FutureBuilder and async function in flutter - flutter

Question

I have a problem with FutureBuilder, it refresh and execute code again when there is a change like when i change value of radio button, i click on radio and it reloads all futurebuilder it seems.
EDIT : i have corrected the problem and here is my solution, i am not sure it works all time
My full code is :
import 'package:flutter/material.dart';
import 'dart:convert';
import 'package:http/http.dart' as http;
import 'dart:async';
// Create a Form widget.
class Affiche_grille extends StatefulWidget {
#override
_Affiche_grille_State createState() {
return _Affiche_grille_State();
}
}
// Create a corresponding State class.
// This class holds data related to the form.
class _Affiche_grille_State extends State<Affiche_grille> {
#override
final _formKey = GlobalKey<FormState>();
List<String> radioValues = [];
Future<List<Match>> grid;
Future <List<Match>> Grille_display() async {
// SERVER LOGIN API URL
var url = 'http://www.axis-medias.fr/game_app/display_grid.php';
// Store all data with Param Name.
var data = {'id_grille': 1};
// Starting Web API Call.
var response = await http.post(url, body: json.encode(data));
// Getting Server response into variable.
var jsondata = json.decode(response.body);
List<Match> Matchs = [];
for (var u in jsondata) {
Match match = Match(u["equipe1"],u["equipe2"],u["type_prono"]);
Matchs.add(match);
radioValues.add("N");
}
return Matchs;
}
void initState() {
grid = Grille_display();
super.initState();
}
#override
Widget build(BuildContext context) {
final appTitle = 'MONEYFREE';
return MaterialApp(
title: appTitle,
home: Scaffold(
appBar: AppBar(
title: Text(appTitle),
),
body: Container(
child:
FutureBuilder(
future: grid,
builder: (BuildContext context, AsyncSnapshot snapshot) {
if (snapshot.data == null) {
return Container (
child: Center(
child: Text("Chargement en cours...")
)
);
}
else {
List<Match> values = snapshot.data;
return Form(
key: _formKey,
child: Column(
crossAxisAlignment: CrossAxisAlignment.start,
children: <Widget>[
DataTable(
columnSpacing: 20,
columns: [
DataColumn(
label: Text("Libelle Match"),
numeric: false,
tooltip: "",
),
DataColumn(
label: Text("1"),
numeric: false,
tooltip: "",
),
DataColumn(
label: Text("N"),
numeric: false,
tooltip: "",
),
DataColumn(
label: Text("2"),
numeric: false,
tooltip: "",
),
],
rows:
List.generate(values.length, (index) {
return DataRow(
cells: [
DataCell(
Text(values[index].equipe1.toString() + " - " + values[index].equipe2.toString()),
),
DataCell(
Radio(
value: "1",
groupValue: radioValues[index],
onChanged: (val) {
setState(() {
radioValues[index] = val;
print('Change 1');
print(radioValues);
});
},
),
),
DataCell(
Radio(
value: "N",
groupValue: radioValues[index],
onChanged: (val) {
setState(() {
radioValues[index] = val;
print('Change N');
print(radioValues);
});
},
),
),
DataCell(
Radio(
value: "2",
groupValue: radioValues[index],
onChanged: (val) {
setState(() {
radioValues[index] = val;
print('Change 2');
print(radioValues);
});
},
),
),
]
);
}).toList(),
),
Center(
child: RaisedButton(
color: Colors.green,
textColor: Colors.white,
padding: EdgeInsets.fromLTRB(9, 9, 9, 9),
child: Text('VALIDER VOTRE GRILLE'),
onPressed: () {
Valide_grille();
},
),
),
],
)
);
};
},
),
),
),
);
}
Future Valide_grille() async{
// For CircularProgressIndicator.
bool visible = false ;
// Showing CircularProgressIndicator.
setState(() {
visible = true ;
});
// SERVER LOGIN API URL
var url = 'http://www.axis-medias.fr/game_app/valide_grid.php';
var concatenate='';
radioValues.forEach((item){
concatenate=concatenate+item;
});
// Store all data with Param Name.
var data = {'id_membre':1, 'id_grille':1,'result':concatenate};
print (data);
var grille_encode=jsonEncode(data);
print(grille_encode);
// Starting Web API Call.
var response = await http.post(url, body: grille_encode);
print(response.body);
// Getting Server response into variable.
var message = json.decode(response.body);
// If the Response Message is Matched.
if(message == 'OK')
{
print('VALIDATION DE LA GRILLE OK');
// Hiding the CircularProgressIndicator.
setState(() {
visible = false;
});
}else{
// If Email or Password did not Matched.
// Hiding the CircularProgressIndicator.
setState(() {
visible = false;
});
// Showing Alert Dialog with Response JSON Message.
showDialog(
context: context,
builder: (BuildContext context) {
return AlertDialog(
title: new Text(message),
actions: <Widget>[
FlatButton(
child: new Text("OK"),
onPressed: () {
Navigator.of(context).pop();
},
),
],
);
},
);
}
}
}
class Match {
final String equipe1;
final String equipe2;
final String typeprono;
const Match(this.equipe1, this.equipe2, this.typeprono);
}

