Flutter: Create object stream from Hive box

user_8710943 0
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I am trying to access some user settings which are changed and accessed throughout the app. To do that, I am using Hive to retrieve user settings from a box. I would like to make that information accessible throughout the app by turning the UserSettings object retrieved from Hive.box('settings').get(userID) into a stream that will be fed into a StreamProvider.

How would I go about turning Hive.box('settings').get(userID) into a Stream?

Edit: Here is my code implementation so far:

local_database.dart

static Stream<UserSettings> get userSettings {
  return Hive.box('settings').watch(key: userID)?.map((boxEvent) {
    return boxEvent.value; // ========> value is always null from boxEvent
  });
}

static void saveUserSettings(UserSettings userPref) {
  Hive.box('settings').put(userID, userPref); 
}

main.dart

class Launch extends StatefulWidget {
  @override
  _LaunchState createState() => _LaunchState();
}

class _LaunchState extends State<Launch> {
  @override
  Widget build(BuildContext context) {
    return MultiProvider(
      providers: [
        StreamProvider<User>.value(value: AuthService.user),
        StreamProvider<UserSettings>.value(value: LocalDatabase.userSettings),
      ],
      child: MaterialApp(
        title: 'MyApp',
        home: AuthWrapper(),
      ),
    );
  }

settings.dart

class SettingsScreen extends StatefulWidget {
  @override
  _SettingsScreenState createState() => _SettingsScreenState();
}

class _SettingsScreenState extends State<SettingsScreen> {
  UserSettings _settings;

  @override
  Widget build(BuildContext context) {
    _settings = Provider.of<UserSettings>(context);

    print(_settings.useLightTheme); // =====> Always returns null

    return Scaffold(
      appBar: AppBar(title: 'Settings'),
      body: Container()
    ),
  }
}
flutter-hive dart flutter asynchronous
2 Answers

By this issue I can assume there is no way to get the initial values on watch, it's possible just with listenable:

ValueListenableBuilder(
  valueListenable: Hive.box('settings').listenable(),
  builder: (context, box, widget) {
    return Center(
      child: Switch(
        value: box.get('darkMode', defaultValue: false),
        onChanged: (val) => box.put('darkMode', val),
      ),
    );
  },
)
user_73850330

Use box.watch()

Next is a pseudo code just for example

Stream<User> listen() => box
      .watch(userID)
      .map(...) // somehow map your User
      .startWith(box.get(userID)); // initial value before any changes

PS If you will stuck in implementation - reach me in comments for help

PS 2: the startWith method is an extension provided by the rxdart package, so keep this in mind

user_120523090
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