Parse nested json failed flutter - flutter

Question

I have this json response that contains servicetype,vehiclemodels,accessories,working status as array but i cannot access any of the class,when i print print(obj); it just shows null
Json file
{
"success": true,
"message": "",
"data": {
"service_types": [
{
"id": 1,
"name": "Car Wash"
},
{
"id": 2,
"name": "Full Body Wash"
},
{
"id": 3,
"name": "Polishing"
},
{
"id": 4,
"name": "Engine Oil Checkup"
},
],
"vehicle_models": [
{
"id": 1,
"name": "SUV"
}
],
"accessories": [
{
"id": 2,
"name": "Mat Cover"
},
{
"id": 4,
"name": "Cash"
},
{
"id": 5,
"name": "Engine Room washing"
}
],
"working_statuses": [
{
"id": 0,
"name": "Registered"
},
{
"id": 1,
"name": "Work started"
},
{
"id": 2,
"name": "Work completed"
},
{
"id": 5,
"name": "Cancelled"
}
]
}
}
Code for extracting data
var response = await http.post(Uri.parse(Urls.DasboardData),
headers: {"Content-Type": "application/json"},
body: json.encode({
"vehicle_models": "",
"service_types": "",
"station_id":Station_id,
"accessories": "",
"working_statuses": "",
}));
Map<String, dynamic> value = json.decode(response.body);
var data = value['data'];
if (data.length > 0) {
for (int i = 0; i < data.length; i++) {
var obj = data[i];
print(obj);
var service_type_obj = obj['service_types'];
var vehicle_models_obj = obj['vehicle_models'];
var accessories_obj = obj['accessories'];
var working_statuses_obj = obj['working_statuses'];
DataList.add(GetAllModel(
service_type_obj['id'],
service_type_obj['name'],
vehicle_models_obj['id'],
vehicle_models_obj['name'],
accessories_obj['id'],
accessories_obj['name'],
working_statuses_obj['id'],
working_statuses_obj['name'],
));
}
setState(() {
print("UI UPDATED");
});
}
else
{
}
Model
class GetAllModel {
String service_type_id,
service_type_name,
vehicle_models_id,
vehicle_models_name,
accessories_id,
accessories_name,
working_statuses_id,
working_statuses_name;
GetAllModel(
this.service_type_id,
this.service_type_name,
this.vehicle_models_id,
this.vehicle_models_name,
this.accessories_id,
this.accessories_name,
this.working_statuses_id,
this.working_statuses_name,
);
}

Answer 1

The problem is at the time of iterating your information, the data size is 4, but this It contains 4 objects, therefore you will not be able to access data[i] because data[i] does not exist, if it exists data ['service_types'] which is a list and here if you could iterate the information that this contains object.
So to be able to access the information of your objects you must iterate them like this:
for (var i = 0; i < data['service_types'].length; i++) {
print(data['service_types'][i]);
}
and the same for the other objects.
An alternative to iterate:
for (var item in data.values) {
print(item);
}

Answer 2

You need to change these:
var service_type_obj = obj['service_types'];
var vehicle_models_obj = obj['vehicle_models'];
var accessories_obj = obj['accessories'];
var working_statuses_obj = obj['working_statuses'];
into this:
var service_type_obj = obj['service_types'][0];
var vehicle_models_obj = obj['vehicle_models'][0];
var accessories_obj = obj['accessories'][0];
var working_statuses_obj = obj['working_statuses'][0];
You're objects are located inside a list, to access them, you have to use an index, like[0].