FoldingCellWithModel

main.dart

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

void main() => runApp(MaterialApp(

    home: SafeArea(
        child: Scaffold(body: Material(child: FoldingCellListViewDemo())))));

class DemoModel {
  String title, subtitle;

  DemoModel(this.title, this.subtitle);
}


/// Example 2 folding cell inside [ListView]
class FoldingCellListViewDemo extends StatelessWidget {
  final List<DemoModel> txtList = [
    DemoModel('title 1', 'Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry. Lorem Ipsum has been the industry. Lorem Ipsum has been the industry.'),
    DemoModel('title 2', 'subtitle 2'),
    DemoModel('title 3', 'subtitle 3'),
    DemoModel('title 4', 'subtitle 4'),
  ];

  @override
  Widget build(BuildContext context) {
    return Container(
      color: Color(0xFF2e282a),
      child: ListView.builder(
          itemCount: txtList.length,
          itemBuilder: (context, index) {
            DemoModel model = txtList[index];
            return SimpleFoldingCell(
                frontWidget: _buildFrontWidget(model),
                innerTopWidget: _buildInnerTopWidget(model),
                innerBottomWidget: _buildInnerBottomWidget(index),
                cellSize: Size(MediaQuery.of(context).size.width, 125),
                padding: EdgeInsets.all(15),
                animationDuration: Duration(milliseconds: 300),
                borderRadius: 10,
                onOpen: () => print('$index cell opened'),
                onClose: () => print('$index cell closed'));
          }),
    );
  }

  Widget _buildFrontWidget(DemoModel model) {
    return Builder(
      builder: (BuildContext context) {
        return Container(
            color: Color(0xFFffcd3c),
            alignment: Alignment.center,
            child: Column(
              mainAxisAlignment: MainAxisAlignment.center,
              children: <Widget>[
                Text("${model.title}",
                    style: TextStyle(
                        color: Color(0xFF2e282a),
                        fontFamily: 'OpenSans',
                        fontSize: 20.0,
                        fontWeight: FontWeight.w800)),
                FlatButton(
                  onPressed: () {
                    SimpleFoldingCellState foldingCellState =
                    context.ancestorStateOfType(
                        TypeMatcher<SimpleFoldingCellState>());
                    foldingCellState?.toggleFold();
                  },
                  child: Text(
                    "Open",
                  ),
                  textColor: Colors.white,
                  color: Colors.indigoAccent,
                  splashColor: Colors.white.withOpacity(0.5),
                )
              ],
            ));
      },
    );
  }

  Widget _buildInnerTopWidget(DemoModel model) {
    return Container(
        color: Color(0xFFff9234),
        alignment: Alignment.center,
        child: Text("${model.subtitle}",
            style: TextStyle(
                color: Color(0xFF2e282a),
                fontFamily: 'OpenSans',
                fontSize: 14.0,
                fontWeight: FontWeight.w400)));
  }

  Widget _buildInnerBottomWidget(int index) {
    return Builder(builder: (context) {
      return Container(
        color: Color(0xFFecf2f9),
        alignment: Alignment.bottomCenter,
        child: Padding(
          padding: EdgeInsets.only(bottom: 10),
          child: FlatButton(
            onPressed: () {
              SimpleFoldingCellState foldingCellState = context
                  .ancestorStateOfType(TypeMatcher<SimpleFoldingCellState>());
              foldingCellState?.toggleFold();
            },
            child: Text(
              "Close",
            ),
            textColor: Colors.white,
            color: Colors.indigoAccent,
            splashColor: Colors.white.withOpacity(0.5),
          ),
        ),
      );
    });
  }
}

Repo link is broken, try to create repo of your complete code so I can run that in one go only