Refactor retrieving ViewModels

mlykotom · mlykotom · commit 52a90c0d9a9f · 2025-07-07T15:00:19.000+02:00
diff --git a/Fruitties/androidApp/src/main/AndroidManifest.xml b/Fruitties/androidApp/src/main/AndroidManifest.xml
@@ -22,7 +22,7 @@
         android:dataExtractionRules="@xml/data_extraction_rules"
         android:supportsRtl="true"
         android:theme="@style/AppTheme"
-        android:name=".di.App">
+        android:name=".FruittiesAndroidApp">
         <activity
             android:name=".MainActivity"
             android:exported="true">
diff --git a/Fruitties/androidApp/src/main/java/com/example/fruitties/android/FruittiesAndroidApp.kt b/Fruitties/androidApp/src/main/java/com/example/fruitties/android/FruittiesAndroidApp.kt
@@ -14,13 +14,14 @@
  * limitations under the License.
  */
 
-package com.example.fruitties.android.di
+package com.example.fruitties.android
 
 import android.app.Application
+import androidx.compose.runtime.staticCompositionLocalOf
 import com.example.fruitties.di.AppContainer
 import com.example.fruitties.di.Factory
 
-class App : Application() {
+class FruittiesAndroidApp : Application() {
     /** AppContainer instance used by the rest of classes to obtain dependencies */
     lateinit var container: AppContainer
 
@@ -29,3 +30,11 @@ class App : Application() {
         container = AppContainer(Factory(this))
     }
 }
+
+/**
+ * Allows retrieving the AppContainer, which represents a DI graph everywhere from a composable.
+ * Because the [AppContainer] is effectively a singleton, we can use static composition local,
+ * because it won't change during the app execution.
+ */
+val LocalAppContainer =
+    staticCompositionLocalOf<AppContainer> { error("No AppContainer provided!") }
diff --git a/Fruitties/androidApp/src/main/java/com/example/fruitties/android/MainActivity.kt b/Fruitties/androidApp/src/main/java/com/example/fruitties/android/MainActivity.kt
@@ -24,6 +24,7 @@ import androidx.compose.foundation.layout.fillMaxSize
 import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.Surface
 import androidx.compose.runtime.Composable
+import androidx.compose.runtime.CompositionLocalProvider
 import androidx.compose.ui.Modifier
 import androidx.lifecycle.viewmodel.navigation3.rememberViewModelStoreNavEntryDecorator
 import androidx.navigation3.runtime.NavKey
@@ -36,6 +37,7 @@ import androidx.navigation3.ui.rememberSceneSetupNavEntryDecorator
 import com.example.fruitties.android.ui.CartScreen
 import com.example.fruitties.android.ui.FruittieScreen
 import com.example.fruitties.android.ui.ListScreen
+import com.example.fruitties.android.ui.FruittiesTheme
 import kotlinx.serialization.Serializable
 
 @Serializable
@@ -54,12 +56,16 @@ class MainActivity : ComponentActivity() {
         super.onCreate(savedInstanceState)
         enableEdgeToEdge()
         setContent {
-            MyApplicationTheme {
-                Surface(
-                    modifier = Modifier.fillMaxSize(),
-                    color = MaterialTheme.colorScheme.background,
-                ) {
-                    NavApp()
+            CompositionLocalProvider(
+                LocalAppContainer provides (this.applicationContext as FruittiesAndroidApp).container,
+            ) {
+                FruittiesTheme {
+                    Surface(
+                        modifier = Modifier.fillMaxSize(),
+                        color = MaterialTheme.colorScheme.background,
+                    ) {
+                        NavApp()
+                    }
                 }
             }
         }
diff --git a/Fruitties/androidApp/src/main/java/com/example/fruitties/android/ui/CartScreen.kt b/Fruitties/androidApp/src/main/java/com/example/fruitties/android/ui/CartScreen.kt
@@ -50,35 +50,23 @@ import androidx.compose.runtime.getValue
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.graphics.Color
-import androidx.compose.ui.platform.LocalContext
 import androidx.compose.ui.res.stringResource
 import androidx.compose.ui.text.style.TextAlign
 import androidx.compose.ui.tooling.preview.Preview
 import androidx.compose.ui.unit.dp
 import androidx.lifecycle.viewmodel.compose.viewModel
-import com.example.fruitties.android.MyApplicationTheme
 import com.example.fruitties.android.R
-import com.example.fruitties.android.di.App
+import com.example.fruitties.android.LocalAppContainer
 import com.example.fruitties.model.CartItemDetails
 import com.example.fruitties.model.Fruittie
 import com.example.fruitties.viewmodel.CartUiState
 import com.example.fruitties.viewmodel.CartViewModel
-import com.example.fruitties.viewmodel.creationExtras
 
