使用带颤振的rest API列出信息时出错

Question

我试图列出屏幕上剩余的应用编程接口的信息。我有这个方法：

late List<MyModel> _listAll; // original list fetched from API
late List<MyModel> _displayList; 
.
.

void _ListTransaction() async {
    
    SharedPreferences prefs = await SharedPreferences.getInstance();
    String token = prefs.getString("userToken") ?? "";

    dynamic data = await http.get(Uri.parse('....'), headers: {
      'Content-Type': 'application/json',
      'Accept': 'application/json',
      'Authorization': '$token',
    });
    
    List<MyModel> listAll= [];

    for (var u in data) {
      MyModel myModel = MyModel.fromJson(u);
      print(myModel);
      listAll.add(myModel);
    }

    setState(() {
      _listAll = listAll;
      _displayList = _listAll ;
    });
  }

这里我得到的错误：

_类型错误（类型“\u InternalLinkedHashMap

我也尝试过这种做法：

void _ListTransaction() async {

    SharedPreferences prefs = await SharedPreferences.getInstance();
    String token = prefs.getString("userToken") ?? "";

    dynamic data = await http.get(Uri.parse('....'), headers: {
      'Content-Type': 'application/json',
      'Accept': 'application/json',
      'Authorization': '$token',
    });

   var list = json.decode(data.body);
    print(list);

    setState(() {
      _listAll = list;
      _displayedList = _petrolList;
    });
    
  }

但这里我得到了一个错误：

_类型错误（类型“\u InternalLinkedHashMap

你们可以帮我解决这个错误。我感谢您的评论！

更新我也用过这种方法，但没有用！

我的模型：

class TransactionModel {
  int? month;
  int? year;
  double? balanceFull;
  double? balanceMonth;
  ExpenseModel? expenseModel;
  RevenueModel? revenueModel; 

  TransactionModel();

  Transactions() {
    month = 00;
    year = 0000;
    balanceFull = 0;
    balanceMonth = 0;
  }

  TransactionModel.fromJson(Map<String, dynamic> json) {
    month = json['month'];
    year = json['year'];
    balanceFull = json['balanceFull'];
    balanceMonth = json['balanceMonth'];
    expenseModel = json['expenseModel'];
    revenueModel = json['revenueModel'];
  }

Answer 1

上周我也有类似的问题。

我用下面的代码解决了这个问题：

  int _offset = 0;
  List<Skeleton> array_news = [];

  Future<List<Skeleton>> fetchNews(int offset) async {
    final response = await http.get(Uri.parse(
        'http://192.168.15.5:5000//custom-events?limit=3&offset=$offset'));

    return parseNews(response.body);
  }

  List<Skeleton> parseNews(String responseBody) {
    final parsed =
        json.decode(responseBody)['events'].cast<Map<String, dynamic>>();
    return parsed.map<Skeleton>((json) => Skeleton.fromJson(json)).toList();
  }

  void executeScript(int offset) async {
    List news = await fetchNews(offset);
    setState(() {
      news.forEach((data) {
        array_news.add(Skeleton(
            id: data.id,
            title: data.title,
            page_link: data.page_link,
            image_link: data.image_link));
      });
    });
  }

骨架代码：

class Skeleton {
  int id = 0;
  String title = '';
  String page_link = '';
  String image_link = '';

  Skeleton(
      {required this.id,
      required this.title,
      required this.page_link,
      required this.image_link});

  Skeleton.fromJson(Map<String, dynamic> json) {
    id = json['id'];
    title = json['title'];
    page_link = json['page_link'];
    image_link = json['image_link'];
  }

  Map<String, dynamic> toJson() {
    final Map<String, dynamic> data = new Map<String, dynamic>();
    data['id'] = this.id;
    data['title'] = this.title;
    data['page_link'] = this.page_link;
    data['image_link'] = this.image_link;
    return data;
  }
}

之后，只需通过索引访问array_news列表数据。

例如：

array_news[0].title;

Answer 2

你应该这样做：

var result = json.decode(data.body);
List<Map<String, dynamic>> list = (result as List).map((e) => e as Map<String, dynamic>).toList();
list.forEach((element) {
  _listAll.add(MyModel.fromJson(element));
}

在我的例子中，这是有效的，因为我有一个Map的列表

编辑：根据您的评论和屏幕截图，您应该执行以下操作：

Map<String, dynamic> result = json.decode(data.body) as Map<String, dynamic>;
result.forEach((element) {
  _listAll.add(MyModel.fromJson(element));
}

在交易模型中：

TransactionModel.fromJson(Map<String, dynamic> json) {
    month = json['month'];
    year = json['year'];
    balanceFull = json['balanceFull'];
    balanceMonth = json['balanceMonth'];
    List<Map<String, dynamic>> expenseList = (json["expenses"] as List).map((e) => e as Map<String, dynamic>).toList();
    List<Map<String, dynamic>> revenueList = (json["revenues"] as List).map((e) => e as Map<String, dynamic>).toList();
    expenseModel = ExpenseModel.fromJson(list.first) // You can loop
    revenueModel = RevenueModel.fromJson(revenueList.first) // Same
  }

这个想法是，您需要将每个嵌套模型转换为Map

不久前我也有过同样的经历。

Answer 3

我认为错误在于_listAll是MyModel的类型列表，但“setState”方法中的列表是Map

我希望能帮助你。