从 Flutter 中的父小部件访问 const 子小部件变量

Question

I want to access child widget variable value in parent widget whereas child widget is a const widget which does not allow me to use GlobalKey for const child widget.

My question is how can I access child widget without GlobalKey. Here is my code snippet:

 class ParentWidget extends StatefulWidget { @override State<StatefulWidget> createState() { // TODO: implement createState return ParentWidgetState(); } } class ParentWidgetState extends State<ParentWidget> { @override Widget build(BuildContext context) { return Container( child: const LeftSidePanel(),); } } class LeftSidePanel extends StatefulWidget { @override State<StatefulWidget> createState() { // TODO: implement createState return LeftPanelWidgetState(); } const LeftSidePanel( ); } class LeftSidePanelState extends State<LeftSidePanel> { }

Anyone there to answer my query please. Thanks

Answer 1

In this example none of widgets have to be Statefull ( try to use as few statefull widgets as you can)

import 'package:flutter/material.dart';

class ParentWidget extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Container(
      child: ChildWidget(
        getWidgetTextCallback: (someParameter) {
          print(someParameter);
          // here you can have the value from the Child widget use it wisely
        },
      ),
    );
  }
}

class ChildWidget extends StatelessWidget {
  final widgetText = 'widgetText';

  final Function(String) getWidgetTextCallback;

  const ChildWidget({required this.getWidgetTextCallback});
  
  @override
  Widget build(BuildContext context) {
    return Column(
      children: [
        Text(widgetText),
        ElevatedButton(
          onPressed:
              getWidgetTextCallback(widgetText),
          child: Text(widgetText),
        )
      ],
    );
  }
}