flutter putting data from api in expansion tile - flutter

Question

Hew guys , i got a small question .
im making a drawer that should have a titles and a neste titles so i use an expansion tile.
so the titles are displayed but when i press the arrow to open the nested titles it gives me an error.
i used future builder in the nested titles i think this is the problem the error gives me this
The following TypeErrorImpl was thrown building FutureBuilder<List<dynamic>>(dirty, state: _FutureBuilderState<List<dynamic>>#aeb31):
Unexpected null value.
this is my drawer
Drawer Image
this is my drawer code
import 'package:MyCima/Screens/drawer_title_page.dart';
import 'package:MyCima/models/drawer_shows_data_model.dart';
import 'package:MyCima/services/services.dart';
import 'package:flutter/material.dart';
import 'package:google_fonts/google_fonts.dart';
import '../constants.dart';
class FilmsDrawer extends StatefulWidget {
const FilmsDrawer({Key? key}) : super(key: key);
#override
_FilmsDrawerState createState() => _FilmsDrawerState();
}
class _FilmsDrawerState extends State<FilmsDrawer> {
final ServicesClass _services = ServicesClass();
late DrawerShowsDataModel _showsModelClass;
late Future drawerListData;
List nestedListNames = [];
#override
void initState() {
drawerListData = getDrawerList();
super.initState();
}
Future<List> getDrawerList() async {
return await _services.getFilms('menus');
}
#override
Widget build(BuildContext context) {
return Drawer(
elevation: 150,
semanticLabel: 'More Shows',
backgroundColor: PRIMARY,
child: Padding(
padding: const EdgeInsets.only(top: 24),
child: FutureBuilder(
future: drawerListData,
builder: (BuildContext context, AsyncSnapshot<dynamic> snapshot) {
switch (snapshot.connectionState) {
case ConnectionState.active:
case ConnectionState.waiting:
return const Center(
child: CircularProgressIndicator(),
);
case ConnectionState.done:
return Column(
children: [
Expanded(
flex: 5,
child: Column(
children: [
Expanded(
flex: 9,
child: Text(
'MyCima',
style: GoogleFonts.bevan(
fontSize: 16,
fontWeight: FontWeight.bold,
color: Colors.white,
),
),
),
const Expanded(
flex: 1,
child: Divider(
color: Colors.white,
indent: 64,
endIndent: 64,
),
),
],
),
),
Expanded(
flex: 95,
child: ListView.builder(
itemCount: snapshot.data.length,
itemBuilder: (context, index) {
_showsModelClass = DrawerShowsDataModel.fromJson(
snapshot.data[index]);
if (_showsModelClass.listChildren.length > 0) {
return ExpansionTile(
title: Text(
_showsModelClass.name,
style: const TextStyle(
color: Colors.white,
fontSize: 16,
fontWeight: FontWeight.bold,
),
),
children: [
getNestedTitles(index),
],
);
} else {
return Container(
alignment: Alignment.centerLeft,
padding: const EdgeInsets.all(8),
child: TextButton(
onPressed: () {
Navigator.push(
context,
MaterialPageRoute(
builder: (context) =>
const DrawerTitlePage()));
},
child: Text(
'${_showsModelClass.name}',
style: const TextStyle(
color: Colors.white,
fontWeight: FontWeight.bold,
),
),
),
);
}
}),
),
],
);
case ConnectionState.none:
return const Center(child: Text('No Connection'));
}
},
),
),
);
}
getNestedTitles(int index){
return FutureBuilder(
future: getDrawerList(),
builder: (BuildContext context, AsyncSnapshot<List<dynamic>> snapshot) {
return ListView.builder(
itemCount: snapshot.data![index]['children'].length,
itemBuilder: (BuildContext context, int index) {
_showsModelClass = DrawerShowsDataModel.fromNestedJson(snapshot.data![index]['children'][index]);
return TextButton(
onPressed: () {},
child: Text(
'${_showsModelClass.name}',
),
);
},
);
},
);
}
}

Answer 1

i found the answer
we need to make a list of widgets and add widgets on it then use it in the expansion
List<Widget> list = [];
List<Widget> getNestedTitles(int index) {
List<Widget> list = [];
drawerListData.then((value) {
for (var x in value[index]['children']) {
list.add(Padding(
padding: const EdgeInsets.all(8.0),
child: TextButton(
onPressed: () {
Navigator.push(
context,
MaterialPageRoute(
builder: (context) =>
const DrawerTitlePage()));
},
child: Text('${x['name']}',
style: const TextStyle(
color: Colors.white,
),),
),
));
}
});
return list;
}