Not able to change a value in one page with respect to the value from another page in flutter - flutter

Question

i want to change the indexvalue (pictogramindex) of one page when we click nextbutton on another screen.I will explain briefly , I have 2 screens in my scenario the first screen contains an image and it's name , a textfield and nextbutton (i have provided a dummy data contains a list of image and it's names) the logic behind this is , when we complete the textfield box and click next button(after validate) the textfield value checks with the correctvalue which i was given in the dummy data and show it's synonym which also provided. when we click the next button we will go to another page which contains the correct answer(passed from first page) and a textfield in this the user can write about the correct answer ( validated) when click next button in this page (till this my applicationworks perfectly) i want to load the first page with it's index updated (+1) which i initialised as 0 (var pictogramindex=0). But in my case when coming back to first page the index is not updating it will automatically stores the initialised value. what i want is i want to update index on the first page when i click next button in the Second page .
my source code of first screen is shown here
class Pictogramscreen extends StatefulWidget {
final int length;
const Pictogramscreen({Key key, this.length}) : super(key: key);
#override
_PictogramscreenState createState() => _PictogramscreenState();
}
class _PictogramscreenState extends State<Pictogramscreen> {
#override
final _Key = GlobalKey<FormState>();
Color defaultcolor = Colors.blue[50];
Color trueColor = Colors.green;
Color falseColor = Colors.red;
Widget defcorrect = Text('');
var pictogramindex = 0;
TextEditingController usertitleInput = TextEditingController();
nextPictogram() {
setState(() {
pictogramindex++;
});
}
fillColor() {
setState(() {
usertitleInput.text == pictdata[pictogramindex]['pictcorrectword']
? defaultcolor = trueColor
: defaultcolor = falseColor;
});
}
correctText() {
setState(() {
usertitleInput.text == pictdata[pictogramindex]['pictcorrectword']
? defcorrect = Text(pictdata[pictogramindex]['pictsynonym'])
: defcorrect = Text(pictdata[pictogramindex]['pictcorrectword']);
});
}
reset() {
setState(() {
defaultcolor = Colors.blue[50];
defcorrect = Text('');
usertitleInput.clear();
});
}
void description(BuildContext ctx) {
Navigator.of(context).pushNamed('/user-description', arguments: {
'id': pictdata[pictogramindex]['pictid'],
'word': pictdata[pictogramindex]['pictcorrectword']
});
}
Widget build(BuildContext context) {
int length = pictdata.length;
return Scaffold(
body: pictogramindex < pictdata.length
? ListView(
children: <Widget>[
Container(
margin: EdgeInsets.only(top: 20),
padding: EdgeInsets.all(15),
child: Column(
crossAxisAlignment: CrossAxisAlignment.center,
children: <Widget>[
Card(
margin: EdgeInsets.only(top: 20),
child: Image.network(
pictdata[pictogramindex]['pictimg']),
),
SizedBox(
height: 10,
),
Text(
pictdata[pictogramindex]['pictword'],
style: TextStyle(
fontSize: 25,
),
),
SizedBox(
height: 10,
),
//Card(
//color: Colors.blue,
// child: TextField(
// decoration: InputDecoration.collapsed(
// hintText: 'type here'),
//textAlign: TextAlign.center,
// onSubmitted: (value) {
// usertitleInput = value;
// print(usertitleInput);
// },
// ),
//),
Form(
key: _Key,
child: TextFormField(
controller: usertitleInput,
validator: (usertitleInput) {
if (usertitleInput.isEmpty) {
return 'Answer cannot be empty';
} else {
return null;
}
},
textAlign: TextAlign.center,
decoration: InputDecoration(
enabledBorder: OutlineInputBorder(
borderSide:
BorderSide(color: Colors.blueAccent),
borderRadius: BorderRadius.all(
Radius.circular(15),
)),
labelText: 'Type your Answer',
filled: true,
fillColor: defaultcolor,
),
onFieldSubmitted: (value) {
usertitleInput.text = value;
fillColor();
correctText();
print(usertitleInput.text);
}),
),
SizedBox(
height: 10,
),
defcorrect,
SizedBox(
height: 10,
),
RaisedButton(
onPressed: () {
if (_Key.currentState.validate()) {
description(context);
// nextPictogram();
reset();
}
//
//if (_Key.currentState.validate() == correctText()) {
// nextPictogram;
// }
},
child: Text('Next'),
)
],
),
),
],
)
: Center(
child: Text('completed'),
));
}
}
my source code of the second screen is show here
class Userinputscreen extends StatefulWidget {
final String id;
final String word;
const Userinputscreen({Key key, this.id, this.word}) : super(key: key);
#override
_UserinputscreenState createState() => _UserinputscreenState();
}
class _UserinputscreenState extends State<Userinputscreen> {
final _Keey = GlobalKey<FormState>();
TextEditingController userdescription = TextEditingController();
var pictogramindex;
void nextpict(BuildContext context) {
Navigator.of(context).pushNamed('/main-screen');
}
// void nextpict(BuildContext context, int index) {
// Navigator.push(
// context,
// MaterialPageRoute(
// builder: (ctx) => Pictogramscreen(
// index: i = 0,
// )));
// }
#override
Widget build(BuildContext context) {
final routeArgs =
ModalRoute.of(context).settings.arguments as Map<String, String>;
final correctWord = routeArgs['word'];
return MaterialApp(
home: Scaffold(
body: ListView(children: <Widget>[
Padding(
padding: EdgeInsets.only(top: 50),
child: Center(
child: Container(
padding: EdgeInsets.all(20),
margin: EdgeInsets.only(top: 100),
child: Column(
crossAxisAlignment: CrossAxisAlignment.center,
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Text(
correctWord,
style: TextStyle(fontSize: 26),
),
SizedBox(
height: 10,
),
Form(
key: _Keey,
child: TextFormField(
controller: userdescription,
validator: (userdescription) {
if (userdescription.isEmpty) {
return 'Answer cannot be empty';
} else {
return null;
}
},
textAlign: TextAlign.center,
decoration: InputDecoration(
enabledBorder: OutlineInputBorder(
borderSide: BorderSide(color: Colors.blueAccent),
borderRadius: BorderRadius.all(
Radius.circular(15),
)),
labelText: 'Type your Answer',
filled: true,
),
onFieldSubmitted: (value) {
userdescription.text = value;
print(userdescription.text);
}),
),
SizedBox(
height: 10,
),
RaisedButton(
onPressed: () {
if (_Keey.currentState.validate()) {
nextpict(context);
}
},
child: Text('Next'),
)
],
),
),
),
),
])),
);
}
}

Answer 1

If I get it right, you basically want to tell the initial page that it's state is updated(the index) elsewhere. You basically need to make your app "reactive".
As is said in Google Developers Tutorial:
One of the advantages of Flutter is that it uses reactive views, which you can take to the next level by also applying reactive principles to your app’s data model.
Use some sort of state management. You need to choose from and use either Bloc, InheritedWidget and InheritedModel, Provider(ScopedModel), or the like.
Check this article on flutter about state management, or this for a complete list of approaches