Flutter Trouble with multiselect checkboxes - data from Firestore - flutter

Question

The following code displays the items listed in my collection (Firestore)
I am attempting to create the ability to check any item(s) and then have those items store into a "Favorites" on the next screen.
Currently, the checkboxes are an all or nothing. Either all items are unchecked or checked once tapped.
class _SelectScreenState extends State<SelectScreen> {
bool _isChecked = false;
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(title: Text('Select Exercises')),
body: _buildBody(context),
);
}
Widget _buildBody(BuildContext context) {
return StreamBuilder<QuerySnapshot>(
stream: Firestore.instance.collection('exercises').snapshots(),
builder: (context, snapshot) {
if (!snapshot.hasData) return LinearProgressIndicator();
return _buildList(context, snapshot.data.documents);
},
);
}
Widget _buildList(BuildContext context, List<DocumentSnapshot> snapshot)
{
return ListView(
padding: const EdgeInsets.only(top: 20.0),
children: snapshot.map((data) => _buildListItem(context,
data)).toList(),
);
}
Widget _buildListItem(BuildContext context, DocumentSnapshot data) {
final record = Record.fromSnapshot(data);
return Padding(
key: ValueKey(record.name),
padding: const EdgeInsets.symmetric(horizontal: 16.0, vertical: 8.0),
child: Container(
decoration: BoxDecoration(
border: Border.all(color: Colors.grey),
borderRadius: BorderRadius.circular(5.0),
),
child: ListTile(
title: Text(record.name),
trailing: Checkbox(
value: _isChecked,
onChanged: (bool value) {
setState(() {
_isChecked = value;
});
},
)
),
),
);
}
}
class Record {
final String name;
final DocumentReference reference;
Record(this.name, this.reference);
Record.fromMap(Map<String, dynamic> map, {this.reference})
: assert(map['name'] != null),
name = map['name'];
Record.fromSnapshot(DocumentSnapshot snapshot)
: this.fromMap(snapshot.data, reference: snapshot.reference);
#override
String toString() => "Record<$name:>";
}

Answer 1

It is because you are making use of a single variable for all the checkboxes.
To fix that you could create a dedicated stateful widget, which would handle the state of each of the checkbox's separately from the rest.
So you could replace your ListTile with something like
Exercise(
title: record.name,
)
and then you could define the Exercise widget as follows
class Exercise extends StatefulWidget {
final String title;
Exercise({this.title});
#override
_ExerciseState createState() => _ExerciseState();
}
class _ExerciseState extends State<Exercise> {
bool selected = false;
#override
Widget build(BuildContext context) {
return ListTile(
title: Text(widget.title),
trailing: Checkbox(
value: selected,
onChanged: (bool val) {
setState(() {
selected = val;
});
}),
);
}
}
Here is a complete working example
import 'package:flutter/material.dart';
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
// This widget is the root of your application.
#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> {
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text(widget.title),
),
body: ListView(
children: <Widget>[
Exercise(
title: "Exercises 1",
),
Exercise(
title: "Exercises 2",
),
],
), // This trailing comma makes auto-formatting nicer for build methods.
);
}
}
class Exercise extends StatefulWidget {
final String title;
Exercise({this.title});
#override
_ExerciseState createState() => _ExerciseState();
}
class _ExerciseState extends State<Exercise> {
bool selected = false;
#override
Widget build(BuildContext context) {
return ListTile(
title: Text(widget.title),
trailing: Checkbox(
value: selected,
onChanged: (bool val) {
setState(() {
selected = val;
});
}),
);
}
}

Answer 2

Because you have a global variable _isChecked, this needs to be created with each listTile.
Try moving the variable
Widget _buildListItem(BuildContext context, DocumentSnapshot data) {
final record = Record.fromSnapshot(data);
bool _isChecked = false; //try moving it here
return Padding(
key: ValueKey(record.name),
padding: const EdgeInsets.symmetric(horizontal: 16.0, vertical: 8.0),
child: Container(
decoration: BoxDecoration(
border: Border.all(color: Colors.grey),
borderRadius: BorderRadius.circular(5.0),
),
child: ListTile(
title: Text(record.name),
trailing: Checkbox(
value: _isChecked,
onChanged: (bool value) {
setState(() {
_isChecked = value;
});
},
)
),
),
);
}