Access List from statefulwidget to state - flutter

Question

I want to pass a List from screen 1 to screen 2 statefulwidget and want to add data to it.
List type Question,
class Question {
String questionText;
String answerText;
Question({this.questionText, this.answerText});
}
I passed the list to 2nd screen
class CardPage extends StatefulWidget {
final List<Question> questionBank;
CardPage({#required this.questionBank});
#override
......
I added the content to the list from state,
TextField(onChanged: (text) {question = text;}),
TextField(onChanged: (text) {answer = text;}),
FlatButton(
child: Text("Create"),
onPressed: () {setState(() {
questionBank.add(Question(questionText: question, answerText: answer));});
}
)
Bt I don't know how to connect the List in stateful widget to the state to access it. I know there is widget for it but don't know how to completely import the list to state with it.
Anyone help me

Answer 1

You can pass a function instead of list to your CardPage. It should be called when you create a new question. I think it is the most simple solution.
You CardPage should be like this:
class CardPage extends StatefulWidget {
final Function(Question) createQuestion;
CardPage({Key key, #required this.createQuestion}) : super(key: key);
#override
State<StatefulWidget> createState() => _CardPageState();
}
class _CardPageState extends State<CardPage> {
String _question = '';
String _answer = '';
#override
Widget build(BuildContext context) {
return Column(children: [
TextField(onChanged: (text) {
_question = text;
}),
TextField(onChanged: (text) {
_answer = text;
}),
FlatButton(
child: Text("Create"),
onPressed: () {
setState(() {
final question =
Question(questionText: _question, answerText: _answer);
widget.createQuestion(question);
});
})
]);
}
}
Question lists owner state should be like this:
class _FirstWidgetState extends State<FirstWidget> {
final List<Question> questionBank = [];
#override
Widget build(BuildContext context) {
return ...
CardPage(createQuestion: _createQuestion);
...
}
void _createQuestion(Question question) {
setState(() {
questionBank.add(question);
});
}
}

Answer 2

Try this
simple demo.
import 'package:flutter/material.dart';
void main() {
runApp(MaterialApp(
home: MyApp(),
));
}
class MyApp extends StatefulWidget {
#override
_State createState() => _State();
}
class _State extends State<MyApp> {
final List<String> names = <String>['apple', 'samsung', 'shirsh'];
TextEditingController nameController = TextEditingController();
void addItemToList(){
setState(() {
names.insert(0,nameController.text);
});
}
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text('Example'),
),
body: Column(
children: <Widget>[
Row(
children: [
Expanded(
flex: 5,
child: Padding(
padding: EdgeInsets.all(20),
child: TextField(
controller: nameController,
decoration: InputDecoration(
border: OutlineInputBorder(),
labelText: 'Contact Name',
),
),
),
),
Expanded(
flex: 2,
child: RaisedButton(
child: Text('Add Item'),
onPressed: () {
if(nameController.text.toString()!="")
addItemToList();
},
),
)
],
),
Expanded(
child: ListView.builder(
padding: const EdgeInsets.all(8),
itemCount: names.length,
itemBuilder: (BuildContext context, int index) {
return Container(
height: 50,
margin: EdgeInsets.all(2),
color: Colors.cyan,
child: Center(
child: Text('${names[index]}',
style: TextStyle(fontSize: 18),
)
),
);
}
)
)
]
)
);
}
}