 @Composable
-fun CartScreen(onNavBarBack: () -> Unit) {
-    // Instantiate a ViewModel with a dependency on the AppContainer.
-    // To make ViewModel compatible with KMP, the ViewModel factory must
-    // create an instance without referencing the Android Application.
-    // Here we put the KMP-compatible AppContainer into the extras
-    // so it can be passed to the ViewModel factory.
-    val app = LocalContext.current.applicationContext as App
-
-    val viewModel: CartViewModel = viewModel(
-        factory = CartViewModel.Factory,
-        extras = creationExtras(app.container),
-    )
-
+fun CartScreen(
+    onNavBarBack: () -> Unit,
+    viewModel: CartViewModel = viewModel(factory = LocalAppContainer.current.cartViewModelFactory)
+) {
     val cartState by viewModel.cartUiState.collectAsState()
 
     CartScreen(
@@ -200,7 +188,7 @@ fun CartItem(
 @Preview
 @Composable
 private fun CartScreenPreview() {
-    MyApplicationTheme {
+    FruittiesTheme {
         CartScreen(
             onNavBarBack = {},
             cartState = CartUiState(
@@ -240,7 +228,7 @@ private fun CartScreenPreview() {
 @Preview
 @Composable
 private fun CartItemPreview() {
-    MyApplicationTheme {
+    FruittiesTheme {
         CartItem(
             cartItem = CartItemDetails(
                 fruittie = Fruittie(
diff --git a/Fruitties/androidApp/src/main/java/com/example/fruitties/android/ui/FruittieScreen.kt b/Fruitties/androidApp/src/main/java/com/example/fruitties/android/ui/FruittieScreen.kt
@@ -22,12 +22,11 @@ import androidx.compose.runtime.Composable
 import androidx.compose.runtime.collectAsState
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
-import androidx.compose.ui.platform.LocalContext
 import androidx.compose.ui.res.stringResource
 import androidx.compose.ui.unit.dp
 import androidx.lifecycle.viewmodel.compose.viewModel
+import com.example.fruitties.android.LocalAppContainer
 import com.example.fruitties.android.R
-import com.example.fruitties.android.di.App
 import com.example.fruitties.model.Fruittie
 import com.example.fruitties.viewmodel.FruittieViewModel
 import com.example.fruitties.viewmodel.FruittieViewModel.Companion.FRUITTIE_ID_KEY
@@ -38,16 +37,13 @@ import com.example.fruitties.viewmodel.creationExtras
 fun FruittieScreen(
     fruittieId: Long,
     onNavBarBack: () -> Unit,
-) {
-    val app = LocalContext.current.applicationContext as App
-
-    val viewModel: FruittieViewModel = viewModel(
-        factory = FruittieViewModel.Factory,
-        extras = creationExtras(app.container) {
+    viewModel: FruittieViewModel = viewModel(
+        factory = LocalAppContainer.current.fruittieViewModelFactory,
+        extras = creationExtras {
             set(FRUITTIE_ID_KEY, fruittieId)
         },
     )
-
+) {
     val state = viewModel.state.collectAsState().value
 
     FruittieScreen(
diff --git a/Fruitties/androidApp/src/main/java/com/example/fruitties/android/ui/FruittiesTheme.kt b/Fruitties/androidApp/src/main/java/com/example/fruitties/android/ui/FruittiesTheme.kt
@@ -13,7 +13,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-package com.example.fruitties.android
+package com.example.fruitties.android.ui
 
 import androidx.compose.foundation.isSystemInDarkTheme
 import androidx.compose.foundation.shape.RoundedCornerShape
@@ -31,7 +31,7 @@ import androidx.compose.ui.unit.dp
 import androidx.compose.ui.unit.sp
 
 @Composable
-fun MyApplicationTheme(
+fun FruittiesTheme(
     darkTheme: Boolean = isSystemInDarkTheme(),
     content: @Composable () -> Unit,
 ) {
diff --git a/Fruitties/androidApp/src/main/java/com/example/fruitties/android/ui/ListScreen.kt b/Fruitties/androidApp/src/main/java/com/example/fruitties/android/ui/ListScreen.kt
@@ -45,35 +45,25 @@ import androidx.compose.runtime.getValue
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.input.nestedscroll.nestedScroll
-import androidx.compose.ui.platform.LocalContext
 import androidx.compose.ui.res.stringResource
 import androidx.compose.ui.text.style.TextOverflow
 import androidx.compose.ui.tooling.preview.Preview
 import androidx.compose.ui.unit.dp
 import androidx.lifecycle.viewmodel.compose.viewModel
+import com.example.fruitties.android.LocalAppContainer
 import com.example.fruitties.android.R
-import com.example.fruitties.android.di.App
 import com.example.fruitties.model.Fruittie
 import com.example.fruitties.viewmodel.MainViewModel
-import com.example.fruitties.viewmodel.creationExtras
 
