Flutter setState() make a loop to be always recalled - dart

Question

I have a code like this below, the simple flow is I make a loop from a list of objects to create some widgets.
class ScoringAttribute {
int _id;
bool _isdelete;
double _scorehigh, _scorelow, _scorevalue;
String _name, _scoretype, _description, _title;
}
class HomePageState extends State<HomePage> with TickerProviderStateMixin {
List dataScoringAttributes;
List<ScoringAttribute> listScoringAttributeObjects = new List<ScoringAttribute>();
final String urlPresentation = ".../.resentations/getPresentations";
final String urlScoringAttribute = ".../.scoringattributes/getScoringattributes";
Future<String> getPresentationData() async {
var responseScoringAttribute = await http.get(
Uri.encodeFull(urlScoringAttribute),
headers: {"Accept": "application/json"}
);
var scoringAttributeJson = json.decode(responseScoringAttribute.body);
dataScoringAttributes = scoringAttributeJson['scoringattributes'];
for(int i = 0; i < dataScoringAttributes.length; i++) {
var scoringAttributeObject = new ScoringAttribute();
scoringAttributeObject._id = dataScoringAttributes[i]["id"];
scoringAttributeObject._description = dataScoringAttributes[i]["iddescription"];
scoringAttributeObject._isdelete = dataScoringAttributes[i]["isdelete"];
scoringAttributeObject._name = dataScoringAttributes[i]["name"];
scoringAttributeObject._scorehigh = double.parse(dataScoringAttributes[i]["scorehigh"].toString());
scoringAttributeObject._scorelow = double.parse(dataScoringAttributes[i]["scorelow"].toString());
scoringAttributeObject._scoretype = dataScoringAttributes[i]["scoretype"];
scoringAttributeObject._title = dataScoringAttributes[i]["title"];
scoringAttributeObject._scorevalue = double.parse(dataScoringAttributes[i]["scorelow"].toString());
listScoringAttributeObjects.add(scoringAttributeObject);
}
return "Success";
}
List<Widget> scoringAttributeList() {
List<Widget> list = new List();
for(int i = 0; i < listScoringAttributeObjects.length; i++) {
if(listScoringAttributeObjects[i]._scoretype == "slider") {
list.add(
new Container(
child: new Column(
children: <Widget>[
new Column(
children: <Widget>[
//THE SLIDER VALUE TEXT
new Text(
//CONVERT DOUBLE TYPE TO STRING WITHOUT DECIMAL POINTS
listScoringAttributeObjects[i]._scorevalue.toStringAsFixed(listScoringAttributeObjects[i]._scorevalue.truncateToDouble() == listScoringAttributeObjects[i]._scorevalue ? 0 : 0),
style: new TextStyle(
fontSize: 28.0,
),
),
//THE SLIDER
new Slider(
activeColor: Colors.blueAccent,
inactiveColor: const Color(0xFFb7d2e0),
min: double.parse(listScoringAttributeObjects[i]._scorelow.toString()),
max: double.parse(listScoringAttributeObjects[i]._scorehigh.toString()),
value: double.parse(listScoringAttributeObjects[i]._scorevalue.toString()),
onChanged: (double value) {
setState(() {
listScoringAttributeObjects[i]._scorevalue = double.parse(value.round().toString());
});
},
),
],
),
],
),
),
);
}
else if(listScoringAttributeObjects[i]._scoretype == "text_field") {
list.add(...);
}
else if(listScoringAttributeObjects[i]._scoretype == "stars") {
list.add(...);
}
else if(listScoringAttributeObjects[i]._scoretype == "thumb") {
list.add(new Container(...);
}
}
return list;
}
#override
Widget build(BuildContext context) {
return new Scaffold(
body: FutureBuilder<String> (
future: getPresentationData(),
builder: (context, snapshot) {
if(snapshot.hasData) {
return new Column(
children: <Widget>[
new Column(
children: scoringAttributeList(),
),
],
),
}
},
),
);
}
}
There are some different widgets depending on the type, and there are 4 types, and 1 type might have more than 1 widget in it, so I make the loop depend on the data that it got from DB.
The problem is I don't know why every time I use setState() inside the loop, it always processes the loop again, so it'll be an infinite loop to create a new widget, and it'll duplicate the widget from the beginning (only happen when the setState() is called).
Ex: there are 4 data inside the List, and if the setState() is called, it'll show 8 data (show the first 4 data twice)
Here's the example of how I setState() into the data inside the List
onChanged: (double value) {
setState(() {
listScoringAttributeObjects[i]._scorevalue = double.parse(value.round().toString());
});
},
I think the problem is because I setState() into some data inside the List. So when the List state is changed, it'll re-render anything that is related to the List.
Is it true?
If yes, is there any other solution how to change my code?
If not, is there any mistake in my code or my logic maybe?
Thank you. Really looking forward to some solution about this, cause I really got stuck in this, and its already been a week :(

Answer 1

Simple move your getPresentationData() into state variable. So that it will get triggered only once.
class HomePageState extends State<HomePage> with TickerProviderStateMixin {
Future<String> _presentationFuture;
initState() {
_presentationFuture = getPresentationData()
}
//other contents
#override
Widget build(BuildContext context) {
return new Scaffold(
body: FutureBuilder<String> (
future: _presentationFuture,
builder: (context, snapshot) {
if(snapshot.hasData) {
Reason for duplicate: we can calling setState on Slider dataChange which will re-render the HomePageState which will again trigger the network call (getPresentationData())
Note: If you want to trigger network on slider change, clear the list before making a network call
Future<String> getPresentationData() async {
listScoringAttributeObjects = new List<ScoringAttribute>(); // clear data
var responseScoringAttribute = await http.get(
Uri.encodeFull(urlScoringAttribute),
headers: {"Accept": "application/json"}
);

Answer 2

I don't see how this would be related to the one setState() in your code. It is only called when the slider is used.
I think the problem is caused by list.add(...); in scoringAttributeList(). You shouldn't modify data when build() is executed.
You should assume that build() can be called repeatedly and at any time.
Build your code so that this doesn't cause issues when it happens.