Get data from JSON and add into the List on initState() - dart

Question

I have JSON file below.
Data.json
[{
"rownum": 1,
"total": 10.99793271,
"total2": 106.65666751,
}, {
"rownum": 2,
"total": 10.99793271,
"total2": 106.65666751,
}]
and the class Item and List
List <Item> item;
class Item {
String row;
String total;
String total2;
Student({this.row, this.total, this.total2});
}
How can I get data from data.json and add them into List <Item> item on the initState()?
Like this
class MyAppState extends State<MyApp> {
#override
void initState() {
Future<String> _loadAStudentAsset() async {
return await rootBundle.loadString('assets/data.json');
}
//....some code to add value into list
super.initState();
}

Answer 1

That solution is also valid for you:
Flutter: How to display a short text file from assets on screen of phone?
If we make another example with same template:
import 'dart:convert';
import 'package:flutter/material.dart';
import 'package:flutter/services.dart' show rootBundle;
void main() {
runApp(Test());
}
class Test extends StatefulWidget {
#override
_TestState createState() => _TestState();
}
class _TestState extends State<Test> {
Future _future;
Future<String> loadString() async =>
await rootBundle.loadString('assets/data.json');
#override
void initState() {
_future = loadString();
super.initState();
}
#override
Widget build(BuildContext context) {
return MaterialApp(
home: Scaffold(
body: FutureBuilder(
future: _future,
builder: (context, AsyncSnapshot snapshot) {
if (!snapshot.hasData) {
return Text('Loading...');
}
List<dynamic> parsedJson = jsonDecode(snapshot.data);
items = parsedJson.map((element) {
return Item(
row: element['rownum'].toString(),
total: element['total'].toString(),
total2: element['total2'].toString(),
);
}).toList();
;
return ListView.builder(
itemCount: items.length,
itemBuilder: (context, index) {
final item = items[index];
return Column(
children: <Widget>[
Text(item.row),
Text(item.total),
Text(item.total2),
],
);
},
);
},
),
),
);
}
}
List<Item> items;
class Item {
String row;
String total;
String total2;
Item({this.row, this.total, this.total2});
}

Answer 2

class Item {
static final String db_row = "rownum";
static final String db_total = "total";
static final String db_total2 = "total2";
int row;
double total;
double total2;
Item({this.row, this.total, this.total2});
Item.fromMap(Map map) {
this.row = map[Item.db_row];
this.total = map[Item.db_total];
this.total2 = map[Item.db_total2];
}
Map toMap() =>
{Item.db_row: row, Item.db_total: total, Item.db_total2: total2};
static List<Item> fromMapList(mapList) {
List<Item> items = new List();
new List.from(mapList).forEach((mapItem) {
items.add(Item.fromMap(mapItem));
});
return items;
}
}
And
List <Item> items = Item.fromMapList(await rootBundle.loadString('assets/data.json'));