Merge pull request #57 from PatilShreyas/hilt-update

Use @AssistedInject for PostDetailsViewModel
PatilShreyas · Jan 16, 2021 · 8b49abb · 8b49abb
2 parents 11a47c1 + aa74f32
commit 8b49abb
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Showing 4 changed files with 52 additions and 27 deletions.
diff --git a/app/src/main/java/dev/shreyaspatil/foodium/data/repository/PostRepository.kt b/app/src/main/java/dev/shreyaspatil/foodium/data/repository/PostRepository.kt
@@ -32,9 +32,7 @@ import kotlinx.coroutines.ExperimentalCoroutinesApi
 import kotlinx.coroutines.flow.Flow
 import retrofit2.Response
 import javax.inject.Inject
-import javax.inject.Singleton
 
-@Singleton
 interface PostRepository {
     fun getAllPosts(): Flow<Resource<List<Post>>>
     fun getPostById(postId: Int): Flow<Post>
@@ -45,7 +43,6 @@ interface PostRepository {
  * for offline capability. This is Single source of data.
  */
 @ExperimentalCoroutinesApi
-@Singleton
 class DefaultPostRepository @Inject constructor(
     private val postsDao: PostsDao,
     private val foodiumService: FoodiumService

diff --git a/app/src/main/java/dev/shreyaspatil/foodium/di/module/PostRepositoryModule.kt b/app/src/main/java/dev/shreyaspatil/foodium/di/module/PostRepositoryModule.kt
@@ -27,18 +27,22 @@ package dev.shreyaspatil.foodium.di.module
 import dagger.Binds
 import dagger.Module
 import dagger.hilt.InstallIn
-import dagger.hilt.android.components.ViewModelComponent
-import dagger.hilt.android.scopes.ViewModelScoped
+import dagger.hilt.android.components.ActivityRetainedComponent
+import dagger.hilt.android.scopes.ActivityRetainedScoped
 import dev.shreyaspatil.foodium.data.repository.DefaultPostRepository
 import dev.shreyaspatil.foodium.data.repository.PostRepository
 import kotlinx.coroutines.ExperimentalCoroutinesApi
 
+/**
+ * Currently PostRepository is only used in ViewModels.
+ * PostDetailsViewModel is not injected using @HiltViewModel so can't install in ViewModelComponent.
+ */
 @ExperimentalCoroutinesApi
-@InstallIn(ViewModelComponent::class)
+@InstallIn(ActivityRetainedComponent::class)
 @Module
 abstract class PostRepositoryModule {
 
-    @ViewModelScoped
+    @ActivityRetainedScoped
     @Binds
     abstract fun bindPostRepository(repository: DefaultPostRepository): PostRepository
 }
diff --git a/app/src/main/java/dev/shreyaspatil/foodium/ui/details/PostDetailsActivity.kt b/app/src/main/java/dev/shreyaspatil/foodium/ui/details/PostDetailsActivity.kt
@@ -24,8 +24,8 @@
 
 package dev.shreyaspatil.foodium.ui.details
 
-import android.content.Intent
 import android.content.Context
+import android.content.Intent
 import android.os.Bundle
 import android.view.Menu
 import android.view.MenuItem
@@ -35,36 +35,40 @@ import coil.load
 import dagger.hilt.android.AndroidEntryPoint
 import dev.shreyaspatil.foodium.R
 import dev.shreyaspatil.foodium.databinding.ActivityPostDetailsBinding
-import dev.shreyaspatil.foodium.model.Post
 import dev.shreyaspatil.foodium.ui.base.BaseActivity
 import kotlinx.coroutines.ExperimentalCoroutinesApi
+import javax.inject.Inject
 
 @ExperimentalCoroutinesApi
 @AndroidEntryPoint
 class PostDetailsActivity : BaseActivity<PostDetailsViewModel, ActivityPostDetailsBinding>() {
 
-    override val mViewModel: PostDetailsViewModel by viewModels()
+    @Inject
+    lateinit var viewModelFactory: PostDetailsViewModel.PostDetailsViewModelFactory
 