 @OptIn(ExperimentalMaterial3Api::class)
 @Composable
 fun ListScreen(
     onClickViewCart: () -> Unit,
     onFruittieClick: (Fruittie) -> Unit,
-) {
-    // Instantiate a ViewModel with a dependency on the AppContainer.
-    // To make ViewModel compatible with KMP, the ViewModel factory must
-    // create an instance without referencing the Android Application.
-    // Here we put the KMP-compatible AppContainer into the extras
-    // so it can be passed to the ViewModel factory.
-    val app = LocalContext.current.applicationContext as App
-    val viewModel: MainViewModel = viewModel(
-        factory = MainViewModel.Factory,
-        extras = creationExtras(app.container),
+    viewModel: MainViewModel = viewModel(
+        factory = LocalAppContainer.current.mainViewModelFactory,
     )
-
+) {
     val uiState by viewModel.homeUiState.collectAsState()
     val topAppBarScrollBehavior = TopAppBarDefaults.enterAlwaysScrollBehavior()
     Scaffold(
@@ -135,7 +125,8 @@ fun FruittieItem(
         modifier = modifier
             .clickable {
                 onClick(item)
-            }.padding(16.dp),
+            }
+            .padding(16.dp),
         verticalAlignment = Alignment.CenterVertically,
     ) {
         Column(
diff --git a/Fruitties/iosApp/iosApp/ui/CartView.swift b/Fruitties/iosApp/iosApp/ui/CartView.swift
@@ -30,8 +30,7 @@ struct CartView: View {
         /// The `CartViewModel.Factory` and `creationExtras` are provided to enable dependency injection
         /// and proper initialization of the ViewModel with its required `AppContainer`.
         let cartViewModel: CartViewModel = viewModelStoreOwner.viewModel(
-            factory: CartViewModel.companion.Factory,
-            extras: creationExtras(appContainer: appContainer.value)
+            factory: appContainer.value.cartViewModelFactory,
         )
 
         /// Observes the `cartUiState` `StateFlow` from the `CartViewModel` using SKIE's `Observing` utility.
diff --git a/Fruitties/iosApp/iosApp/ui/ContentView.swift b/Fruitties/iosApp/iosApp/ui/ContentView.swift
@@ -30,8 +30,7 @@ struct ContentView: View {
         /// The `MainViewModel.Factory` and `creationExtras` are provided to enable dependency injection
         /// and proper initialization of the ViewModel with its required `AppContainer`.
         let mainViewModel: MainViewModel = viewModelStoreOwner.viewModel(
-            factory: MainViewModel.companion.Factory,
-            extras: creationExtras(appContainer: appContainer.value)
+            factory: appContainer.value.mainViewModelFactory,
         )
         NavigationStack {
             Observing(mainViewModel.homeUiState) { homeUIState in
diff --git a/Fruitties/iosApp/iosApp/ui/FruittieScreen.swift b/Fruitties/iosApp/iosApp/ui/FruittieScreen.swift
@@ -26,16 +26,13 @@ struct FruittieScreen: View {
     var body: some View {
         let fruittieViewModel: FruittieViewModel =
             viewModelStoreOwner.viewModel(
-                factory: FruittieViewModel.companion.Factory,
-                extras: creationExtras(
-                    appContainer: appContainer.value,
-                    additional: { extras in
-                        extras.set(
-                            key: FruittieViewModel.companion.FRUITTIE_ID_KEY,
-                            t: fruittie.id
-                        )
-                    }
-                )
+                factory: appContainer.value.fruittieViewModelFactory,
+                extras: creationExtras { extras in
+                    extras.set(
+                        key: FruittieViewModel.companion.FRUITTIE_ID_KEY,
+                        t: fruittie.id
+                    )
+                }
             )
 
         Observing(fruittieViewModel.state) { uiState in
diff --git a/Fruitties/shared/src/commonMain/kotlin/com/example/fruitties/di/AppContainer.kt b/Fruitties/shared/src/commonMain/kotlin/com/example/fruitties/di/AppContainer.kt
@@ -15,7 +15,14 @@
  */
 package com.example.fruitties.di
 
