How to access array inside array in flutter

Question

Here i got some list of array

 {
    "id": 1,
    "username": "dragonknight",
    "password": "123",
    "email": "[email protected]",
    "nama_lengkap": "Dragon Knight",
    "createdAt": "2022-04-13T05:50:00.559Z",
    "updatedAt": "2022-04-13T05:50:00.559Z",
    "grupId": 1,
    "grup": {
        "id": 1,
        "nama_grup": "fleetime",
        "deskripsi": "Ini deskripsi",
        "createdAt": "2022-04-13T05:53:18.423Z",
        "updatedAt": "2022-04-13T05:53:18.423Z"
    }
},

the problem is i want to enter grup array and enter nama_grup in flutter how do i do that. i tried with username and nama_lengkap and data show up correctly. but with grup it shows as null.

home.dart

https://pastebin.com/raw/F3Ha8vKK

could you clarify your question it's quite hard to under stand? provide what's happening and what you want — Ruchit
– Ruchit, Commented Apr 14, 2022 at 3:47
I want to show group name dynamically from an API. and i want to show it in Flutter frontend. tthe problem is when i access an array within an array i got null. — fleetime
– fleetime, Commented Apr 14, 2022 at 3:50
My home.dart dashboard when i access normal array nama_lengkap and it does works. but when i tried nama_grup it shows as null pastebin.com/raw/F3Ha8vKK — fleetime
– fleetime, Commented Apr 14, 2022 at 3:53

test · Accepted Answer · 2022-04-14 08:17:22Z

1

You need to separate grup from object then access it. Wait for shared instance loaded then find for user string, if found do the json decode. Here is the working example:

class _DashboardState extends State<Dashboard> {
  final Future<SharedPreferences> localStorage = SharedPreferences.getInstance();
  String nama_grup = '';

  @override
  void initState() async {
    super.initState();

    // wait for SharedPreferences instance
    final prefs = await localStorage;

    // find user string from SharedPreferences
    final String? user = prefs.getString('user');

    var userGrup = [];

    if (user != null) {
      // decode json string if found
      var userDecoded = json.decode(user);

      setState(() {
        userGrup.add(userDecoded['grup']);
        nama_grup = userGrup[0]['nama_grup'];
      });
    }
  }
  ...

edited Apr 14, 2022 at 8:17

answered Apr 14, 2022 at 5:50

test

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3 Comments

fleetime Over a year ago

It says the method [] was called on null imgur.com/96vAWtd

fleetime Over a year ago

full code : github.com/fleetimee/frontend_akm/blob/master/lib/screens/…

test Over a year ago

You might need do json decode after finding user String see updated code.

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