rx_widgets 4.2.1

A package with stream based Flutter Widgets that facilitate an reactive programming style.

RxWidgets

About

A package with stream based Flutter Widgets that facilitate an reactive programming style.

Was built to be used especially in combination with RxDart and RxCommands.

If you have any ideas for additional stream based Widget, open an issue PRs are always welcome ;-)

Getting Started

Add to your pubspec.yaml dependencies to rx_widgets

Widgets Available

• RxElevatedButton
• RxText
• RxLoader
• RxSpinner
• WidgetSelector
• RxCommandBuilder
• ReactiveBuilder
• ReactiveWidget
• RxCommandHandlerMixin

RxElevatedButton

Creates a ElevatedButton that has an rxCommand instead of onPressed. It gets disabled if the command has canExecute:false or when isExecuting:true

An extended ElevatedButton where the onPressed is replaced with rxCommand and it gets disabled if the rxCommand has the canExecute set to false or when it is executing.

RxElevatedButton({
    Key key,
    // The RxCommand.
    this.rxCommand,
    this.child,
    // ... The rest of optional parameters
  });

RxText

A Text that takes in a Stream<String> and displays it. An example of usage can be when showing status message , or results of some requests.

errorBuilder is a method that is called when the stream receives an error. By default this method returns a Text containing the error.

placeHolderBuilder is a method that is called when the stream has no data. By default this method returns a CircularProgressIndicator. initialData parameter that can be used to provide a starting value, just like in StreamBuilder.

    RxText({
    // New parameters.
    @required Stream<String> stream,
    String initialData,
    this.errorBuilder,
    this.placeHolderBuilder,
    
    // Normal Text parameters.
    Key key,
    this.style,
    this.textAlign,
    this.textDirection,
    this.locale,
    this.softWrap,
    this.overflow,
    this.textScaleFactor,
    this.maxLines,
    this.semanticsLabel,
  });

RxSpinner

Spinner/Busy indicator that reacts on the output of a Stream<bool> it starts running as soon as a true value is received until the next falseis emitted. If the Spinner should replace another Widget while Spinning this widget can be passed as normal parameter. RxSpinner also adapts to the current or specified platform look. Needless to say that RxSpinner is ideal in combination with RxCommand's isExecuting Observable

busyEvents Stream<bool> that controls the activity of the Spinner. On receiving true it replaces the normal widget and starts running undtil it receives a falsevalue.

platform defines platform style of the Spinner. If this is null or not provided the style of the current platform will be used.

radius is the radius of the Spinner.

normal is a Widget that should be displayed while the Spinner is not active. If this is null a Container will be created instead. All other parameters please see https://docs.flutter.io/flutter/material/CircularProgressIndicator-class.html.

RxSpinner are ignored if the platform style is iOS.

RxSpinner({    
    Key key, 
    this.busyEvents, 
    this.platform, 
    this.radius = 20.0,  
    this.backgroundColor,
    this.value,
    this.valueColor,
    this.strokeWidth: 4.0,
    this.normal});         

RxLoader

RxSpinner is great for simple Applications where you just want to show or hide a Spinner. But often especially when loading data you want to deal with errors and show an alternative Widget if no data arrived. Since RxCommand offers not only three separate Observables for state changes and results but is also an Observable<CommandResult<T> itself that emits CommandResult that bundle all state and data in one Object RxLoaderleverage this to support the Flutter update mechanic better.

busyEvents Stream<bool> that controls the activity of the Spinner. On receiving true it replaces the normal widget and starts running undtil it receives a falsevalue.

platform defines platorm style of the Spinner. If this is null or not provided the style of the current platform will be used.

radius radius of the Spinner.

dataBuilder Builder that will be called as soon as an event with data is received. It will get passed the data feeld of the CommandResult.

placeHolderBuilder Builder that will be called as soon as an event with data==null is received.

errorBuilder Builder that will be called as soon as an event with an error is received. It will get passed the error feeld of the CommandResult.

All other parameters please see https://docs.flutter.io/flutter/material/CircularProgressIndicator-class.html. RxLoader are ignored if the platform style is iOS.

RxLoader({
    Key key 
    this.commandResults, 
    this.platform, 
    this.radius = 20.0,  
    this.backgroundColor,
    this.value,
    this.valueColor,
    this.strokeWidth: 4.0,
    this.dataBuilder, 
    this.placeHolderBuilder, 
    this.errorBuilder,
});

WidgetSelector

WidgetSelectoris a convenience class that will return one of two Widgets based on the output of a Stream<bool> This is pretty handy if you want to react to state change like enable/disable in you ViewModel and update the View accordingly.

If you don't need builders for the alternative child widgets this class offers a more concise expression than WidgetBuilderSelector

buildEvents Stream<bool>that signals that the this Widget should be updated.

onTrue Widget that should be returned if an item with value true is received.

onFalse Widget that should be returned if an item with value true is received.

errorBuilder Builder that will be called as soon as an event with an error is received. It will get passed the error feeld of the CommandResult.

placeHolderBuilder Builder that will be called as soon as an event with data==null is received.

initialData can be used to provide an initial value just as it does in StreamBuilder.

