我想在flutter中從api獲取json

class Phone{
int? id;
bool? is_new;
String? title;
String? subtitle;
String? picture;
bool? is_buy;
dynamic best_seller;
int? price_without_discount;
int? discount_price;

Phone({
  this.id,
  this.is_new,
  this.title,
  this.subtitle,
  this.picture,
  this.is_buy,
  this.best_seller,
  this.price_without_discount,
  this.discount_price
});
 factory Phone.fromJson(Map <String, dynamic> json) => Phone(
     id: json[MyPhoneKeys.id],
     is_new: json[MyPhoneKeys.is_new],
     title: json[MyPhoneKeys.title],
     subtitle: json[MyPhoneKeys.subtitle],
     picture: json[MyPhoneKeys.picture],
     is_buy: json[MyPhoneKeys.is_buy],
     best_seller: json[MyPhoneKeys.best_seller],
     price_without_discount: json[MyPhoneKeys.price_without_discount],
     discount_price: json[MyPhoneKeys.discount_price]
 );
}

（我的螢屏顯示資料）

class CarouselSliderData extends StatefulWidget{
  const CarouselSliderData({super.key});


  @override
  State<CarouselSliderData> createState() => CarouselSliderDataState();
}

class CarouselSliderDataState extends State<CarouselSliderData> {
  int? id;
  bool? is_new;
  String? title;
  String? subtitle;
  dynamic picture;
  bool? is_buy;
  dynamic best_seller;
  int? price_without_discount;
  int? discount_price;

  late Future<dynamic> phoneSpec;

  @override
  void initState() {
    phoneSpec = MyApiService().getDataMocky();
    super.initState();
  }


  @override
  Widget build(BuildContext context) {
     return FutureBuilder<dynamic>(
          future: phoneSpec,
          builder: (context, snapshot) {
              return Column(
                mainAxisAlignment: MainAxisAlignment.center,
                crossAxisAlignment: CrossAxisAlignment.center,
                children: [
                  Text(snapshot.data!.id),
                  Text(snapshot.data!.is_new),
                  Text(snapshot.data!.title),
                  Text(snapshot.data!.subtitle),
                  Text(snapshot.data!.picture),
                  Text(snapshot.data!.is_buy),
                  Text(snapshot.data!.best_seller),
                  Text(snapshot.data!.price_without_discount),
                  Text(snapshot.data!.discount_price),
                ],
              );

          }



          );
  }

  Future<dynamic> getData() async{
    return await MyApiService().getDataMocky().then((value) async{
      if(value != null){
        setState((){
          id = value!.id!;
          is_new = value!.is_new!;
          title = value!.title!;
          subtitle = value!.subtitle!;
          picture = value!.picture!;
         is_buy = value!.is_buy!;
          best_seller = value!.best_seller!;
          price_without_discount = value!.price_without_discount!;
          discount_price = value!.discount_price!;

        });
        return value;
      }
    },
    );/*.catchError((_){
     throw Exception("Exception is caught");
   });*/
  }
}

（我獲取資料的服務）

import 'dart:convert';
import 'package:http/http.dart' as http;
import 'package:my_work/apiService/model.dart';


class MyApiService{

  Future<dynamic> getDataMocky() async {
  final response = await http.get(
    Uri.parse('https://run.mocky.io/v3/654bd15e-b121-49ba-a588-960956b15175')
  );

  if(response.statusCode == 200){
    return Phone.fromJson(json.decode(response.body)[1]);
  }
  return Exception();
  }
}

我的模型是否適合來自這個 api的這個 api json 。我想獲取資料并將它們顯示在輪播滑塊中（我將添加它）但得到空值。錯誤在說Null is not subtype of String and nullcheck is used on NULL value，我不知道為什么以及我的錯誤在哪里。非常感謝

uj5u.com熱心網友回復：

Text小部件不接受可為空的字串。

與其使用!它，不如先檢查 null，或者您可以在 null 情況下提供默認值。格式會像

if(snapshot.data!=null) Text(snapshot.data.id),

或者

Text(snapshot.data?.id??"got null"),

或者使用像下面這樣的字串格式，它會在 null 情況下顯示 null。

Text("${snapshot.data?.id}"),

我會建議檢查理解零安全性

標籤：json扑api镖飞镖零安全

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