Merge pull request #8 from liip/initial-value

Initial value
liip · Jul 26, 2019 · 6992c63 · 6992c63
2 parents af3f8e5 + 1a4dae2
commit 6992c63
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Showing 4 changed files with 39 additions and 6 deletions.
diff --git a/demo/src/main/java/ch/liip/viewmodelsavedstatehelpers/demo/MainActivity.kt b/demo/src/main/java/ch/liip/viewmodelsavedstatehelpers/demo/MainActivity.kt
@@ -20,10 +20,12 @@ class MainActivity : AppCompatActivity() {
 
         // Set the value manually during creation
         manualText.setText(viewModel.manualText)
+        manualValue.setText(viewModel.manualText)
 
         // Observe the livedata
         viewModel.liveDataText.observe(this, Observer {
             liveDataText.setText(it)
+            liveDataValue.setText(it)
         })
 
         // Save the values

diff --git a/demo/src/main/java/ch/liip/viewmodelsavedstatehelpers/demo/MainViewModel.kt b/demo/src/main/java/ch/liip/viewmodelsavedstatehelpers/demo/MainViewModel.kt
@@ -11,4 +11,7 @@ class MainViewModel(handle: SavedStateHandle) : ViewModel() {
 
     // MutableLiveData that is saved in the SavedState
     val liveDataText by handle.livedata<String?>()
+
+    // Could be used with a default value
+    // val liveDataText by handle.livedata<String?>(initialValue = "Hello")
 }
diff --git a/demo/src/main/res/layout/activity_main.xml b/demo/src/main/res/layout/activity_main.xml
@@ -28,12 +28,12 @@
         android:layout_height="wrap_content"
         android:layout_marginStart="8dp"
         android:layout_marginTop="8dp"
-        android:layout_marginEnd="8dp"
         android:layout_marginBottom="8dp"
         android:hint="@string/editTextHint"
         android:inputType="text"
         app:layout_constraintBottom_toTopOf="@id/liveDataText"
-        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintEnd_toStartOf="@+id/manualValue"
+        app:layout_constraintHorizontal_bias="0.5"
         app:layout_constraintStart_toStartOf="parent"
         app:layout_constraintTop_toBottomOf="@+id/info" />
 
@@ -43,12 +43,12 @@
         android:layout_height="wrap_content"
         android:layout_marginStart="8dp"
         android:layout_marginTop="8dp"
-        android:layout_marginEnd="8dp"
         android:layout_marginBottom="8dp"
         android:hint="@string/editTextHint"
         android:inputType="text"
         app:layout_constraintBottom_toTopOf="@id/button"
-        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintEnd_toStartOf="@+id/liveDataValue"
+        app:layout_constraintHorizontal_bias="0.5"
         app:layout_constraintStart_toStartOf="parent"
         app:layout_constraintTop_toBottomOf="@id/manualText" />
 
@@ -63,4 +63,28 @@
         app:layout_constraintStart_toStartOf="parent"
         app:layout_constraintTop_toBottomOf="@id/liveDataText" />
 
+    <TextView
+        android:id="@+id/manualValue"
+        android:layout_width="0dp"
+        android:layout_height="wrap_content"
+        android:layout_marginStart="8dp"
+        android:layout_marginEnd="8dp"
+        app:layout_constraintBottom_toBottomOf="@+id/manualText"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintHorizontal_bias="0.5"
+        app:layout_constraintStart_toEndOf="@+id/manualText"
+        app:layout_constraintTop_toTopOf="@+id/manualText"
+        tools:text="TextView" />
+
+    <TextView
+        android:id="@+id/liveDataValue"
+        android:layout_width="0dp"
+        android:layout_height="wrap_content"
+        app:layout_constraintBottom_toBottomOf="@+id/liveDataText"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintHorizontal_bias="0.5"
+        app:layout_constraintStart_toEndOf="@+id/liveDataText"
+        app:layout_constraintTop_toTopOf="@+id/liveDataText"
+        tools:text="TextView" />
+
 </android.support.constraint.ConstraintLayout>
diff --git a/library/src/main/java/ch/liip/viewmodelsavedstatehelpers/SavedStateHandleDelegate.kt b/library/src/main/java/ch/liip/viewmodelsavedstatehelpers/SavedStateHandleDelegate.kt
@@ -18,9 +18,13 @@ inline fun <reified T> SavedStateHandle.delegate(key: String? = null): ReadWrite
     }
 }
 
-inline fun <reified T> SavedStateHandle.livedata(key: String? = null) = object : ReadOnlyProperty<Any, MutableLiveData<T?>> {
+inline fun <reified T> SavedStateHandle.livedata(key: String? = null, initialValue: T? = null) = object : ReadOnlyProperty<Any, MutableLiveData<T?>> {
     override fun getValue(thisRef: Any, property: KProperty<*>): MutableLiveData<T?> {
         val stateKey = key ?: property.name
-        return this@livedata.getLiveData(stateKey)
+        return if (initialValue == null) {
+            this@livedata.getLiveData(stateKey)
+        } else {
+            this@livedata.getLiveData(stateKey, initialValue)
+        }
     }
 }