Answer 1

You can copy paste run full code below
Reason
didUpdateWidget of the FutureBuilder state is being called every time a rebuild is issued. This function checks if the old future object is different from the new one, and if so, refires the FutureBuilder.
https://github.com/flutter/flutter/issues/11426#issuecomment-414047398
Solution
Future _future;
#override
void initState() {
// TODO: implement initState
_future = Grille_display();
}
...
child: FutureBuilder(
future: _future,
working demo
full code
import 'package:flutter/material.dart';
import 'dart:convert';
import 'package:http/http.dart' as http;
import 'dart:async';
// Create a Form widget.
class Affiche_grille extends StatefulWidget {
#override
_Affiche_grille_State createState() {
return _Affiche_grille_State();
}
}
// Create a corresponding State class.
// This class holds data related to the form.
class _Affiche_grille_State extends State<Affiche_grille> {
#override
final _formKey = GlobalKey<FormState>();
List<String> radioValues = [];
Future<List<Match>> Grille_display() async {
// SERVER LOGIN API URL
var url = 'http://www.axis-medias.fr/game_app/display_grid.php';
// Store all data with Param Name.
var data = {'id_grille': 1};
// Starting Web API Call.
var response = await http.post(url, body: json.encode(data));
// Getting Server response into variable.
var jsondata = json.decode(response.body);
List<Match> Matchs = [];
for (var u in jsondata) {
Match match = Match(u["equipe1"], u["equipe2"], u["type_prono"]);
Matchs.add(match);
}
return Matchs;
}
Future _future;
#override
void initState() {
// TODO: implement initState
_future = Grille_display();
}
#override
Widget build(BuildContext context) {
final appTitle = 'MONEYFREE';
return MaterialApp(
title: appTitle,
home: Scaffold(
appBar: AppBar(
title: Text(appTitle),
),
body: Container(
child: FutureBuilder(
future: _future,
builder: (BuildContext context, AsyncSnapshot snapshot) {
if (snapshot.data == null) {
return Container(
child: Center(child: Text("Chargement en cours...")));
} else {
List<Match> values = snapshot.data;
values.forEach((m) {
radioValues.add("N");
//like N or something
});
print('valeur radio après initialisation');
print(radioValues);
return Form(
key: _formKey,
child: Column(
crossAxisAlignment: CrossAxisAlignment.start,
children: <Widget>[
DataTable(
columnSpacing: 20,
columns: [
DataColumn(
label: Text("Libelle Match"),
numeric: false,
tooltip: "",
),
DataColumn(
label: Text("1"),
numeric: false,
tooltip: "",
),
DataColumn(
label: Text("N"),
numeric: false,
tooltip: "",
),
DataColumn(
label: Text("2"),
numeric: false,
tooltip: "",
),
],
rows: List.generate(values.length, (index) {
return DataRow(cells: [
DataCell(
Text(values[index].equipe1.toString() +
" - " +
values[index].equipe2.toString()),
),
DataCell(
Radio(
value: "1",
groupValue: radioValues[index],
onChanged: (val) {
setState(() {
radioValues[index] = val;
print('Change 1');
print(radioValues);
});
},
),
),
DataCell(
Radio(
value: "N",
groupValue: radioValues[index],
onChanged: (val) {
setState(() {
radioValues[index] = val;
print(radioValues);
});
},
),
),
DataCell(
Radio(
value: "2",
groupValue: radioValues[index],
onChanged: (val) {
setState(() {
radioValues[index] = val;
print(radioValues);
});
},
),
),
]);
}).toList(),
),
Center(
child: RaisedButton(
color: Colors.green,
textColor: Colors.white,
padding: EdgeInsets.fromLTRB(9, 9, 9, 9),
child: Text('VALIDER VOTRE GRILLE'),
onPressed: () {
Valide_grille();
},
),
),
],
));
}
;
},
),
),
),
);
}
Future Valide_grille() async {
// For CircularProgressIndicator.
bool visible = false;
// Showing CircularProgressIndicator.
setState(() {
visible = true;
});
// SERVER LOGIN API URL
var url = 'http://www.axis-medias.fr/game_app/valide_grid.php';
// Store all data with Param Name.
var data = jsonEncode(radioValues);
print(radioValues);
// Starting Web API Call.
var response = await http.post(url, body: json.encode(data));
// Getting Server response into variable.
var message = json.decode(response.body);
// If the Response Message is Matched.
if (message == 'OK') {
print('VALIDATION DE LA GRILLE OK');
// Hiding the CircularProgressIndicator.
setState(() {
visible = false;
});
} else {
// If Email or Password did not Matched.
// Hiding the CircularProgressIndicator.
setState(() {
visible = false;
});
// Showing Alert Dialog with Response JSON Message.
showDialog(
context: context,
builder: (BuildContext context) {
return AlertDialog(
title: new Text(message),
actions: <Widget>[
FlatButton(
child: new Text("OK"),
onPressed: () {
Navigator.of(context).pop();
},
),
],
);
},
);
}
}
}
class Match {
final String equipe1;
final String equipe2;
final String typeprono;
const Match(this.equipe1, this.equipe2, this.typeprono);
}
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
primarySwatch: Colors.blue,
),
home: Affiche_grille(),
);
}
}
class MyHomePage extends StatefulWidget {
MyHomePage({Key key, this.title}) : super(key: key);
final String title;
#override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
int _counter = 0;
void _incrementCounter() {
setState(() {
_counter++;
});
}
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text(widget.title),
),
body: Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Text(
'You have pushed the button this many times:',
),
Text(
'$_counter',
style: Theme.of(context).textTheme.headline4,
),
],
),
),
floatingActionButton: FloatingActionButton(
onPressed: _incrementCounter,
tooltip: 'Increment',
child: Icon(Icons.add),
),
);
}
}