How to parse json dynamic array name

Question

Need to parse this json which has a dynamic array key . tried with for each key,value statement but still its not working .

{ 
"68": [
         {
            "id": 173,
            "user_id": 21
        },
        {
            "id": 174,
            "user_id": 21
        }
    ],
    "70": [
        {
            "id": 175,
            "user_id": 21
        },
        {
            "id": 176,
            "user_id": 21
        }
    ]
}

so far i tried to parse like this but its not working it gives me an error ''Unhandled Exception: type 'List<dynamic>' is not a subtype of type 'Map<String, dynamic>' ''

class MyOrdersModel {

  final List<MyOrders> myorders;

  MyOrdersModel({
    this.myorders,
  });

factory MyOrdersModel.fromJson(Map<String, dynamic> parsedJson) {

    var list = new List();
    parsedJson.forEach((key, value){
      list.add(value);
      //print("array_key" + key);

    });

    print(list); 

    List<MyOrders> myorders = new List<MyOrders>();
    myorders = list.map((i) => MyOrders.fromJson(i)).toList();

    return new MyOrdersModel(myorders: myorders);
  }
}

Answer 1

Your json data:

1: { 
2:   "68": [
3:     {"id": 173,"user_id": 21},
4:     {"id": 174,"user_id": 21}],
5:   "70": [
6:     {"id": 175, "user_id": 21},
7:     {"id": 176, "user_id": 21}]}

Your code:

factory MyOrdersModel.fromJson(Map<String, dynamic> parsedJson) {
    var list = new List();
    // parsedJson = {"68": [{"id": 173,"user_id": 21}, {"id": 174,"user_id": 21}], "70": [{"id": 175, "user_id": 21}, {"id": 176, "user_id": 21}]}
    parsedJson.forEach((key, value){
      // First time: value = [{"id": 173,"user_id": 21}, {"id": 174,"user_id": 21}]
      // Second time: value = [{"id": 175, "user_id": 21}, {"id": 176, "user_id": 21}]
      list.add(value);
      //print("array_key" + key);
    });
    print(list); 
    List<MyOrders> myorders = new List<MyOrders>();
    // First time: i = [{"id": 173,"user_id": 21}, {"id": 174,"user_id": 21}]
    // ★ => That's list => `Unhandled Exception: type 'List<dynamic>' is not a subtype of type 'Map<String, dynamic>'`
    myorders = list.map((i) => MyOrders.fromJson(i)).toList();
    return new MyOrdersModel(myorders: myorders);
  }
}

Solution:

class MyOrdersModel {

  final List<MyOrders> myorders;

  MyOrdersModel({this.myorders});}

  factory MyOrdersModel.fromJson(Map<String, dynamic> parsedJson) {
    var list = new List();
    parsedJson.forEach((key, value){
      value.forEach((value) {
        list.add(value);
      });
    });

    print(list); 

    List<MyOrders> myorders = new List<MyOrders>();
    myorders = list.map((i) => MyOrders.fromJson(i)).toList();

    return new MyOrdersModel(myorders: myorders);
  }
}

Answer 2

You can copy paste run full code below
assume 68, 70 means order no
parse with json.decode and convert to Order List

code snippet

class Order {
  String no;
  dynamic data;

  Order(this.no ,this.data);
}

dynamic Obj = json.decode(jsonString);
List<Order> orderList = [];
Obj.forEach((k, v) => orderList.add(Order(k,v)));

print('${orderList[0].no}');
print('${orderList[0].data[0]["id"]}');
print('${orderList[0].data[1]["id"]}');

full code

import 'package:flutter/material.dart';
import 'dart:async';
import 'dart:convert';

void main() => runApp(MyApp());

class Order {
  String no;
  dynamic data;

  Order(this.no ,this.data);
}

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        // This is the theme of your application.
        //
        // Try running your application with "flutter run". You'll see the
        // application has a blue toolbar. Then, without quitting the app, try
        // changing the primarySwatch below to Colors.green and then invoke
        // "hot reload" (press "r" in the console where you ran "flutter run",
        // or simply save your changes to "hot reload" in a Flutter IDE).
        // Notice that the counter didn't reset back to zero; the application
        // is not restarted.
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);

  // This widget is the home page of your application. It is stateful, meaning
  // that it has a State object (defined below) that contains fields that affect
  // how it looks.

  // This class is the configuration for the state. It holds the values (in this
  // case the title) provided by the parent (in this case the App widget) and
  // used by the build method of the State. Fields in a Widget subclass are
  // always marked "final".

  final String title;

  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  int _counter = 0;
  String jsonString = '''{ 
"68": [
         {
            "id": 173,
            "user_id": 21
        },
        {
            "id": 174,
            "user_id": 21
        }
    ],
    "70": [
        {
            "id": 175,
            "user_id": 21
        },
        {
            "id": 176,
            "user_id": 21
        }
    ]
}
''';

  void _incrementCounter() {

    dynamic Obj = json.decode(jsonString);
    List<Order> orderList = [];
    Obj.forEach((k, v) => orderList.add(Order(k,v)));

    print('${orderList[0].no}');
    print('${orderList[0].data[0]["id"]}');
    print('${orderList[0].data[1]["id"]}');

    setState(() {
      // This call to setState tells the Flutter framework that something has
      // changed in this State, which causes it to rerun the build method below
      // so that the display can reflect the updated values. If we changed
      // _counter without calling setState(), then the build method would not be
      // called again, and so nothing would appear to happen.
      _counter++;
    });
  }

  @override
  Widget build(BuildContext context) {
    // This method is rerun every time setState is called, for instance as done
    // by the _incrementCounter method above.
    //
    // The Flutter framework has been optimized to make rerunning build methods
    // fast, so that you can just rebuild anything that needs updating rather
    // than having to individually change instances of widgets.
    return Scaffold(
      appBar: AppBar(
        // Here we take the value from the MyHomePage object that was created by
        // the App.build method, and use it to set our appbar title.
        title: Text(widget.title),
      ),
      body: Center(
        // Center is a layout widget. It takes a single child and positions it
        // in the middle of the parent.
        child: Column(
          // Column is also a layout widget. It takes a list of children and
          // arranges them vertically. By default, it sizes itself to fit its
          // children horizontally, and tries to be as tall as its parent.
          //
          // Invoke "debug painting" (press "p" in the console, choose the
          // "Toggle Debug Paint" action from the Flutter Inspector in Android
          // Studio, or the "Toggle Debug Paint" command in Visual Studio Code)
          // to see the wireframe for each widget.
          //
          // Column has various properties to control how it sizes itself and
          // how it positions its children. Here we use mainAxisAlignment to
          // center the children vertically; the main axis here is the vertical
          // axis because Columns are vertical (the cross axis would be
          // horizontal).
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            Text(
              'You have pushed the button this many times:',
            ),
            Text(
              '$_counter',
              style: Theme.of(context).textTheme.display1,
            ),
          ],
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: _incrementCounter,
        tooltip: 'Increment',
        child: Icon(Icons.add),
      ), // This trailing comma makes auto-formatting nicer for build methods.
    );
  }
}

output

I/flutter (10209): 68
I/flutter (10209): 173
I/flutter (10209): 174