Flutter: Access data from JSON file & convert it to Object - dart

Question

I've following Json stored inside Assets/JSON/example.json
[
{"optiontext" : "One", "optionvalue" : "One"},
{"optiontext" : "Two", "optionvalue" : "Two"},
{"optiontext" : "Three", "optionvalue" : "Three"}
]
I want to read JSON from this file & convert it to MyObject.
Have to use it in Flutter App

Answer 1

Here is sample code snippet for your case. Basically, we can use dartson package for converting.
import 'package:dartson/dartson.dart';
void main(List<String> args) {
String jsonString = '[{"optiontext" : "One", "optionvalue" : "One"},{"optiontext" : "Two", "optionvalue" : "Two"},{"optiontext" : "Three", "optionvalue" : "Three"}]';
var dson = new Dartson.JSON();
List<MyObject> result = dson.decode(jsonString, new MyObject(), true);
print(result[1].optionValue);
}
#Entity()
class MyObject {
#Property(name:"optiontext")
String optionText;
#Property(name:"optionvalue")
String optionValue;
}
As you can't use dartson in flutter due to some issue, the below code snippet can be used with the help of dart:convert
import 'dart:convert';
void main(List<String> args) {
String jsonString = '[{"optiontext" : "One", "optionvalue" : "Value"},{"optiontext" : "Two", "optionvalue" : "Two"},{"optiontext" : "Three", "optionvalue" : "Three"}]';
List<Map> parsedJson = JSON.decode(jsonString);
List<MyObject> result = parsedJson.map((item) => new MyObject.fromJson(item)).toList();
print(result[0].optionText);
print(result[0].optionValue);
}
class MyObject {
String optionText;
String optionValue;
MyObject.fromJson(Map jsonMap)
: optionText = jsonMap['optiontext'],
optionValue = jsonMap['optionvalue'];
}

Answer 2

Here is my solution
I have the following json
[
{
"name": "Abhijit Sawant",
"age": "23",
"height":"180",
"gender": "male",
"hair_color": "black"
},
{
"name": "Akku Sawant",
"age": "23",
"height":"150",
"gender": "male",
"hair_color": "brown"
},
{
"name": "Pikki Sawant",
"age": "23",
"height":"120",
"gender": "male",
"hair_color": "grey"
},
{
"name": "Chikki Sawant",
"age": "23",
"height":"100",
"gender": "female",
"hair_color": "white"
}
]
Following is my Flutter Code
class HomePage extends StatefulWidget {
#override
State<StatefulWidget> createState() {
return HomePageState();
}
}
class HomePageState extends State<HomePage>{
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(title: Text("Loading Json"),),
body: Container(
child: Center(
child: FutureBuilder(builder: (context,snapshot){
var myData = json.decode(snapshot.data.toString());
return new ListView.builder(
itemCount: myData == null ? 0: myData.length,
itemBuilder: (BuildContext context,int index){
return Card(
child: Column(
crossAxisAlignment: CrossAxisAlignment.stretch,
children: <Widget>[
Text("Name: "+myData[index]["name"]),
Text("Age: "+myData[index]["age"]),
Text("Height: "+myData[index]["height"]),
Text("Gender: "+myData[index]["gender"]),
],
),
);
},);
},
future: DefaultAssetBundle.of(context).loadString("person.json"),),
),
),
);
}
}