Merge remote-tracking branch 'github/main' into bug-fix459/top-bar2

Author: JoseAlcerreca

Crane/app/src/release/res/values/google_maps_api.xml

@@ -106,16 +106,16 @@ dependencies {
  implementation "com.google.accompanist:accompanist-insets:$accompanist_version"
  implementation "com.google.accompanist:accompanist-systemuicontroller:$accompanist_version"
 
- implementation 'androidx.appcompat:appcompat:1.3.0'
- implementation 'androidx.activity:activity-ktx:1.2.3'
+ implementation 'androidx.appcompat:appcompat:1.3.1'
+ implementation 'androidx.activity:activity-ktx:1.3.1'
  implementation 'androidx.core:core-ktx:1.6.0'
  implementation "androidx.activity:activity-compose:1.3.1"
 
  implementation "androidx.lifecycle:lifecycle-viewmodel-savedstate:2.3.1"
  implementation "androidx.lifecycle:lifecycle-livedata-ktx:2.3.1"
  implementation "androidx.lifecycle:lifecycle-viewmodel-compose:1.0.0-alpha07"
 
- implementation 'androidx.navigation:navigation-compose:2.4.0-alpha06'
+ implementation 'androidx.navigation:navigation-compose:2.4.0-alpha07'
 
  androidTestImplementation 'androidx.test:core:1.4.0'
  androidTestImplementation 'androidx.test:rules:1.4.0'

JetNews/app/build.gradle

@@ -20,17 +20,10 @@ package com.example.jetnews.data
  * A generic class that holds a value or an exception
  */
 sealed class Result<out R> {
-
  data class Success<out T>(val data: T) : Result<T>()
  data class Error(val exception: Exception) : Result<Nothing>()
 }
 
-/**
- * `true` if [Result] is of type [Success] & holds non-null [Success.data].
- */
-val Result<*>.succeeded
- get() = this is Result.Success && data != null
-
 fun <T> Result<T>.successOr(fallback: T): T {
  return (this as? Result.Success<T>)?.data ?: fallback
 }

JetNews/app/src/main/java/com/example/jetnews/data/Result.kt

@@ -21,15 +21,21 @@ import androidx.compose.material.rememberScaffoldState
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.remember
 import androidx.compose.runtime.rememberCoroutineScope
+import androidx.lifecycle.viewmodel.compose.viewModel
 import androidx.navigation.NavHostController
+import androidx.navigation.NavType
 import androidx.navigation.compose.NavHost
 import androidx.navigation.compose.composable
+import androidx.navigation.compose.navArgument
 import androidx.navigation.compose.rememberNavController
 import com.example.jetnews.data.AppContainer
-import com.example.jetnews.ui.MainDestinations.ARTICLE_ID_KEY
 import com.example.jetnews.ui.article.ArticleScreen
+import com.example.jetnews.ui.article.ArticleViewModel
+import com.example.jetnews.ui.article.ArticleViewModel.Companion.ARTICLE_ID_KEY
 import com.example.jetnews.ui.home.HomeScreen
+import com.example.jetnews.ui.home.HomeViewModel
 import com.example.jetnews.ui.interests.InterestsScreen
+import com.example.jetnews.ui.interests.InterestsViewModel
 import kotlinx.coroutines.launch
 
 /**
@@ -39,7 +45,6 @@ object MainDestinations {
  const val HOME_ROUTE = "home"
  const val INTERESTS_ROUTE = "interests"
  const val ARTICLE_ROUTE = "post"
- const val ARTICLE_ID_KEY = "postId"
 }
 
