无法加载JSON数据以在ListView中显示

Question

我需要通过提供get方法来在flutter应用程序中获取json数组数据。

我面临的问题是我无法将记录放入空列表carList中。

但是我得到的对象数组如下图所示（POSTMAN）：>

print（json.decode（response.body））// // [在cars.dart文件中

因此，如果可以的话，请帮助我在

List carlist = [];

]中获取答复。Car_list.dart文件调用获取请求的方法。

如果您需要我提供的进一步信息，请告诉我。

谢谢

邮递员

[
{
"id": "1",
"carModel" : "Maruti swift",
"carDescription" : "The car has a top speed of 180 km/hr"
},
{
"id": "1",
"carModel" : "Hyundai santro",
"carDescription" : "The car has a top speed of 150 km/hr"
},
{
"id": "1",
"carModel" : "Hyundai creta",
"carDescription" : "The car has a top speed of 160 km/hr"
}
]

CarsModel.dart
class Cars with ChangeNotifier{
   String userId;
   String carModel
   String carDescription;


  Cars(
  {
    this.userId = '1111',
    this.carModel,
    this.carDescription,
  }
);

 factory Cars.fromJSON(Map<String,dynamic> json) => Cars(
     userId : json['userId'],
     carModel : json['CarModel'],
     carDescription : json['carDescription'],
 );


toJSON() {
  return {
    'userId':'111',
    'carModel':carModel,
    'carDescription' : carDescription
  };
}

cars.dart
class CarProvider with ChangeNotifier{

List<Cars> carlist = [
//Sample data to show the format in which the data needs to be shown as the listview gets populated from below records which we are supposed to get from postman 
//Cars (
//    userid: 1111,
//    carModel: 'Maruti Alto',
//    carDescription: 'Top speed 140 km/hr'


    ),
];

Future<void> readListofCars(int id) async {

 print(id.toString());


 const url = 'http://localhost/userlist';

// {'id': id.toString()

 Map<String, String> headers = {   
"Content-type": "application/json"};

try
  {
  final response = await http.get(url,headers: headers);

  List<dynamic> bodyCars = jsonDecode(response.body);

  List<Cars> loadedCars = bodyCars.map((dynamic item) => new Cars.fromJSON(item)).toList();


  /*
    for (Map i in bodyCars) {
    _notificationitems.add(Cars.fromJSON(i));
  }
 */

  });

 print(response.statusCode);
  carlist  = loadedCars; 
 print(json.decode(response.body));
 notifyListeners();

}catch (error){
  throw error;
}
}

Car_list.dart
class TabScreenCar extends StatefulWidget {

  final String userId;


  TabScreenCar(this.userId);

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

class _TabScreenCarState extends State<TabScreenCar> {
@override
void didChangeDependencies() {
   final id = 1111;
    Provider.of<CarProvider>(context).readListofCars(id);

  super.didChangeDependencies(); 
}

我需要通过提供get方法来在flutter应用程序中获取json数组数据。我面临的问题是我无法将记录放入空列表carList中。但我得到了...

Answer 1

在模型类中，您有错误的变量无法获取json数据

为了简化过程，您可以查看此链接