BuildContext InheritedWidget becomes null within a ScopedModel return object about scoped_model HOT 3 CLOSED

class MyHomePage extends StatelessWidget {
  final String title;

  const MyHomePage({Key key, this.title}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Broken Button'),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: () {
          // This will fail, because we're referencing a context that doesn't include the Scaffold
          Scaffold.of(context).showSnackBar(SnackBar(content: Text('Hi')));
        },
        child: Icon(Icons.add),
      ),
    );
  }
}

class MyHomePage extends StatelessWidget {
  final String title;

  const MyHomePage({Key key, this.title}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Broken Button'),
      ),
      floatingActionButton: new MyButton(),
    );
  }
}

class MyButton extends StatelessWidget {
  const MyButton({
    Key key,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return FloatingActionButton(
      onPressed: () {
        Scaffold.of(context).showSnackBar(SnackBar(content: Text('Hi')));
      },
      child: Icon(Icons.add),
    );
  }
}

import 'package:flutter/material.dart';
import 'package:scoped_model/scoped_model.dart';

class AppConfig extends InheritedWidget {
  final String apiURL;

  AppConfig({
    @required this.apiURL,
    @required Widget child,
  }) : super(child: child);

  static AppConfig of(BuildContext context) {
    return context.inheritFromWidgetOfExactType(AppConfig);
  }

  @override
  bool updateShouldNotify(InheritedWidget oldWidget) => false;
}

void main() {
  runApp(AppConfig(
    apiURL: 'hello',
    child: MyApp(
      model: CounterModel(),
    ),
  ));
}

class MyApp extends StatelessWidget {
  final CounterModel model;

  const MyApp({Key key, @required this.model}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    // At the top level of our app, we'll, create a ScopedModel Widget. This
    // will provide the CounterModel to all children in the app that request it
    // using a ScopedModelDescendant.
    return ScopedModel<CounterModel>(
      model: model,
      child: MaterialApp(
        title: 'Scoped Model Demo',
        home: CounterHome('Scoped Model Demo'),
      ),
    );
  }
}

// Start by creating a class that has a counter and a method to increment it.
//
// Note: It must extend from Model.
class CounterModel extends Model {
  int _counter = 0;

  int get counter => _counter;

  void increment() {
    // First, increment the counter
    _counter++;

    // Then notify all the listeners.
    notifyListeners();
  }
}

class CounterHome extends StatelessWidget {
  final String title;

  CounterHome(this.title);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(title),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            Text('You have pushed the button this many times:'),
            // Create a ScopedModelDescendant. This widget will get the
            // CounterModel from the nearest parent ScopedModel<CounterModel>.
            // It will hand that CounterModel to our builder method, and
            // rebuild any time the CounterModel changes (i.e. after we
            // `notifyListeners` in the Model).
            ScopedModelDescendant<CounterModel>(
              builder: (context, child, model) {
                return Text(
                  '${model.counter}, Api URL: ${AppConfig.of(context).apiURL}',
                );
              },
            ),
          ],
        ),
      ),
      // Use the ScopedModelDescendant again in order to use the increment
      // method from the CounterModel
      floatingActionButton: ScopedModelDescendant<CounterModel>(
        builder: (context, child, model) {
          return FloatingActionButton(
            onPressed: model.increment,
            tooltip: 'Increment',
            child: Icon(Icons.add),
          );
        },
      ),
    );
  }
}