 @Composable
@@ -58,23 +63,39 @@ fun JetnewsNavGraph(
  startDestination = startDestination
  ) {
  composable(MainDestinations.HOME_ROUTE) {
+ val homeViewModel: HomeViewModel = viewModel(
+ factory = HomeViewModel.provideFactory(appContainer.postsRepository)
+ )
  HomeScreen(
- postsRepository = appContainer.postsRepository,
+ homeViewModel = homeViewModel,
  navigateToArticle = actions.navigateToArticle,
  openDrawer = openDrawer
  )
  }
  composable(MainDestinations.INTERESTS_ROUTE) {
+ val interestsViewModel: InterestsViewModel = viewModel(
+ factory = InterestsViewModel.provideFactory(appContainer.interestsRepository)
+ )
  InterestsScreen(
- interestsRepository = appContainer.interestsRepository,
+ interestsViewModel = interestsViewModel,
  openDrawer = openDrawer
  )
  }
- composable("${MainDestinations.ARTICLE_ROUTE}/{$ARTICLE_ID_KEY}") { backStackEntry ->
+ composable(
+ route = "${MainDestinations.ARTICLE_ROUTE}/{$ARTICLE_ID_KEY}",
+ arguments = listOf(navArgument(ARTICLE_ID_KEY) { type = NavType.StringType })
+ ) { backStackEntry ->
+ // ArticleVM obtains the articleId via backStackEntry.arguments from SavedStateHandle
+ val articleViewModel: ArticleViewModel = viewModel(
+ factory = ArticleViewModel.provideFactory(
+ postsRepository = appContainer.postsRepository,
+ owner = backStackEntry,
+ defaultArgs = backStackEntry.arguments
+ )
+ )
  ArticleScreen(
- postId = backStackEntry.arguments?.getString(ARTICLE_ID_KEY),
- onBack = actions.upPress,
- postsRepository = appContainer.postsRepository
+ articleViewModel = articleViewModel,
+ onBack = actions.upPress
  )
  }
  }

JetNews/app/src/main/java/com/example/jetnews/ui/JetnewsNavGraph.kt

@@ -43,10 +43,10 @@ import androidx.compose.material.icons.filled.ArrowBack
 import androidx.compose.material.icons.filled.Share
 import androidx.compose.material.icons.filled.ThumbUpOffAlt
 import androidx.compose.runtime.Composable
+import androidx.compose.runtime.LaunchedEffect
 import androidx.compose.runtime.collectAsState
 import androidx.compose.runtime.getValue
 import androidx.compose.runtime.mutableStateOf
-import androidx.compose.runtime.rememberCoroutineScope
 import androidx.compose.runtime.saveable.rememberSaveable
 import androidx.compose.runtime.setValue
 import androidx.compose.ui.Alignment
@@ -60,58 +60,47 @@ import androidx.compose.ui.tooling.preview.Preview
 import androidx.compose.ui.unit.dp
 import com.example.jetnews.R
 import com.example.jetnews.data.Result
-import com.example.jetnews.data.posts.PostsRepository
 import com.example.jetnews.data.posts.impl.BlockingFakePostsRepository
 import com.example.jetnews.data.posts.impl.post3
 import com.example.jetnews.model.Post
 import com.example.jetnews.ui.components.InsetAwareTopAppBar
 import com.example.jetnews.ui.home.BookmarkButton
 import com.example.jetnews.ui.theme.JetnewsTheme
 import com.example.jetnews.utils.isScrolled
-import com.example.jetnews.utils.produceUiState
 import com.example.jetnews.utils.supportWideScreen
 import com.google.accompanist.insets.navigationBarsPadding
-import kotlinx.coroutines.launch
 import kotlinx.coroutines.runBlocking
 
 /**
- * Stateful Article Screen that manages state using [produceUiState]
+ * Displays the Article screen.
  *
- * @param postId (state) the post to show
- * @param postsRepository data source for this screen
+ * @param articleViewModel ViewModel that handles the business logic of this screen
  * @param onBack (event) request back navigation
  */
-@Suppress("DEPRECATION") // allow ViewModelLifecycleScope call
 @Composable
 fun ArticleScreen(
- postId: String?,
- postsRepository: PostsRepository,
+ articleViewModel: ArticleViewModel,
  onBack: () -> Unit
 ) {
- val (post) = produceUiState(postsRepository, postId) {
- getPost(postId)
- }
- // TODO: handle errors when the repository is capable of creating them
- val postData = post.value.data ?: return
-
- // [collectAsState] will automatically collect a Flow<T> and return a State<T> object that
- // updates whenever the Flow emits a value. Collection is cancelled when [collectAsState] is
- // removed from the composition tree.
- val favorites by postsRepository.observeFavorites().collectAsState(setOf())
- val isFavorite = favorites.contains(postId)
+ // UiState of the ArticleScreen
+ val uiState by articleViewModel.uiState.collectAsState()
 
