Efficiently Managing Data in Flutter Apps with Redux

The Problem with Traditional Data Management

In a typical Flutter app, data is passed from one widget to another through the constructor. This can lead to a long chain of data transfer through widgets that don’t need the data, resulting in boilerplate code and potential performance issues. When a change occurs in any of its child widgets, the entire widget tree rebuilds, affecting the performance of the application.

The Solution: Redux

Redux is a state management architecture library that distributes data across widgets in a repetitive manner. It manages the state of an application through a unidirectional flow of data. With Redux, you can structure your application so that the state is extracted in a centrally-located store, accessible by any widget that requires the data.

Key Concepts in Redux

• Store: The central location where the application state exists.
• Reducer: A function that updates the store with a new state.
• Actions: Objects that determine what event is performed on the state.
• Middleware: A Redux component that processes an action before the reducer function receives it.

How Redux Works

When a widget wants to make a change to the state using an action, it uses the dispatch method of the store to communicate to the state about this action. The store then invokes the action, and the reducer function processes the action and updates the state. The updated state is reflected in the UI, triggering the logic that rebuilds the UI within the StoreConnector widget.

store.dispatch(GetTimeAction('location'));
// The GetTimeAction is processed by the middleware and then the reducer
// The reducer updates the state with the new time data
// The UI is rebuilt with the updated state

Implementing Redux in Flutter

To implement Redux in Flutter, you’ll need to add the following dependencies to your pubspec.yaml file:

dependencies:
  flutter:
    sdk: flutter
  redux: ^4.0.0
  flutter_redux: ^0.7.0
  flutterreduxdev_tools: ^0.3.0
  redux_thunk: ^2.3.0
  http: ^0.13.3
  Intl: ^0.17.0

Building a Basic Redux Application in Flutter

Let’s build a basic application that implements Redux in Flutter. Our demo application will contain an interface with a button that fetches the current time of a location on every click. We’ll use the World Time API to fetch the time and location data needed to enable this feature.

// Create an action to get the time
class GetTimeAction {
  final String location;

  GetTimeAction(this.location);
}

// Create a reducer to update the state
TimeState reducer(TimeState state, action) {
  if (action is GetTimeAction) {
    // Update the state with the new time data
    return TimeState(time: 'new time data');
  }
  return state;
}

// Create a middleware to process the action
class Middleware {
  Future processAction(Store store, action, NextDispatcher next) async {
    if (action is GetTimeAction) {
      // Make an API call to fetch the time data
      final response = await http.get(Uri.parse('https://worldtimeapi.org/api/timezone/${action.location}'));
      // Update the state with the new time data
      store.dispatch(GetTimeActionSuccess(response.body));
    }
    next(action);
  }
}

// Create a widget to display the time
class TimeDisplay extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return StoreConnector<timestate, string="">(
      converter: (store) => store.state.time,
      builder: (context, time) {
        return Text(time);
      },
    );
  }
}</timestate,>

By following these steps and implementing Redux in your Flutter app, you can efficiently manage data and build a scalable and maintainable application.