Problems while using Flutter Provider package

Question

I am creating a very simple app to practice flutter provider package. The app has a bulb which on click , should change it's background and the screen's background , using provider. But this doesnt seem to work. TBH this is a lot confusing

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

void main() => runApp(MainApp());

class Data extends ChangeNotifier{
  bool isOn = false;
  void toggle(){
    this.isOn = !this.isOn;
    notifyListeners();
    print("new value is $isOn");
  }
}

class MainApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return ChangeNotifierProvider<Data>(
      create: (context) => Data(),
      child: MaterialApp(
        home: Home(),
      ),
    );
  }
}

class Home extends StatefulWidget {
  @override
  _HomeState createState() => _HomeState();
}

class _HomeState extends State<Home> {

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(),
      backgroundColor: Provider.of<Data>(context).isOn ? Colors.yellow[100] : Colors.black,
      body: Center(
        child: Column(
          children: <Widget>[
            Stick(),
            Bulb(),
          ],
        ),
      ),
    );
  }
}

class Stick extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Container(
      height: 150,
      width: 40,
      color: Colors.brown,
    );
  }
}

class Bulb extends StatefulWidget {
  @override
  _BulbState createState() => _BulbState();
}

class _BulbState extends State<Bulb> {
  @override
  Widget build(BuildContext context) {
    return Container(
      height: 200,
      width: 250,
      decoration: BoxDecoration(
          borderRadius: BorderRadius.only(
              topLeft: Radius.circular(100),
              topRight: Radius.circular(100),
              bottomLeft: Radius.circular(30),
              bottomRight: Radius.circular(30)),
          color: Provider.of<Data>(context).isOn ? Colors.yellow : Colors.white,
      ),
      child: GestureDetector(
        onTap: (){
          Provider.of<Data>(context).toggle();
          setState(() {
          });
        },
      ),
    );
  }
}

The tree structure has a main app which houses a Home app , which houses 2 other widgets , a stick and a bulb inside a container. I am trying to update the background of bulb and the Home widget when the bulb is clicked. Bulb has a gesture detector Any kind of hint or help appreciated

Solution

Try to add listen: false to the provider call :

Provider.of<Data>(context, listen: false).toggle();

Comments

[Lakshay Dutta]

It worked ! Please explain how did that work ! Also do point out if there is anything wrong with the way I am using provider

[MickaelHrndz]

I don't know exactly why, but this is the doc on it : If [listen] is true, later value changes will trigger a new [State.build] to widgets, and [State.didChangeDependencies] for [StatefulWidget].

[Lakshay Dutta]

For anyone still looking for other ways to use provider, try Consumer<T> widget. it is better than calling Provider.of( ) each time