationVersion = '2.0.0'
+        navigationVersion = '2.2.0'
         recyclerViewVersion = '1.1.0-alpha05'
         roomVersion = '2.1.0'
         runnerVersion = '1.0.1'