Add LiveData and ViewModel to fragments

Author: daniel-stoneuk

app/build.gradle.kts

@@ -45,6 +45,8 @@ dependencies {
     implementation("com.google.android.material:material:1.3.0-alpha01")
     implementation("com.apollographql.apollo:apollo-runtime:2.2.2")
     implementation("com.apollographql.apollo:apollo-coroutines-support:2.2.2")
+    implementation("androidx.lifecycle:lifecycle-livedata-ktx:2.2.0")
+
 }
 
 apollo {

app/src/main/java/guide/graphql/toc/ChaptersFragment.kt

@@ -2,12 +2,30 @@ package guide.graphql.toc
 
 import android.os.Bundle
 import androidx.appcompat.app.AppCompatActivity
+import androidx.navigation.NavController
+import androidx.navigation.findNavController
 
 class MainActivity : AppCompatActivity() {
 
+    private val navigationListener = NavController.OnDestinationChangedListener { controller, destination, arguments ->
+        if (destination.id == R.id.chapters_fragment) {
+            this.setTitle(R.string.app_name)
+        }
+    }
+
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
 
         setContentView(R.layout.activity_main)
     }
+
+    override fun onResume() {
+        super.onResume()
+        findNavController(R.id.nav_host_fragment).addOnDestinationChangedListener(navigationListener)
+    }
+
+    override fun onPause() {
+        super.onPause()
+        findNavController(R.id.nav_host_fragment).removeOnDestinationChangedListener(navigationListener)
+    }
 }

app/src/main/java/guide/graphql/toc/MainActivity.kt

@@ -0,0 +1,24 @@
+package guide.graphql.toc
+
+//https://github.com/android/architecture-components-samples/blob/master/GithubBrowserSample/app/src/main/java/com/android/example/github/vo/Resource.kt
+
+data class Resource<out T>(val status: Status, val data: T?, val message: String?) {
+    companion object {
+        fun <T> success(data: T?): Resource<T> {
+            return Resource(Status.SUCCESS, data, null)
+        }
+
+        fun <T> error(msg: String, data: T?): Resource<T> {
+            return Resource(Status.ERROR, data, msg)
+        }
+
+        fun <T> loading(data: T?): Resource<T> {
+            return Resource(Status.LOADING, data, null)
+        }
+    }
+}
+enum class Status {
+    SUCCESS,
+    ERROR,
+    LOADING
+}

app/src/main/java/guide/graphql/toc/Resource.kt

@@ -1,21 +1,28 @@
-package guide.graphql.toc
+package guide.graphql.toc.ui.chapters
 
 import android.content.Context
 import android.view.LayoutInflater
 import android.view.View
 import android.view.ViewGroup
 import androidx.recyclerview.widget.RecyclerView
+import guide.graphql.toc.ChaptersQuery
+import guide.graphql.toc.R
 import guide.graphql.toc.databinding.ChapterBinding
 
 class ChaptersAdapter(
-    private val chapters: List<ChaptersQuery.Chapter>,
+    private var chapters: List<ChaptersQuery.Chapter>,
     private val context: Context,
     private val onItemClicked: ((ChaptersQuery.Chapter) -> Unit)
 ) :
     RecyclerView.Adapter<ChaptersAdapter.ViewHolder>() {
 
     class ViewHolder(val binding: ChapterBinding) : RecyclerView.ViewHolder(binding.root)
 
+    fun updateChapters(chapters: List<ChaptersQuery.Chapter>) {
+        this.chapters = chapters
+        notifyDataSetChanged()
+    }
+
     override fun getItemCount(): Int {
         return chapters.size
     }

app/src/main/java/guide/graphql/toc/SectionsFragment.kt

@@ -0,0 +1,77 @@
+package guide.graphql.toc.ui.chapters
+
+import android.os.Bundle
+import android.view.LayoutInflater
+import android.view.View
+import android.view.ViewGroup
+import android.widget.Toast
+import androidx.appcompat.app.AppCompatActivity
+import androidx.fragment.app.Fragment
+import androidx.fragment.app.viewModels
+import androidx.lifecycle.Observer
+import androidx.navigation.fragment.findNavController
+import androidx.recyclerview.widget.DividerItemDecoration
+import androidx.recyclerview.widget.LinearLayoutManager
+import com.google.android.material.transition.MaterialFade
+import guide.graphql.toc.Status
+import guide.graphql.toc.databinding.ChaptersFragmentBinding
+
+class ChaptersFragment : Fragment() {
+
+    private val viewModel: ChaptersViewModel by viewModels()
+
+    private lateinit var binding: ChaptersFragmentBinding
+
+    override fun onCreateView(
+        inflater: LayoutInflater,
+        container: ViewGroup?,
+        savedInstanceState: Bundle?
+    ): View? {
+        binding = ChaptersFragmentBinding.inflate(inflater)
+        return binding.root
+    }
+
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        val materialFade = MaterialFade()
+        exitTransition = materialFade
+
+    }
+
+    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
+        super.onViewCreated(view, savedInstanceState)
+
+        (requireActivity() as AppCompatActivity).setSupportActionBar(binding.bookHeader)
+
+        val adapter =
+            ChaptersAdapter(
+                listOf(),
+                requireContext()
+            ) { chapter ->
+                findNavController().navigate(
+                    ChaptersFragmentDirections.viewSections(
+                        chapterId = chapter.id,
+                        chapterNumber = chapter.number?.toInt() ?: -1,
+                        chapterTitle = chapter.title
+                    )
+                )
+            }
+        val layoutManager = LinearLayoutManager(requireContext())
+        binding.chapters.layoutManager = layoutManager
+        val itemDivider = DividerItemDecoration(requireContext(), layoutManager.orientation)
+        binding.chapters.addItemDecoration(itemDivider)
+        binding.chapters.adapter = adapter
+
+        viewModel.chapterList.observe(viewLifecycleOwner, Observer { chapterListResponse ->
+            when (chapterListResponse.status) {
+                Status.SUCCESS -> {
+                    chapterListResponse.data?.let {
+                        adapter.updateChapters(it)
+                    }
+                }
+                Status.ERROR -> Toast.makeText(requireContext(), "Error: ${chapterListResponse.message}", Toast.LENGTH_SHORT).show()
+            }
+        })
+
+    }
+}