+import androidx.lifecycle.viewmodel.CreationExtras
+import androidx.lifecycle.viewmodel.initializer
+import androidx.lifecycle.viewmodel.viewModelFactory
 import com.example.fruitties.DataRepository
+import com.example.fruitties.viewmodel.CartViewModel
+import com.example.fruitties.viewmodel.FruittieViewModel
+import com.example.fruitties.viewmodel.FruittieViewModel.Companion.FRUITTIE_ID_KEY
+import com.example.fruitties.viewmodel.MainViewModel
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.SupervisorJob
@@ -31,4 +38,33 @@ class AppContainer(
             scope = CoroutineScope(Dispatchers.Default + SupervisorJob()),
         )
     }
-}
+
+    val mainViewModelFactory = viewModelFactory {
+        initializer {
+            MainViewModel(repository = dataRepository)
+        }
+    }
+
+    val cartViewModelFactory = viewModelFactory {
+        initializer {
+            CartViewModel(repository = dataRepository)
+        }
+    }
+
+    val fruittieViewModelFactory = viewModelFactory {
+        initializer {
+            FruittieViewModel(
+                fruittieId = get(FRUITTIE_ID_KEY) ?: error("Expected fruittieId!"),
+                repository = dataRepository,
+            )
+        }
+    }
+
+
+    fun fruittieViewModel(fruittieId: Long): CreationExtras.() -> FruittieViewModel = {
+        FruittieViewModel(
+            fruittieId = fruittieId,
+            repository = dataRepository,
+        )
+    }
+}
diff --git a/Fruitties/shared/src/commonMain/kotlin/com/example/fruitties/viewmodel/CartViewModel.kt b/Fruitties/shared/src/commonMain/kotlin/com/example/fruitties/viewmodel/CartViewModel.kt
@@ -62,12 +62,6 @@ class CartViewModel(
             repository.removeFromCart(cartItem.fruittie)
         }
     }
-
-    companion object {
-        val Factory: ViewModelProvider.Factory = fruittiesViewModelFactory {
-            CartViewModel(repository = it.dataRepository)
-        }
-    }
 }
 
 /**
diff --git a/Fruitties/shared/src/commonMain/kotlin/com/example/fruitties/viewmodel/FruittieViewModel.kt b/Fruitties/shared/src/commonMain/kotlin/com/example/fruitties/viewmodel/FruittieViewModel.kt
@@ -43,13 +43,6 @@ class FruittieViewModel(
     }
 
     companion object {
-        val Factory = fruittiesViewModelFactory {
-            FruittieViewModel(
-                fruittieId = get(FRUITTIE_ID_KEY) ?: error("Expected fruittieId!"),
-                repository = it.dataRepository,
-            )
-        }
-
         val FRUITTIE_ID_KEY = CreationExtras.Key<Long>()
     }
 }
diff --git a/Fruitties/shared/src/commonMain/kotlin/com/example/fruitties/viewmodel/MainViewModel.kt b/Fruitties/shared/src/commonMain/kotlin/com/example/fruitties/viewmodel/MainViewModel.kt
@@ -17,7 +17,6 @@
 package com.example.fruitties.viewmodel
 
 import androidx.lifecycle.ViewModel
-import androidx.lifecycle.ViewModelProvider
 import androidx.lifecycle.viewModelScope
 import co.touchlab.kermit.Logger
 import com.example.fruitties.DataRepository
@@ -59,12 +58,6 @@ class MainViewModel(
             repository.addToCart(fruittie)
         }
     }
-
-    companion object {
-        val Factory: ViewModelProvider.Factory = fruittiesViewModelFactory {
-            MainViewModel(repository = it.dataRepository)
-        }
-    }
 }
 
 /**
diff --git a/Fruitties/shared/src/commonMain/kotlin/com/example/fruitties/viewmodel/ViewModelFactory.kt b/Fruitties/shared/src/commonMain/kotlin/com/example/fruitties/viewmodel/ViewModelFactory.kt

Original file line number	Diff line number	Diff line change
`@@ -30,8 +30,7 @@ struct CartView: View {`
`30`	`30`	/// The `CartViewModel.Factory` and `creationExtras` are provided to enable dependency injection
`31`	`31`	/// and proper initialization of the ViewModel with its required `AppContainer`.
`32`	`32`	`let cartViewModel: CartViewModel = viewModelStoreOwner.viewModel(`
`33`		`- factory: CartViewModel.companion.Factory,`
`34`		`- extras: creationExtras(appContainer: appContainer.value)`
	`33`	`+ factory: appContainer.value.cartViewModelFactory,`
`35`	`34`	`)`
`36`	`35`
`37`	`36`	/// Observes the `cartUiState` `StateFlow` from the `CartViewModel` using SKIE's `Observing` utility.