list data API not showing in flutter

Question

I want to display a list based on the ID selected by the user on the detail page but when I try to implement it the data doesn't appear on the detail page and only displays a circularprogressIndicator. is there something wrong with what i'm doing here? I'm a bit confused here, and want to display List in the widget Thank You.

class DetailPage extends StatefulWidget {

  final Datum posts;
  const DetailPage({Key? key, required this.posts}) : super(key: key);

  @override
  State<DetailPage> createState() => _DetailPageState();
}

class _DetailPageState extends State<DetailPage> {
  Future<List<Mk>> getDetail(String id) async {
    String url = Constant.baseURL;
    String token = await UtilSharedPreferences.getToken();
    final response = await http.get(
      Uri.parse(
        '$url/auth/mhs_siakad/kurikulum/detail/$id',
      ),
      headers: {
        'Authorization': 'Bearer $token',
      },
    );
    print(response.statusCode);
    print(response.body);
    if (response.statusCode == 201) {
      final result = json.decode(response.body) as Map<String, dynamic>;
      Data detailKurikulum = Data.fromJson(result['data']);
      List<Mk>? l = detailKurikulum.mk;
      return l!;
    } else {
      throw Exception();
    }
  }

  Future<List<Mk>>? futureMk;

  // void initState(String id) {
  //   futureMk = DetailKurikulumProvider.getDetail(id);
  // }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: const PreferredSize(
        preferredSize: Size.fromHeight(kToolbarHeight),
        child: CustomAppbar(
          title: 'Detail Kurikulum',
        ),
      ),
      body: SafeArea(
        child: Padding(
          padding: const EdgeInsets.all(16),
          child: Column(
            crossAxisAlignment: CrossAxisAlignment.start,
            children: [
              headerDetail(),
              bodyDetail(),
              Text(
                'id: ${widget.posts.name}',
              ),
              Text('Title: ${widget.posts.prodi}'),
              const SizedBox(
                height: 20,
              ),
              const Text('Body: '),
              Text(widget.posts.id.toString()),
            ],
          ),
        ),
      ),
    );
  }

......

  Widget bodyDetail() {
    return FutureBuilder<List<Mk>>(
      future: futureMk,
      builder: (context, snapshot) {
        if (snapshot.hasData) {
          return Expanded(
            child: ListView.builder(
              physics: const BouncingScrollPhysics(),
              itemCount: snapshot.data!.length,
              itemBuilder: (context, index) {
                return Padding(
                  padding: const EdgeInsets.symmetric(vertical: 3),
                  child: Container(
                    decoration: BoxDecoration(
                      color: Colors.white,
                      borderRadius: const BorderRadius.all(
                        Radius.circular(8),
                      ),
                      boxShadow: [
                        BoxShadow(
                          color: Colors.grey.withOpacity(0.2),
                          spreadRadius: 1,
                          blurRadius: 9,
                          offset: const Offset(
                            1,
                            2,
                          ),
                        ),
                      ],
                    ),
                    child: Padding(
                      padding: const EdgeInsets.all(8),
                      child: ExpansionTile(
                        textColor: Colors.black,
                        iconColor: primaryColor,
                        collapsedIconColor: primaryColor,
                        title: Text(snapshot.data![index].matakuliah.toString(),
                            style: boldTile),
                        children: <Widget>[
                          Text(
                            'Bobot Mata Kuliah (SKS)',
                            style: bold6,
                          ),
                          Table(
                            border: TableBorder.all(color: Colors.grey),
                            children: [
                              TableRow(children: [
                                Column(children: [Text('Wajib', style: bold6)]),
                                Column(
                                    children: [Text('Pilihan', style: bold6)]),
                                Column(children: [
                                  Text('Sertifikat', style: bold6)
                                ]),
                              ]),
                              TableRow(children: [
                                Column(children: [
                                  Text(
                                      snapshot.data![index].jumlahSksWajib
                                          .toString(),
                                      style: regular6,
                                      textAlign: TextAlign.center)
                                ]),
                                Column(children: [
                                  Text(
                                      snapshot.data![index].jumlahSksPilihan
                                          .toString(),
                                      style: regular6,
                                      textAlign: TextAlign.center)
                                ]),
                                Column(children: [
                                  Text(
                                      snapshot.data![index].jumlahSksSertifikat
                                          .toString(),
                                      style: regular6,
                                      textAlign: TextAlign.center)
                                ]),
                              ]),
                            ],
                          ),
                        ],
                      ),
                    ),
                  ),
                );
              },
            ),
          );
        }
        return Expanded(
          child: Center(
            child: CircularProgressIndicator(color: primaryColor),
          ),
        );
      },
    );
  }
}

