A Good day to everyone. So I'm fairly new to flutter and I have a page where I take in two inputs in a search fieldstone them in different variables(_selectedYear and _selectedSem) and based on the inputs I create a url. On creating the two search fields and running it , if I input in the second field before the first one, I have no error but if I input in the first field before the second field this error pops up.
This widget has been unmounted, so the State no longer has a context (and should be considered defunct). Consider canceling any active work during dispose or using the getter mounted to determine if the state is still active.
Here's a screenshot of the page.Click here
Here is the code.
class _TestrState extends State<Testr> {
String _selectedYear;
String _selectedSem;
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
elevation: 0,
backgroundColor: Colors.white,
title: const Text(
'Testr',
style: TextStyle(
color: Colors.black,
),
),
flexibleSpace: Container(
decoration: const BoxDecoration(
gradient: LinearGradient(
begin: Alignment.centerLeft,
end: Alignment.bottomRight,
colors: [Colors.green, Colors.limeAccent])),
),
),
body: Container(
child: SingleChildScrollView(
child: Column(
crossAxisAlignment: CrossAxisAlignment.start,
mainAxisAlignment: MainAxisAlignment.spaceBetween,
children: [
Container(
height: MediaQuery.of(context).size.height * 0.64,
child: Column(
crossAxisAlignment: CrossAxisAlignment.start,
mainAxisAlignment: MainAxisAlignment.center,
children: [
const Padding(
padding: EdgeInsets.all(20.0),
child: Text(
'Select a Year',
style: TextStyle(fontSize: 16, color: Colors.blueGrey),
),
),
Container(
width: double.infinity,
margin: const EdgeInsets.symmetric(horizontal: 20),
decoration: BoxDecoration(
color: Colors.white,
borderRadius: BorderRadius.circular(10),
boxShadow: [
BoxShadow(
color: Colors.grey.withOpacity(0.2),
blurRadius: 10,
offset: const Offset(0, 10),
),
],
),
child: SearchField(
hint: 'Search for Year',
searchInputDecoration: InputDecoration(
enabledBorder: OutlineInputBorder(
borderSide: BorderSide(
color: Colors.blueGrey.shade200,
width: 1,
),
borderRadius: BorderRadius.circular(10),
),
focusedBorder: OutlineInputBorder(
borderSide: BorderSide(
width: 2,
color: Colors.blue.withOpacity(0.8),
),
borderRadius: BorderRadius.circular(10),
),
),
maxSuggestionsInViewPort: 4,
itemHeight: 50,
suggestionsDecoration: BoxDecoration(
color: Colors.white,
borderRadius: BorderRadius.circular(10),
),
onTap: (value) {
setState(() {
_selectedYear = value;
});
if (kDebugMode) {
print(value);
}
},
suggestions: const [
'Year One',
'Year Two',
'Year Three',
'Year Four',
],
),
),
const Padding(
padding: EdgeInsets.all(20.0),
child: Text(
'Select a Semester',
style: TextStyle(fontSize: 16, color: Colors.blueGrey),
),
),
Container(
width: double.infinity,
margin: const EdgeInsets.symmetric(horizontal: 20),
decoration: BoxDecoration(
color: Colors.white,
borderRadius: BorderRadius.circular(10),
boxShadow: [
BoxShadow(
color: Colors.grey.withOpacity(0.2),
blurRadius: 10,
offset: const Offset(0, 10),
),
],
),
child: SearchField(
hint: 'Search for Semester',
searchInputDecoration: InputDecoration(
enabledBorder: OutlineInputBorder(
borderSide: BorderSide(
color: Colors.blueGrey.shade200,
width: 1,
),
borderRadius: BorderRadius.circular(10),
),
focusedBorder: OutlineInputBorder(
borderSide: BorderSide(
width: 2,
color: Colors.blue.withOpacity(0.8),
),
borderRadius: BorderRadius.circular(10),
),
),
maxSuggestionsInViewPort: 4,
itemHeight: 50,
suggestionsDecoration: BoxDecoration(
color: Colors.white,
borderRadius: BorderRadius.circular(10),
),
onTap: (value) {
setState(() {
_selectedSem = value;
});
if (kDebugMode) {
print(value);
}
},
suggestions: const [
'Afghanistan',
'Turkey',
'Germany',
'France',
'Italy',
],
),
),
],
),
),
Container(
height: 90,
padding: const EdgeInsets.only(right: 20, left: 20, bottom: 20),
decoration: const BoxDecoration(
color: Colors.white,
),
child: Row(
mainAxisAlignment: MainAxisAlignment.spaceBetween,
children: [
_selectedYear == null
? const Text(
'Select a Year and a Semester to Continue',
style:
TextStyle(fontSize: 14, color: Colors.blueGrey),
)
: Text(_selectedYear "->" _selectedSem,
style: TextStyle(
fontSize: 16,
color: Colors.grey.shade800,
fontWeight: FontWeight.w600)),
MaterialButton(
onPressed: () {
CreateURL(_selectedYear, _selectedSem);
},
color: Colors.black,
minWidth: 50,
height: 50,
shape: RoundedRectangleBorder(
borderRadius: BorderRadius.circular(50),
),
padding: const EdgeInsets.all(0),
child: const Icon(
Icons.arrow_forward_ios,
color: Colors.blueGrey,
size: 24,
),
)
],
),
)
],
),
),
),
);
}
}
Ive tried placing the setstate in an 'if(mounted)' and that didn't work after looking at other similar questions.
Anyone mind helping me out?
CodePudding user response：
i just changed the variables initialization and it worked.
String _selectedYear = "";
String _selectedSem = "";
and also added this logic to the setState
setState(() {
_selectedSem = value!;
});
this did the trick for me, try it out and see
CodePudding user response：
I'm not sure but once you try this way. first, initialize value to a variable and then refresh state
_selectedYear = value;
setState(() {});
or if you are using flutter version 2.5.3 or higher then you need to initialize variable or migrate to null safety.