ExpansionPanel Issue

expansion_panel_issue

// instantiating the expansion panel with the below. Note the 500ms delay then adding another item.
//        body: (){
//        List<MinimalModel> items = [MinimalModel(),MinimalModel()];
//
//          Timer(Duration(milliseconds: 500), (){ 
//            items.add(MinimalModel()); //should be wrapped with setState
//          });
//
//        return ExpansionPanelIssue(items);
//      }()




import 'package:flutter/material.dart';

class MinimalModel {
  final selected = true;
}

class ExpansionPanelIssue extends StatefulWidget {
  static const String routeName = '/material/expansion_panels';

  final List<MinimalModel> minimalModel;

  ExpansionPanelIssue(List<MinimalModel> this.minimalModel);

  @override
  _ExpansionPanelIssue createState() {
    return _ExpansionPanelIssue(minimalModel);
  }
}

class _ExpansionPanelIssue extends State<ExpansionPanelIssue> {
  List<MinimalModel> _shoePairs;

  _ExpansionPanelIssue(this._shoePairs);

  @override
  Widget build(BuildContext context) {
    return SingleChildScrollView(
        child: SafeArea(
            top: false,
            bottom: false,
            child: Container(
              margin: const EdgeInsets.all(24.0),
              child: Theme(
                data: Theme.of(context).copyWith(cardColor: Colors.white),
                child: ExpansionPanelList(
                    expansionCallback: (int index, bool isExpanded) {
                      setState(() {});
                    },
                    children: _shoePairs.map<ExpansionPanel>(
                      (MinimalModel minimalModel) {
                        return ExpansionPanel(
                            isExpanded: minimalModel.selected,
                            headerBuilder:
                                (BuildContext context, bool isExpanded) {
                              return Container(child: Text('my header'));
                            },
                            body: Text('my body'));
                      },
                    ).toList()),
              ),
            )));
  }
}