i want to show list Mk my model

{
    "status": "created",
    "code": "201",
    "data": {
        "kurikulum": [
            {
                "id": "6c9c9b1b-6188-4080-aa82-a12149388ee4",
                "name": "SI20222",
                "id_semester": "7f5ad13e-ac75-46fb-8ada-562acec52570",
                "smt": "2022-2023 Genap",
                "id_prodi": "d4f99a8c-45c3-435b-a3b6-470679bba3bd",
                "jenjang": "S1",
                "prodi": "Sistem Informasi",
                "sks_wajib": 24,
                "sks_pilihan": 22,
                "total_sks": 46,
                "total_sks_wajib": "81",
                "total_sks_pilihan": 0,
                "total_sks_sertifikat": "4"
            }
        ],
        "mk": [
            {
                "id": "2b2e4042-3ae7-4632-a6e6-ac37e096f7c1",
                "id_kurikulum": "6c9c9b1b-6188-4080-aa82-a12149388ee4",
                "id_matkul": "d826ab00-fcbf-47c9-95da-9d2a8d628bee",
                "kode": "MU0507",
                "matakuliah": "Bahasa indonesia",
                "sks_tm": "2",
                "praktek": 0,
                "sks_pl": "0",
                "sks_sims": "0",
                "semester": 2,
                "wajib": "Wajib",
                "jumlah_sks_wajib": "2",
                "jumlah_sks_pilihan": 0,
                "jumlah_sks_sertifikat": 0,
                "created_by": "Yunita Sulistiani(2023-01-12 09:12:13)",
                "updated_by": "Yunita Sulistiani(2023-01-12 09:12:13)"
            },
            {
                "id": "28495057-40d3-4255-9da1-ecbcbae39a92",
                "id_kurikulum": "6c9c9b1b-6188-4080-aa82-a12149388ee4",
                "id_matkul": "63acd9d5-9873-4852-bf1a-3b7da133ffc8",
                "kode": "DK0511",
                "matakuliah": "Sistem operasi",
                "sks_tm": "3",
                "praktek": 0,
                "sks_pl": "0",
                "sks_sims": "0",
                "semester": 2,
                "wajib": "Wajib",
                "jumlah_sks_wajib": "3",
                "jumlah_sks_pilihan": 0,
                "jumlah_sks_sertifikat": 0,
                "created_by": "Yunita Sulistiani(2023-01-12 09:12:52)",
                "updated_by": "Yunita Sulistiani(2023-01-12 09:12:52)"
            },
            {
                "id": "53dffdf1-793c-41c0-9d6e-6b4e09c6d421",
                "id_kurikulum": "6c9c9b1b-6188-4080-aa82-a12149388ee4",
                "id_matkul": "bf063878-ab8a-4aad-b686-007a4e21d1b1",
                "kode": "MU0501",
                "matakuliah": "Kewirausahaan",
                "sks_tm": "2",
                "praktek": 0,
                "sks_pl": "0",
                "sks_sims": "0",
                "semester": 2,
                "wajib": "Wajib",
                "jumlah_sks_wajib": "2",
                "jumlah_sks_pilihan": 0,
                "jumlah_sks_sertifikat": 0,
                "created_by": "Yunita Sulistiani(2023-01-12 09:13:17)",
                "updated_by": "Yunita Sulistiani(2023-01-12 09:13:17)"
            }, ...

Answer 1

I see your future defination is null and never initialized.

Future<List<Mk>>? futureMk;

And you are using futureMk as a future in the FutureBuilder. As the futureMk is null, snapshot.hasData is never true.

---

Possible solution:

Change the future to the defined one, or define futureMk

FutureBuilder<List<Mk>>(
      future: getDetail(<your_id_here>), // I guess you are intending to use this future here and not futureMk
      builder: (context, snapshot) {
        if (snapshot.hasData) {
           // ListView Here
          ...
       }}