How to make search FLUTTER JSON - flutter

Question

I'm a new Flutter user, here I'm having a problem, I'm confused about how to make a search that reads from JSON, here I've created a search menu but I don't understand how to connect to the database. Can you help me to modify my source code so I can do a search. Hopefully good friends can help me make a search function. Thank you friend
datanasabah.dart
GlobalKey<ScaffoldState> _scaffoldState = GlobalKey<ScaffoldState>();
class DataNasabah extends StatefulWidget {
DataNasabah({Key key}) : super(key: key);
final String title = "Data Nasabah";
#override
_DataNasabahState createState() => _DataNasabahState();
}
class _DataNasabahState extends State<DataNasabah> {
ApiService apiService;
ListNasabah _listNasabah;
bool _isLoading = true;
List<Nasabah> data;
final _textHeadStyle =
TextStyle(color: Colors.white, fontSize: 18, fontWeight: FontWeight.bold);
void fetchData() async {
final res = await apiService.getNasabah();
data = res;
setState(() {
_isLoading = false;
});
}
#override
void initState() {
super.initState();
apiService = ApiService();
_listNasabah = new ListNasabah(apiService: apiService);
fetchData();
}
#override
Widget build(BuildContext context) {
return Scaffold(
key: _scaffoldState,
appBar: AppBar(
title: Text(
'Data Nasabah',
style: TextStyle(color: Colors.white),
),
actions: <Widget>[
MaterialButton(
elevation: 5,
child: Text("CARI", style: _textHeadStyle),
onPressed: () async {
var value = await showTopModalSheet<String>(
context: context, child: DumyModal());
},
),
],
),
body: _listNasabah.createViewList(),
);
}
}
class DumyModal extends StatelessWidget {
#override
Widget build(BuildContext context) {
return Container(
color: Colors.white,
height: MediaQuery.of(context).size.height * .2,
child: Column(
mainAxisAlignment: MainAxisAlignment.spaceEvenly,
crossAxisAlignment: CrossAxisAlignment.stretch,
children: <Widget>[
TextField(
decoration: InputDecoration(
labelText: "NIK Nasabah", //babel text
hintText: "Masukkan NIK Nasabah", //hint text
prefixIcon: Icon(Icons.people), //prefix iocn
hintStyle: TextStyle(fontSize: 18, fontWeight: FontWeight.bold, ), //hint text style
labelStyle: TextStyle(fontSize: 17, color: Colors.black), //label style
)
),
MaterialButton(
color: Colors.orange,
child: const Text("Cari", style: TextStyle(color: Colors.white),),
onPressed: () {
FocusScope.of(context).requestFocus(FocusNode());
},
)
],
),
);
}
}
nasabah_service.dart
class ApiService {
final String baseUrl = '192.168.100.207:8080';
Client client = Client();
Future<List<Nasabah>> getNasabah() async {
final response = await client.get('http://$baseUrl/api/mstdebitur');
print(response.body);
if (response.statusCode == 200) {
final nasabah = (json.decode(response.body) as List)
.map((e) => Nasabah.fromMap(e))
.toList();
return nasabah;
} else {
throw Exception('Failed to load post');
}
}
Future<bool> createNasabah(Nasabah data) async {
String url = new Uri.http("$baseUrl", "/api/mstdebitur/").toString();
final response = await client.post(url,
headers: {"Content-Type": "application/json"},
body: nasabahToJson(data));
if (response.statusCode == 201) {
return true;
} else {
return false;
}
}
Future<bool> updateNasabah(Nasabah data) async {
String url =
new Uri.http("$baseUrl", "/api/mstdebitur/${data.id}").toString();
final response = await client.put(url,
headers: {"Content-Type": "application/json"},
body: nasabahToJson(data));
if (response.statusCode == 200) {
return true;
} else {
return false;
}
}
Future<bool> deleteNasabah(int id) async {
String url = new Uri.http("$baseUrl", "/api/mstdebitur/$id").toString();
final response = await client.delete(url);
if (response.statusCode == 200) {
return true;
} else {
return false;
}
}
}