Make a variable in build build context run once - flutter

Question

I have a stateful widget which uses a provider to get questions. The question type looks like this:
{
"question": "What...",
"answer: 1829,
"buffer": [1928, 1874, 1825]
}
I have a shuffle method which shuffles the items passed to it. So in my widget, I have this code:
#override
Widget build(BuildContext context) {
var state = context.watch<Services>();
Tion tion;
List<int> shuffled;
int selectedNumber;
if (state.questions != null) {
tion = state.questions[0];
shuffled = shuffle([tion.answer, ...tion.buffer]); // here's my issue
}
return ...
}
Deeper in the widget tree, I render these numbers:
GridView.count(
crossAxisCount: 2,
children: List.generate(4, (index) =>
Center(
child: GestureDetector(
onTap: () => setState(() {
selectedNumber = shuffled[index]; // setstate
}),
child: Container(
width: 100,
height: 100,
decoration: BoxDecoration(
color: selectedNumber == shuffled[index] ? Color(0xff6C63FF) : Colors.grey[200],
borderRadius: BorderRadius.all(
Radius.circular(10)
)
),
child: Center(
child: Text(
'${shuffled[index]}',
style: GoogleFonts.lato(
fontSize: 16,
fontWeight: FontWeight.bold,
color: Colors.grey[800]
)
)
),
),
),
)
),
)
The problem is when I call setState(), the widget rebuilds, and the order of the numbers along with it. Is there any way to prevent this? I tries with initState but it's called outside the scope of context.

Answer 1

If you need a BuildContext for your function you can use didChangeDependencies(): It is called when a dependency of this State object changes and also immediately after initState, it is safe to use BuildContext here. Subclasses rarely override this method because the framework always calls build after a dependency changes. Some subclasses do override this method because they need to do some expensive work (e.g., network fetches) when their dependencies change, and that work would be too expensive to do for every build.
#override
void didChangeDependencies() {
// Your function.
super.didChangeDependencies();
}
Getx package also has variety of ways to insert a Middleware function. You can check them on package page.