Question 76116 in Flutter Question posted in
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How can parent widget gets information from it's children widget in Flutter?

I create a parent page contains a list about custom widgets, the list is variable so I can add or decrease the number of these custom widgets immediately.

The custom widgets are contained by

  List<FoodContainer> _foods = [];

in parent page.

The custom widget looks like:

class FoodContainer extends StatefulWidget {
  const FoodContainer({
    Key? key,
  }) : super(key: key);

  @override
  _FoodContainerState createState() => _FoodContainerState();
}

class _FoodContainerState extends State<FoodContainer> {

  var _result;
  
  @override
  Widget build(BuildContext context) {
    return Container(
      child :TextField(
        onSubmitted: (String s){
          setState(() {
            _result = Func(s);
          });
        },
      ),
    );
  }
}

Now I want to get the value of _result in every child widget,how can I get them?

I tried to do like this:

class FoodContainer extends StatefulWidget {
  const FoodContainer({
    Key? key,
    required this.foodTextControl,
  }) : super(key: key);
  final TextEditingController foodTextControl;

The widget.foodTextControl.text can be read in parent page, but the Func(s) is a web request, I don’t want to request twice.

Tags:

2

Answers


  1. Chosen as BEST ANSWER
    0

    Thanks for Aswanath C K,I created a simple custom controller to get the child widget info.

    class TestController extends ValueNotifier<String>{
  TestController({ String? text }) : super(text == null ? "None" : text);

  TestController.fromValue(String? value)
  :assert(
      value == null,'Now:${value}'
    ),
    super(value ?? "None");

  String get text => value;

  set text(String newText) {
    value = newText;
  }

  @override
  set value(String newValue) {
    super.value = newValue;
  }
}

    When the _result changes,make

    widget.testController.text = _result;

    Now it's finished.


  2. 0

    If you want the _result of all the children (FoodContainers) to the parent (ListView.builder).Then you can use

    final ValueChanged<String> onChanged;

    and when the onSubmitted is called you can use this like:

    widget.onChanged(_result);

    And on the parent(Listview) you can get the access by:

    FoodContainer(
onChanged: (val){
   print(val);
   }

    I hope this will resolve your issue.

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