- // Returns a [CoroutineScope] that is scoped to the lifecycle of [ArticleScreen]. When this
- // screen is removed from composition, the scope will be cancelled.
- val coroutineScope = rememberCoroutineScope()
+ if (uiState.post != null) {
+ ArticleScreen(
+ post = uiState.post!!,
+ onBack = onBack,
+ isFavorite = uiState.isFavorite,
+ onToggleFavorite = { articleViewModel.toggleFavorite() }
+ )
+ }
 
- ArticleScreen(
- post = postData,
- onBack = onBack,
- isFavorite = isFavorite,
- onToggleFavorite = {
- coroutineScope.launch { postId?.let { postsRepository.toggleFavorite(postId) } }
+ // Check for failures while loading the state
+ // TODO: Improve UX
+ LaunchedEffect(uiState) {
+ if (uiState.failedLoading) {
+ onBack()
  }
- )
+ }
 }
 
 /**

JetNews/app/src/main/java/com/example/jetnews/ui/article/ArticleScreen.kt

@@ -0,0 +1,109 @@
+/*
+ * Copyright 2021 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.example.jetnews.ui.article
+
+import android.os.Bundle
+import androidx.lifecycle.AbstractSavedStateViewModelFactory
+import androidx.lifecycle.SavedStateHandle
+import androidx.lifecycle.ViewModel
+import androidx.lifecycle.viewModelScope
+import androidx.savedstate.SavedStateRegistryOwner
+import com.example.jetnews.data.Result
+import com.example.jetnews.data.posts.PostsRepository
+import com.example.jetnews.model.Post
+import kotlinx.coroutines.flow.MutableStateFlow
+import kotlinx.coroutines.flow.StateFlow
+import kotlinx.coroutines.flow.asStateFlow
+import kotlinx.coroutines.flow.collect
+import kotlinx.coroutines.flow.update
+import kotlinx.coroutines.launch
+
+/**
+ * UI state for the Article screen
+ */
+data class ArticleUiState(
+ val post: Post? = null,
+ val isFavorite: Boolean = false,
+ val loading: Boolean = false
+) {
+ /**
+ * True if the post couldn't be found
+ */
+ val failedLoading: Boolean
+ get() = !loading && post == null
+}
+
+class ArticleViewModel(
+ private val postsRepository: PostsRepository,
+ savedStateHandle: SavedStateHandle
+) : ViewModel() {
+
+ private val postId: String = savedStateHandle.get<String>(ARTICLE_ID_KEY)!!
+
+ // UI state exposed to the UI
+ private val _uiState = MutableStateFlow(ArticleUiState(loading = true))
+ val uiState: StateFlow<ArticleUiState> = _uiState.asStateFlow()
+
+ init {
+ // Load post
+ viewModelScope.launch {
+ val postResult = postsRepository.getPost(postId)
+ _uiState.update {
+ when (postResult) {
+ is Result.Success -> it.copy(post = postResult.data, loading = false)
+ is Result.Error -> it.copy(loading = false)
+ }
+ }
+ }
+
+ // Update whether the post is favorite or not
+ viewModelScope.launch {
+ postsRepository.observeFavorites().collect { favorites ->
+ _uiState.update { it.copy(isFavorite = favorites.contains(postId)) }
+ }
+ }
+ }
+
+ fun toggleFavorite() {
+ viewModelScope.launch {
+ postsRepository.toggleFavorite(postId)
+ }
+ }
+
+ /**
+ * Factory for ArticleViewModel that takes PostsRepository as a dependency
+ */
+ companion object {
+ const val ARTICLE_ID_KEY = "postId"
+
+ fun provideFactory(
+ postsRepository: PostsRepository,
+ owner: SavedStateRegistryOwner,
+ defaultArgs: Bundle? = null,
+ ): AbstractSavedStateViewModelFactory =
+ object : AbstractSavedStateViewModelFactory(owner, defaultArgs) {
+ @Suppress("UNCHECKED_CAST")
+ override fun <T : ViewModel?> create(
+ key: String,
+ modelClass: Class<T>,
+ handle: SavedStateHandle
+ ): T {
+ return ArticleViewModel(postsRepository, handle) as T
+ }
+ }
+ }
+}