RxDart

About

RxDart is a reactive functional programming library for Google Dart, based on ReactiveX.
Google Dart comes with a very decent Streams API out-of-the-box; rather than attempting to provide an alternative to this API, RxDart adds functionality on top of it.

Version

Dart 1.0 is supported until release 0.15.x, version 0.16.x is no longer backwards compatible and requires the Dart SDK 2.0

How To Use RxDart

For Example: Reading the Konami Code

void main() {
  const konamiKeyCodes = const <int>[
    KeyCode.UP,
    KeyCode.UP,
    KeyCode.DOWN,
    KeyCode.DOWN,
    KeyCode.LEFT,
    KeyCode.RIGHT,
    KeyCode.LEFT,
    KeyCode.RIGHT,
    KeyCode.B,
    KeyCode.A];

  final result = querySelector('#result');
  final keyUp = Observable<KeyboardEvent>(document.onKeyUp);

  keyUp
    .map((event) => event.keyCode)
    .bufferCount(10, 1)
    .where((lastTenKeyCodes) => const IterableEquality<int>().equals(lastTenKeyCodes, konamiKeyCodes))
    .listen((_) => result.innerHtml = 'KONAMI!');
}

API Overview

Objects

• Observable
• PublishSubject
• BehaviorSubject
• ReplaySubject

Observable

RxDart's Observables extends the Stream class. This has two major implications:

• All methods defined on the Stream class exist on RxDart's Observables as well.
• All Observables can be passed to any API that expects a Dart Stream as an input.
• Additional important distinctions are documented as part of the Observable class

Finally, the Observable class & operators are simple wrappers around Stream and StreamTransformer classes. All underlying implementations can be used free of the Observable class, and are exposed in their own libraries. They are linked to below.

Instantiation

Generally speaking, creating a new Observable is either done by wrapping a Dart Stream using the top-level constructor new Observable(), or by calling a factory method on the Observable class. But to better support Dart's strong mode, combineLatest and zip have been pulled apart into fixed-length constructors. These methods are supplied as static methods, since Dart's factory methods don't support generic types.

Usage

var myObservable = new Observable(myStream);

Available Factory Methods

• concat / ConcatStream
• concatEager / ConcatEagerStream
• defer / DeferStream
• error / ErrorStream
• just
• merge / MergeStream
• never / NeverStream
• periodic
• race / RaceStream
• repeat / RepeatStream
• retry / RetryStream
• retryWhen / RetryWhenStream
• sequenceEqual / SequenceEqualStream
• switchLatest / SwitchLatestStream
• timer / TimerStream

Usage

var myObservable = new Observable.merge([myFirstStream, mySecondStream]);

Available Static Methods

• combineLatest / CombineLatestStream (combineLatest2, combineLatest... combineLatest9)
• forkJoin / ForkJoinStream (forkJoin2, forkJoin... forkJoin9)
• range / RangeStream
• tween / TweenStream
• zip / ZipStream (zip2, zip3, zip4, ..., zip9)

Usage

var myObservable = Observable.combineLatest3(
    myFirstStream, 
    mySecondStream, 
    myThirdStream, 
    (firstData, secondData, thirdData) => print("$firstData $secondData $thirdData"));

Transformations

Available Methods

• buffer / BufferStreamTransformer
• bufferCount / BufferStreamTransformer / onCount
• bufferTest / BufferStreamTransformer / onTest
• bufferTime / BufferStreamTransformer / onTime
• concatMap (alias for asyncExpand)
• concatWith
• debounce / DebounceStreamTransformer
• debounceTime / DebounceStreamTransformer
• delay / DelayStreamTransformer
• dematerialize / DematerializeStreamTransformer
• distinctUnique / DistinctUniqueStreamTransformer
• doOnCancel / DoStreamTransformer
• doOnData / DoStreamTransformer
• doOnDone / DoStreamTransformer
• doOnEach / DoStreamTransformer
• doOnError / DoStreamTransformer
• doOnListen / DoStreamTransformer
• doOnPause / DoStreamTransformer
• doOnResume / DoStreamTransformer
• exhaustMap / ExhaustMapStreamTransformer
• flatMap / FlatMapStreamTransformer
• flatMapIterable
• groupBy / GroupByStreamTransformer
• interval / IntervalStreamTransformer
• mapTo / MapToStreamTransformer
• materialize / MaterializeStreamTransformer
• mergeWith
• max / StreamMaxFuture
• min / StreamMinFuture
• onErrorResume / OnErrorResumeStreamTransformer
• onErrorResumeNext / OnErrorResumeStreamTransformer
• onErrorReturn / OnErrorResumeStreamTransformer
• onErrorReturnWith / OnErrorResumeStreamTransformer
• sample / SampleStreamTransformer
• sampleTime / SampleStreamTransformer
• scan / ScanStreamTransformer
• skipUntil / SkipUntilStreamTransformer
• startWith / StartWithStreamTransformer
• startWithMany / StartWithManyStreamTransformer
• switchMap / SwitchMapStreamTransformer
• takeUntil / TakeUntilStreamTransformer
• timeInterval / TimeIntervalStreamTransformer
• timestamp / TimestampStreamTransformer
• throttle / ThrottleStreamTransformer
• throttleTime / ThrottleStreamTransformer
• window / WindowStreamTransformer
• windowCount / WindowStreamTransformer / onCount
• windowTest / WindowStreamTransformer / onTest
• windowTime / WindowStreamTransformer / onTime
• withLatestFrom / WithLatestFromStreamTransformer
• zipWith

A full list of all methods and properties including those provided by the Dart Stream API (such as first, asyncMap, etc), can be seen by examining the DartDocs

Usage

var myObservable = new Observable(myStream)
    .bufferCount(5)
    .distinct();

Examples

Web and command-line examples can be found in the example folder.

Web Examples

In order to run the web examples, please follow these steps:

1. Clone this repo and enter the directory
2. Run pub get
3. Run pub run build_runner serve example
4. Navigate to http://localhost:8080/web/ in your browser

Command Line Examples

In order to run the command line example, please follow these steps:

1. Clone this repo and enter the directory
2. Run pub get
3. Run dart example/example.dart 10

Flutter Example

Install Flutter

In order to run the flutter example, you must have Flutter installed. For installation instructions, view the online documentation.

Run the app

1. Open up an Android Emulator, the iOS Simulator, or connect an appropriate mobile device for debugging.
2. Open up a terminal
3. cd into the example/flutter/github_search directory
4. Run flutter doctor to ensure you have all Flutter dependencies working.
5. Run flutter packages get
6. Run flutter run

Notable References

• Documentation on the Dart Stream class
• Tutorial on working with Streams in Dart
• ReactiveX (Rx)

Changelog

Refer to the Changelog to get all release notes.