[shared_preferences] Added reload method

packages/shared_preferences/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 0.5.3
+
+* Add reload method.
+
 ## 0.5.2+2
 
 * Updated Gradle tooling to match Android Studio 3.4.

packages/shared_preferences/lib/shared_preferences.dart

@@ -21,18 +21,8 @@ class SharedPreferences {
   static SharedPreferences _instance;
   static Future<SharedPreferences> getInstance() async {
     if (_instance == null) {
-      final Map<Object, Object> fromSystem =
-          // TODO(amirh): remove this on when the invokeMethod update makes it to stable Flutter.
-          // https://github.com/flutter/flutter/issues/26431
-          // ignore: strong_mode_implicit_dynamic_method
-          await _kChannel.invokeMethod('getAll');
-      assert(fromSystem != null);
-      // Strip the flutter. prefix from the returned preferences.
-      final Map<String, Object> preferencesMap = <String, Object>{};
-      for (String key in fromSystem.keys) {
-        assert(key.startsWith(_prefix));
-        preferencesMap[key.substring(_prefix.length)] = fromSystem[key];
-      }
+      final Map<String, Object> preferencesMap =
+          await _getSharedPreferencesMap();
       _instance = SharedPreferences._(preferencesMap);
     }
     return _instance;
@@ -158,6 +148,30 @@ class SharedPreferences {
     return await _kChannel.invokeMethod('clear');
   }
 
+  /// Fetches the latest values from the host platform.
+  ///
+  /// Use this method to observe modifications that were made in native code
+  /// (without using the plugin) while the app is running.
+  Future<void> reload() async {
+    final Map<String, Object> preferences =
+        await SharedPreferences._getSharedPreferencesMap();
+    _preferenceCache.clear();
+    _preferenceCache.addAll(preferences);
+  }
+
+  static Future<Map<String, Object>> _getSharedPreferencesMap() async {
+    final Map<Object, Object> fromSystem =
+        await _kChannel.invokeMethod('getAll');
+    assert(fromSystem != null);
+    // Strip the flutter. prefix from the returned preferences.
+    final Map<String, Object> preferencesMap = <String, Object>{};
+    for (String key in fromSystem.keys) {
+      assert(key.startsWith(_prefix));
+      preferencesMap[key.substring(_prefix.length)] = fromSystem[key];
+    }
+    return preferencesMap;
+  }
+
   /// Initializes the shared preferences with mock values for testing.
   @visibleForTesting
   static void setMockInitialValues(Map<String, dynamic> values) {

packages/shared_preferences/pubspec.yaml

@@ -3,7 +3,7 @@ description: Flutter plugin for reading and writing simple key-value pairs.
   Wraps NSUserDefaults on iOS and SharedPreferences on Android.
 author: Flutter Team <[email protected]>
 homepage: https://github.com/flutter/plugins/tree/master/packages/shared_preferences
-version: 0.5.2+2
+version: 0.5.3
 
 flutter:
   plugin:

packages/shared_preferences/test/shared_preferences_test.dart

@@ -144,6 +144,17 @@ void main() {
       expect(log, <Matcher>[isMethodCall('clear', arguments: null)]);
     });
 
+    test('reloading', () async {
+      await preferences.setString('String', kTestValues['flutter.String']);
+      expect(preferences.getString('String'), kTestValues['flutter.String']);
+
+      SharedPreferences.setMockInitialValues(kTestValues2);
+      expect(preferences.getString('String'), kTestValues['flutter.String']);
+
+      await preferences.reload();
+      expect(preferences.getString('String'), kTestValues2['flutter.String']);
+    });
+
     test('mocking', () async {
       // TODO(amirh): remove this on when the invokeMethod update makes it to stable Flutter.
       // https://github.com/flutter/flutter/issues/26431