flutter Listview itemextent - dart

Question

I'm struggling with the ListView.
My problem is that I've a Listview inside another Listview and the second Listview items height are not always the same. I want to get rid of the itemExtent and create an automatically height for the first Listview.
What I really want to acomplish is something like this:
#override
Widget build(BuildContext context) {
return
Column(
children: <Widget>[
TextField(),
Expanded(
child: ListView.builder(
key: new Key("ditisdekeyvoordelistview"),
itemBuilder: _makeMovieList,
padding: EdgeInsets.all(0.0),
itemCount: _movies.length,
itemExtent: 300.0,
),
),
],
);
}
//FIRST LIST
Widget _makeMovieList(BuildContext context, int index) {
return Container(
child: ListTile(
contentPadding: EdgeInsets.symmetric(horizontal: 20.0, vertical: 10.0),
leading: Container(
child: Column(mainAxisSize: MainAxisSize.max, children: <Widget>[
Image.network(
_movies[index].movieImage,
fit: BoxFit.cover,
width: 100.0,
)
])),
title: Text(
_movies[index].movieTitle,
),
subtitle: Column(
mainAxisAlignment: MainAxisAlignment.start,
crossAxisAlignment: CrossAxisAlignment.start,
children: <Widget>[
_makeStarRating(_movies[index].movieRating),
Text(_movies[index].movieDescription),
_makeCardDates(index)
],
),
),
);
}
//SECOND LIST
Widget _makeCardDates(int index) {
return Expanded(
child: ListView.builder(
physics: const NeverScrollableScrollPhysics(),
padding: EdgeInsets.all(0.0),
itemCount: _movies[index].dateTimeList.length,
itemBuilder: (context, indexx) {
return GestureDetector(
onTap: () {
print(_movies[index].dateTimeList[indexx].toString());
},
child: Card(
elevation: 8.0,
color: Color.fromRGBO(64, 75, 96, .9),
child: Column(
children: <Widget>[
Text(_movies[index].cinema),
Text(((dateFormatMovieHours
.format(_movies[index].dateTimeList[indexx]))
.toString())),
],
)));
},
itemExtent: 40.0,
),
);
}

Answer 1

Using itemExtent on a ListView isn't required, though ListView needs to have a finite height set for vertical scroll (default) and finite width is needed for horizontal scroll. Otherwise, the ListView will throw a "constraints are unbounded" error.
For your use case, you can either set height on the list items in the first ListView, or set height on the second ListView. However, if you'd like the second ListView to be non-scrollable and the list items in the first ListView will adapt dynamically, you can use a Column of Widgets similar to this sample.
import 'package:flutter/material.dart';
void main() {
runApp(MyApp());
}
class MyApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
primarySwatch: Colors.blue,
),
home: MyHomePage(title: 'Flutter Demo Home Page'),
);
}
}
class MyHomePage extends StatefulWidget {
MyHomePage({Key key, this.title}) : super(key: key);
final String title;
#override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
final items = [
'Apple',
'Banana',
'Carrot',
'Dog',
'Egg',
'Flower',
'Goat',
'Honey'
];
final subItems = ['1.00', '2.00', '3.00', '4.00'];
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text(widget.title),
),
body: Center(
child: firstList(),
),
);
}
firstList() {
return ListView.builder(
itemCount: items.length,
itemBuilder: (context, index) {
return Container(
padding: EdgeInsets.all(8.0),
child: Card(
child: Container(
color: Colors.lightBlue[50],
padding: EdgeInsets.all(16.0),
child: Row(
children: [
Expanded(
flex: 2,
child: Text('${items[index]}'),
),
Expanded(
flex: 1,
child: secondList(subItems),
),
],
),
),
),
);
},
);
}
secondList(List item) {
// Create List<Widget> for the second "List"
var subList = List<Widget>();
item.forEach((data) {
subList.add(
Card(
child: Container(
padding: EdgeInsets.all(16.0),
color: Colors.lightBlueAccent,
child: Text('$data'),
),
),
);
});
// Populate Column instead of ListView
return Column(
children: subList,
);
}
}