how to accept multiple variables in result? - flutter

Question

I have an argument passed from one screen to the previous screen using pop().When I pass one variable, then everything is fine, but when I pass several, the application does not work.
How can I fix this and pass inputText and the value of two variables _privacy and _terms_of_use to me and output them? How can they be added to pop() and received in setState as a result?
My screen with arg:
class TextScreen extends StatefulWidget {
const TextScreen({Key? key}) : super(key: key);
#override
State<TextScreen> createState() => _TextScreenState();
}
class _TextScreenState extends State<TextScreen> {
// initial values for checkboxes
bool _privacy = false;
bool _termsOfUse = false;
// text controller for message input
TextEditingController textController = TextEditingController();
#override
void dispose() {
textController.dispose();
super.dispose();
}
void _getResult(BuildContext context) {
String inputText = textController.text;
Navigator.of(context).pop(inputText);
}
#override
Widget build(BuildContext context) {
void _onChangePrivacy(value) {
setState(() {
_privacy = value!;
});
}
void _onChangeTermsOfUse(value) {
setState(() {
_termsOfUse = value!;
});
}
return Scaffold(
appBar: AppBar(
title: const Text('Enter data'),
),
body: Padding(
padding: const EdgeInsets.symmetric(horizontal: 16.0),
child: Column(
crossAxisAlignment: CrossAxisAlignment.start,
mainAxisAlignment: MainAxisAlignment.center,
children: [
TextField(
controller: textController,
decoration: const InputDecoration(labelText: 'Message'),
),
const SizedBox(height: 20),
CheckboxListTile(
title: const Text('Privacy'),
controlAffinity: ListTileControlAffinity.leading,
value: _privacy,
onChanged: (value) {
_onChangePrivacy(value);
},
contentPadding: EdgeInsets.zero,
),
CheckboxListTile(
title: const Text('Terms of use'),
controlAffinity: ListTileControlAffinity.leading,
value: _termsOfUse,
onChanged: (value) {
_onChangeTermsOfUse(value);
},
contentPadding: EdgeInsets.zero,
),
ElevatedButton(
onPressed: () {
_getResult(context);
},
child: const Text('Display result'))
],
)),
);
}
}
My Result Screen:
class ResultScreen extends StatefulWidget {
#override
State<ResultScreen> createState() => _ResultScreenState();
}
class _ResultScreenState extends State<ResultScreen> {
String? _valueText = '';
#override
Widget build(BuildContext context) {
// navigation to next screen
void _navToNextScreen(BuildContext context) async {
final result = await Navigator.push(
context,
MaterialPageRoute(builder: (context) => const TextScreen()),
);
setState(() {
_valueText = result;
});
}
return Scaffold(
appBar: AppBar(
title: const Text('Results'),
),
body: Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: [
ElevatedButton(
onPressed: () {
_navToNextScreen(context);
},
child: const Text('Enter data')),
const SizedBox(height: 50),
Text('Message: $_valueText'),
const SizedBox(height: 20),
Text('Checkboxes: '),
],
)),
);
}
}

Answer 1

If we look at the implementation of the pop method it looks like this:
#optionalTypeArgs
static void pop<T extends Object?>(BuildContext context, [ T? result ]) {
Navigator.of(context).pop<T>(result);
}
This means we can optionally pass one generic object (T? result). In your case just passing a List containing multiple objects is the easiest solution.
The screen calling pop therefore could look like this:
Navigator.of(context).pop([inputText, inputText2]);
And your receiving screen could do something like this:
final results = await Navigator.push(
context,
MaterialPageRoute(builder: (context) => const TextScreen()),
);
var textOne = results[0];
var textTwo = results[1];
...

Answer 2

You can pass them in an array like that:
List<String> data = ['str1', 'str2', 'str3'];
Navigator.of(context).pop(data);
And Receive them like that:
List<String> result = await Navigator.push(
context,
MaterialPageRoute(builder: (context) => const TextScreen()),
);
setState(() {
_value1 = result[0];
_value2 = result[1];
_value3 = result[2];
});