After rebuild callbacks

[brianegan]

This adds two callbacks to the StoreConnector and StoreBuilder:

• onInitialBuild -- Called after the Widget is built the first time
• onDidChange -- Called after the Widget is rebuilt when the ViewModel changes (if you use distinct and the ViewModel does not change, this will not be invoked).

Fixes #47

[codecov]

Codecov Report

Merging #55 into master will increase coverage by 0.17%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master      #55      +/-   ##
==========================================
+ Coverage   98.59%   98.76%   +0.17%     
==========================================
  Files           1        1              
  Lines          71       81      +10     
==========================================
+ Hits           70       80      +10     
  Misses          1        1

Impacted Files	Coverage Δ
lib/flutter_redux.dart	98.76% <100%> (+0.17%)	⬆️

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[kitoko552]

thank you for your changes:)
it seems to have no problem and looks great!

[brianegan]

Sounds good! I'm currently traveling and will merge this up when I'm back in action early next week :)

If you need this right away, please consider pointing your pubspec to this branch until I can publish a new version!

[AlexandreRoba]

Hi Brian,

Thanks for the quick implementation :).
I tried to use it but i'm having an exception when using the Navigator inside onDidChange.

flutter: ══╡ EXCEPTION CAUGHT BY SCHEDULER LIBRARY ╞═════════════════════════════════════════════════════════
flutter: The following assertion was thrown during a scheduler callback:
flutter: Looking up a deactivated widget's ancestor is unsafe.
flutter: At this point the state of the widget's element tree is no longer stable. To safely refer to a
flutter: widget's ancestor in its dispose() method, save a reference to the ancestor by calling
flutter: inheritFromWidgetOfExactType() in the widget's didChangeDependencies() method.
flutter:
flutter: When the exception was thrown, this was the stack:
flutter: #0      Element._debugCheckStateIsActiveForAncestorLookup.<anonymous closure> (package:flutter/src/widgets/framework.dart:3203:9)
flutter: #1      Element._debugCheckStateIsActiveForAncestorLookup (package:flutter/src/widgets/framework.dart:3212:6)
flutter: #2      Element.ancestorStateOfType (package:flutter/src/widgets/framework.dart:3254:12)
flutter: #3      Navigator.of (package:flutter/src/widgets/navigator.dart:1176:19)
flutter: #4      Navigator.pushReplacementNamed (package:flutter/src/widgets/navigator.dart:684:22)
flutter: #5      SplashScreen.build.<anonymous closure> (package:sweetnest_app/containers/splash_screen.dart:23:21)
flutter: #6      _StoreStreamListenerState._init.<anonymous closure>.<anonymous closure> (package:flutter_redux/flutter_redux.dart)
flutter: #7      _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding._invokeFrameCallback (package:flutter/src/scheduler/binding.dart:990:15)
flutter: #8      _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding.handleDrawFrame (package:flutter/src/scheduler/binding.dart:938:9)
flutter: #9      _WidgetsFlutterBinding&BindingBase&GestureBinding&ServicesBinding&SchedulerBinding._handleDrawFrame (package:flutter/src/scheduler/binding.dart:842:5)
flutter: #10     _invoke (dart:ui/hooks.dart:120:13)
flutter: #11     _drawFrame (dart:ui/hooks.dart:109:3)
flutter: ════════════════════════════════════════════════════════════════════════════════════════════════════
flutter: Another exception was thrown: Looking up a deactivated widget's ancestor is unsafe.

the exception is raised on a container splash screen. It's store connector looks like that:

  @override
  Widget build(BuildContext context) {
    return StoreConnector<AppState, _ViewModel>(
      converter: _ViewModel.fromStore,
      onInitialBuild: (_ViewModel vm) {
        vm.onLaunchStarted();
      },
      onDidChange: (_ViewModel vm){
        if(vm.initializationCompleted)
          Navigator.pushReplacementNamed(context, 'home');
      },
      builder:...
}

onLauchStarted dispatch an action that is captured by a middleware that perform all necessary initialization. Once the middleware is complete it dispatch an action that will be reduce to set a initializationCompleted flag on the appState.
On onDidChange I check for this state and if its true I navigate to the home screen...

The flow works but I have this nasty exception... Any idea?

thanks ,

Alex

[AlexandreRoba]

I moved the conditional routing to onWillChange and the exception is no more.
I guess we should not make use of the context on the onDidChange?

[brianegan]

Thanks for the feedback @AlexandreRoba -- I'll add that to the docs.