redux.dart

Build Status

Redux for Dart using generics for typed State. It includes a rich ecosystem of Docs, Middleware, Dev Tools and can be combined with Flutter using the flutter_redux package.

Redux 3.0.0 Migration & Dart 2 support

In order to support Dart 2, some of the APIs needed to change. The good news: This actually simplifies Redux! The bad news: you may need to update your projects.

  • Change ReducerBinding to TypedReducer
  • Remove combineTypedReducer. Use combineReducers with a combination of normal reducers and/or TypedReducers.
  • Change MiddlewareBinding to TypedMiddleware.
  • Remove combineTypedMiddleware -- no longer needed! Just create a normal List<Middleware<State>>!

Usage

import 'package:redux/redux.dart';

// Create typed actions. You will dispatch these in order to
// update the state of your application.
enum Actions {
  increment,
  decrement,
}

// Create a Reducer. A reducer is a pure function that takes the 
// current State (int) and the Action that was dispatched. It should
// combine the two into a new state without mutating the state passed
// in! After the state is updated, the store will emit the update to 
// the `onChange` stream.
// 
// Because reducers are pure functions, they should not perform any 
// side-effects, such as making an HTTP request or logging messages
// to a console. For that, use Middleware.
int counterReducer(int state, action) {
  if (action == Actions.increment) {
    return state + 1;
  } else if (action == Actions.decrement) {
    return state - 1;
  }
  
  return state;
}

// A piece of middleware that will log all actions with a timestamp
// to your console!
// 
// Note, this is just an example of how to write your own Middleware.
// See the redux_logging package on pub for a pre-built logging 
// middleware.
loggingMiddleware(Store<int> store, action, NextDispatcher next) {
  print('${new DateTime.now()}: $action');

  next(action);
}

main() {
  // Create the store with our Reducer and Middleware
  final store = new Store<int>(
    counterReducer, 
    initialState: 0, 
    middleware: [loggingMiddleware],
  );

  // Render our State right away
  render(store.state);
  
  // Listen to store changes, and re-render when the state is updated
  store.onChange.listen(render);

  // Attach a click handler to a button. When clicked, the `INCREMENT` action
  // will be dispatched. It will then run through the reducer, updating the 
  // state.
  //
  // After the state changes, the html will be re-rendered by our `onChange`
  // listener above. 
  querySelector('#increment').onClick.listen((_) {
    store.dispatch(Actions.increment);
  });
}

render(int state) {
  querySelector('#value').innerHtml = '${state}';
}

Docs

  • Motivation and Principles - Learn why Redux might make sense for your app and the principles behind it.
  • Basics - Introduction to the core concepts in Redux
  • Combining Reducers - combineReducers works a bit differently in Dart than it does in JS. Learn why, and how to combine reducers in a type-safe way!
  • Async with Middleware - Learn how to make async calls, such as to a web service or local database, with Redux.
  • API Documentation - Rich documentation included in the source code and generated by DartDoc.

Flutter Examples

Web Examples

See the example/ directory for a few simple examples of the basics of Redux.

To launch the examples in your browser:

  1. Run pub serve example from this directory
  2. Open http://localhost:8080

Middleware

  • redux_logging - Connects a Logger to a Store, and can print out actions as they're dispatched to your console.
  • redux_thunk - Allows you to dispatch functions that perform async work as actions.
  • redux_future - For handling Dart Futures that are dispatched as Actions.
  • redux_epics - Middleware that allows you to work with Dart Streams of Actions to perform async work.

Dev Tools

The redux_dev_tools library allows you to create a DevToolsStore during dev mode in place of a normal Redux Store.

This DevToolsStore will act exactly like a normal Store at first. However, it will also allow you to travel back and forth throughout the States of your app or recompute the State of your app by replaying all actions through your reducers. This works perfectly with Hot Reloading!

You can combine the DevToolsStore with your own UI to travel in time, or use one of the existing options for the platform you're working with:

Additional Utilities

  • reselect - Efficiently derive data from your Redux Store with memoized functions.

Libraries

redux