-    private lateinit var post: Post
+    override val mViewModel: PostDetailsViewModel by viewModels {
+        val postId = intent.extras?.getInt(KEY_POST_ID)
+            ?: throw IllegalArgumentException("`postId` must be non-null")
+
+        PostDetailsViewModel.provideFactory(viewModelFactory, postId)
+    }
 
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
         setContentView(mViewBinding.root)
 
         setSupportActionBar(mViewBinding.toolbar)
         supportActionBar?.setDisplayHomeAsUpEnabled(true)
+    }
 
-        val postId = intent.extras?.getInt(POST_ID)
-            ?: throw IllegalArgumentException("`postId` must be non-null")
-
-        initPost(postId)
+    override fun onStart() {
+        super.onStart()
+        initPost()
     }
 
-    private fun initPost(postId: Int) {
-        mViewModel.getPost(postId).observe(this) { post ->
+    private fun initPost() {
+        mViewModel.post.observe(this) { post ->
             mViewBinding.postContent.apply {
-                this@PostDetailsActivity.post = post
-
                 postTitle.text = post.title
                 postAuthor.text = post.author
                 postBody.text = post.body
@@ -74,6 +78,7 @@ class PostDetailsActivity : BaseActivity<PostDetailsViewModel, ActivityPostDetai
     }
 
     private fun share() {
+        val post = mViewModel.post.value ?: return
         val shareMsg = getString(R.string.share_message, post.title, post.author)
 
         val intent = ShareCompat.IntentBuilder.from(this)
@@ -109,11 +114,11 @@ class PostDetailsActivity : BaseActivity<PostDetailsViewModel, ActivityPostDetai
     }
 
     companion object {
-        private const val POST_ID = "postId"
+        private const val KEY_POST_ID = "postId"
 
         fun getStartIntent(
             context: Context,
             postId: Int
-        ) = Intent(context, PostDetailsActivity::class.java).apply { putExtra(POST_ID, postId) }
+        ) = Intent(context, PostDetailsActivity::class.java).apply { putExtra(KEY_POST_ID, postId) }
     }
 }
diff --git a/app/src/main/java/dev/shreyaspatil/foodium/ui/details/PostDetailsViewModel.kt b/app/src/main/java/dev/shreyaspatil/foodium/ui/details/PostDetailsViewModel.kt
@@ -25,20 +25,39 @@
 package dev.shreyaspatil.foodium.ui.details
 
 import androidx.lifecycle.ViewModel
+import androidx.lifecycle.ViewModelProvider
 import androidx.lifecycle.asLiveData
-import dagger.hilt.android.lifecycle.HiltViewModel
+import dagger.assisted.Assisted
+import dagger.assisted.AssistedFactory
+import dagger.assisted.AssistedInject
 import dev.shreyaspatil.foodium.data.repository.PostRepository
 import kotlinx.coroutines.ExperimentalCoroutinesApi
-import javax.inject.Inject
 
 /**
  * ViewModel for [PostDetailsActivity]
  */
 @ExperimentalCoroutinesApi
-@HiltViewModel
-class PostDetailsViewModel @Inject constructor(
-    private val postRepository: PostRepository
+class PostDetailsViewModel @AssistedInject constructor(
+    postRepository: PostRepository,
+    @Assisted postId: Int
 ) : ViewModel() {
 
-    fun getPost(id: Int) = postRepository.getPostById(id).asLiveData()
+    val post = postRepository.getPostById(postId).asLiveData()
+
+    @AssistedFactory
+    interface PostDetailsViewModelFactory {
+        fun create(postId: Int): PostDetailsViewModel
+    }
+
+    @Suppress("UNCHECKED_CAST")
+    companion object {
+        fun provideFactory(
+            assistedFactory: PostDetailsViewModelFactory,
+            postId: Int
+        ): ViewModelProvider.Factory = object : ViewModelProvider.Factory {
+            override fun <T : ViewModel?> create(modelClass: Class<T>): T {
+                return assistedFactory.create(postId) as T
+            }
+        }
+    }
 }