Make CircularViewModel load LiveData from Room

app/src/main/java/net/underdesk/circolapp/adapters/CircularLetterAdapter.kt

@@ -46,7 +46,7 @@ import net.underdesk.circolapp.fragments.NewReminderFragment
 
 
 class CircularLetterAdapter(
-    private val circulars: List<Circular>,
+    private var circulars: List<Circular>,
     private val adapterCallback: AdapterCallback
 ) :
     RecyclerView.Adapter<CircularLetterAdapter.CircularLetterViewHolder>() {
@@ -208,6 +208,11 @@ class CircularLetterAdapter(
         }
     }
 
+    fun changeDataSet(newCirculars: List<Circular>) {
+        circulars = newCirculars
+        notifyDataSetChanged()
+    }
+
     override fun getItemCount() = circulars.size
 
     interface AdapterCallback {

app/src/main/java/net/underdesk/circolapp/data/CircularDao.kt

@@ -26,6 +26,9 @@ interface CircularDao {
     @Query("SELECT * FROM circulars ORDER BY id DESC")
     fun getCirculars(): List<Circular>
 
+    @Query("SELECT * FROM circulars ORDER BY id DESC")
+    fun getLiveCirculars(): LiveData<List<Circular>>
+
     @Query("SELECT * FROM circulars WHERE id = :id ORDER BY id DESC")
     fun getCircular(id: Long): Circular
 

app/src/main/java/net/underdesk/circolapp/fragments/CircularLetterFragment.kt

@@ -50,7 +50,11 @@ class CircularLetterFragment : Fragment() {
         circularLetterViewModel =
             ViewModelProviders.of(this).get(CircularLetterViewModel::class.java)
         circularLetterViewModel.circulars.observe(this, Observer {
-            root.circulars_list.adapter = CircularLetterAdapter(it, activity as MainActivity)
+            if (root.circulars_list.adapter == null) {
+                root.circulars_list.adapter = CircularLetterAdapter(it, activity as MainActivity)
+            } else {
+                (root.circulars_list.adapter as CircularLetterAdapter).changeDataSet(it)
+            }
         })
         circularLetterViewModel.showMessage.observe(this, Observer {
             if (it) activity?.findViewById<ConstraintLayout>(R.id.container)?.let { view ->

app/src/main/java/net/underdesk/circolapp/fragments/FavouritesFragment.kt

@@ -48,7 +48,11 @@ class FavouritesFragment : Fragment() {
         favouritesViewModel =
             ViewModelProviders.of(this).get(FavouritesViewModel::class.java)
         favouritesViewModel.circulars.observe(this, Observer {
-            root.circulars_list.adapter = CircularLetterAdapter(it, activity as MainActivity)
+            if (root.circulars_list.adapter == null) {
+                root.circulars_list.adapter = CircularLetterAdapter(it, activity as MainActivity)
+            } else {
+                (root.circulars_list.adapter as CircularLetterAdapter).changeDataSet(it)
+            }
         })
         return root
     }

app/src/main/java/net/underdesk/circolapp/fragments/RemindersFragment.kt

@@ -48,7 +48,11 @@ class RemindersFragment : Fragment() {
         remindersViewModel =
             ViewModelProviders.of(this).get(RemindersViewModel::class.java)
         remindersViewModel.circulars.observe(this, Observer {
-            root.circulars_list.adapter = CircularLetterAdapter(it, activity as MainActivity)
+            if (root.circulars_list.adapter == null) {
+                root.circulars_list.adapter = CircularLetterAdapter(it, activity as MainActivity)
+            } else {
+                (root.circulars_list.adapter as CircularLetterAdapter).changeDataSet(it)
+            }
         })
         return root
     }

app/src/main/java/net/underdesk/circolapp/viewmodels/CircularLetterViewModel.kt

@@ -28,32 +28,25 @@ import net.underdesk.circolapp.server.DataFetcher
 import java.io.IOException
 
 class CircularLetterViewModel(application: Application) : AndroidViewModel(application) {
-
+    init {
-    private val _circulars: MutableLiveData<List<Circular>> by lazy {
-        MutableLiveData<List<Circular>>().also {
-            loadCirculars()
-        }
-    }
-
-    val circulars: LiveData<List<Circular>> = _circulars
-    val showMessage = MutableLiveData<Boolean>().apply { value = false }
-
-    private fun loadCirculars() {
         object : Thread() {
             override fun run() {
-                _circulars.postValue(AppDatabase.getInstance(getApplication()).circularDao().getCirculars())
                 updateCirculars()
             }
         }.start()
     }
 
+    val circulars: LiveData<List<Circular>> =
+        AppDatabase.getInstance(getApplication()).circularDao().getLiveCirculars()
+
+    val showMessage = MutableLiveData<Boolean>().apply { value = false }
+
     private fun updateCirculars() {
         val fetcher = DataFetcher()
 
         try {
             val newCirculars = fetcher.getCircularsFromServer()
-            if (newCirculars.size != _circulars.value?.size ?: true) {
+            if (newCirculars.size != circulars.value?.size ?: true) {
-                _circulars.postValue(newCirculars)
                 AppDatabase.getInstance(getApplication()).circularDao().deleteAll()
                 AppDatabase.getInstance(getApplication()).circularDao().insertAll(newCirculars)
             }