  WidgetSelector(
      {Key key,
      Stream<bool> buildEvents,
      this.onTrue,
      this.onFalse,
      this.errorBuilder,
      this.placeHolderBuilder,
      bool initialValue,
      });

WidgetSelector Example

This is an example where it is used to enable/disable a Button

WidgetSelector(
      buildEvents: myStream,
      onTrue: ElevatedButton(
          child: Text("Update"),
          onPressed: () {
            // Action
          }),
      onFalse: ElevatedButton(
        child: Text("Please Wait"),
        onPressed: null,
      ),
    );

WidgetBuilderSelector

Like WidgetSelector but instead return Widgets it executes one of two provided builder functions. In comparison to WidgetSelector this is best used if the alternative child widgets are large so that you don't want to have them always created without using them.

RxCommandBuilder

If you are working with RxCommands this is a special Builder that lets you define different builder for the different states an RxCommand can issue. If you don't specify one of the builders it will create a Container for that state.

commandResults Stream<bool> .Stream<CommandResult<T>> or a RxCommand<T> that issues CommandResults

busyBuilder Builder that will be called as soon as an event with isExecuting==true.

dataBuilder Builder that will be called as soon as an event with data is received. It will get passed the data feeld of the CommandResult. It will get passed the data feeld of the CommandResult.

placeHolderBuilder Builder that will be called as soon as an event with data==null is received. If this is null a Container will be created instead.

errorBuilder Builder that will be called as soon as an event with an error is received. It will get passed the error feeld of the CommandResult.

const RxCommandBuilder({Key key,
        this.commandResults, 
        this.platform, 
        this.radius = 20.0,  
        this.backgroundColor,
        this.value,
        this.valueColor,
        this.strokeWidth: 4.0,
        this.busyBuilder,
        this.dataBuilder, 
        this.placeHolderBuilder, 
        this.errorBuilder,
        }) 

ReactiveBuilder

Widget built to encapsulate StreamBuilder.

stream Stream<T> that controls the widget.

initialData can be used to provide an initial value just as it does in StreamBuilder.

builder lis a method that will be cal when the stream receive data.

placeHolderBuilder is a method that will be cal when the stream is initialized without data or when receive a null data. By default this method returns a CircularProgressIndicator.

errorBuilder is a method that will be call when the stream receive a error. By default this method returns a Text containing the error.

const ReactiveBuilder({
    Key key,
    @required Stream<T> stream,
    T initialData,
    @required this.builder,
    this.placeHolderBuilder,
    this.errorBuilder,
  })

ReactiveBuilder Example

class Animal {
  String name;
  int age;
}

class Example extends StatelessWidget {
  final Stream<Animal> stream;

  Example(this.stream);

  @override
  Widget build(BuildContext context) {
    return ReactiveBuilder<Animal>(
      stream: stream,
      builder: (BuildContext context, data) {
        return ListTile(
          title: Text(data.name),
          subtitle: Text("${data.age}"),
        );
      },
    );
  }
}

ReactiveWidget

Widget built to encapsulate StreamBuilder.

Similar to ReactiveBuilder but doesn't require BuiltContext in its parameters

stream Stream<T> that controls the widget.

initialData can be used to provide an initial value just as it does in StreamBuilder.

widget lis a method that will be cal when the stream receive data.

placeHolderWidget is a method that will be cal when the stream is initialized without data or when receive a null data. By default this method returns a CircularProgressIndicator.

errorWidget is a method that will be call when the stream receive a error. By default this method returns a Text containing the error.

ReactiveWidget Example

class Animal {
  String name;
  int age;
}

class Example extends StatelessWidget {
  final Stream<Animal> stream;

  Example(this.stream);

  @override
  Widget build(BuildContext context) {
    return ReactiveBuilder<Animal>(
      stream: stream,
      builder: (data) {
        return ListTile(
          title: Text(data.name),
          subtitle: Text("${data.age}"),
        );
      },
    );
  }
}

RxCommandHandlerMixin

Adds ability to listen om RxCommand events inside Stateless and Stateful Widgets.

Add RxCommandHandlerMixin to your Stateless Widget or
RxCommandStatefulHandlerMixin to your Stateful Widget and override RxCommandListener get commandListener.

It will add your widget to get an ability to listen for events from command and make actions specified in RxCommandListener when its streams fire events.

Mixin will take care of RxCommandListener init dispose. This way you can keep your widget stateless. Or if it is already stateful - don't need to write code for that.

RxCommandHandlerMixin Example

class CommandWidget extends StatelessWidget with RxCommandHandlerMixin {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: ElevatedButton(
          child: Text('Test Command'),
          onPressed: _command,
        ),
      ),
    );
  }

  @override
  RxCommandListener get commandListener => RxCommandListener<void, DateTime>(
    _command,
    onValue: (value) => print('received value: $value'),
    onError: (error) => print('error fired: $error'),
  );
}

final _command = RxCommand.createSyncNoParam<DateTime>(() {
  final now = DateTime.now();
  if (now.millisecondsSinceEpoch.isEven) {
    return now;
  } else {
    throw Exception('MillisecondsSinceEpoch is not even');
  }
});