Learning Flutter Redux - what is wrong with this code? - redux

Question

I am just getting into Flutter, Dart and Redux. Have followed a YouTube video to modify the default Flutter example to use Redux but its failing for me and I still have a hard time understanding exceptions and reacting to them effectively. Here is the code:
import 'package:flutter/material.dart';
import 'package:meta/meta.dart';
import 'package:redux/redux.dart';
import 'package:flutter_redux/flutter_redux.dart';
// following this youtube video: https://youtu.be/X8B-UzqEaWc
void main() => runApp(new MyApp());
#immutable
class AppState {
final int counter;
AppState(this.counter);
}
// actions
enum Actions { increment }
// pure function
AppState reducer(AppState prev, action) {
if(action == Actions.increment) {
return new AppState(prev.counter + 1);
}
return prev;
}
class MyApp extends StatelessWidget {
// This widget is the root of your application.
#override
Widget build(BuildContext context) {
return new MaterialApp(
title: 'Flutter Demo',
theme: new ThemeData.dark(),
home: new MyHomePage(),
);
}
}
class MyHomePage extends StatelessWidget {
final store = new Store(reducer, initialState: new AppState(0));
//print(store.state.counter); <----- Undefined class 'counter'.
#override
Widget build(BuildContext context) {
return new StoreProvider(
store: store,
child: new Scaffold(
appBar: new AppBar(
title: new Text("Flutter Redux"),
),
body: new Center(
child: new Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
new Text(
'You have pushed the button this many times:',
),
new StoreConnector(
converter: (store) => store.state.counter,
builder: (context, counter) => new Text(
"$counter",
style: Theme.of(context).textTheme.display1,
)
)
],
),
),
floatingActionButton: new StoreConnector<int, VoidCallback>(
converter: (store) {
return () => store.dispatch(Actions.increment);
},
builder: (context, callback) => new FloatingActionButton(
onPressed: callback,
tooltip: 'Increment',
child: new Icon(Icons.add),
),
)
),
);
}
}
So first of all, when I try to run this, I am getting an exception that states that "The following NoSuchMethodError was thrown building StoreConnector(dirty):
I/flutter (20662): The getter 'store' was called on null.". Secondary question is why the print method highlighted in the code is not recognizing counter getter? Thanks.

Answer 1

The problem was that I had "dart.previewDart2" set to true and I guess something might be screwed up in the latest preview build. Once I set the option to false, all worked good.
Details:
Got to File -> Preferences -> Settings.
Type 'dart" in the search box.
Once you find the setting dart.previewDart2, click on the pencil icon to the left of it and select "Copy to Settings".
On the right hand side in user settings, set the setting to true.