flutter : 嵌套的 json 解析列表

Posted 2023-02-23

【中文标题】flutter : 嵌套的 json 解析列表

【英文标题】：flutter : nested json parsing list

【发布时间】：2020-05-21 00:47:41

【问题描述】：

我正在尝试从我的 json 代码中调用名称和费用 它是我的 json 主数组中的嵌套数组，主数组我可以处理它，但子数组我不能

"guideExtraServices": [
      
        "Name": "Limousine",
        "Fees": 100
      ,
      
        "Name": "Bus",
        "Fees": 10000
      ,
      
        "Name": "Mini-Bus",
        "Fees": 5000
      
    ], 

我不能这样做，因为在我试图调用“姓名”和“费用”时出现错误

type 'List<ExtraServices>' is not a subtype of type 'String'

这是我的类，用于映射导游数据以在列表视图中使用它

class TourGuide
  String id;
  String name;
  String email;
  String password;
  List<ExtraServices> extraService;

  TourGuide(
      this.id,
      this.name,
      this.email,
      this.password,
    this.extraService,
  );

  TourGuide.fromJson(Map<String, dynamic> json)
    List<dynamic> extra = json['guideExtraServices'];
    List<ExtraServices> extraList = extra.map((i) => ExtraServices.fromJson(i)).toList();
id = json['id'].toString();
name = json['displayName'];
email = json['email'];
password = json['password'];
    extraService=extraList;
  

这是一个额外的服务类，导游类依赖它来获取子数组

   class ExtraServices
      String name;
      double fees;
      ExtraServices(
        this.name,
        this.fees
      );

      ExtraServices.fromJson(Map<String, dynamic> json)
        name = json['Name'];
        fees = json['Fees'].toDouble();
      
    

我使用 api 解码 json 的提供者方法

 Future<dynamic> tourGuideList() async 
        _isLoading = true;
        notifyListeners();
        print('Starting request');

        http.Response response = await http.get(Environment.tourGuide,
            headers: Environment.requestHeader);
        print('Completed request');
        print('respond data : $response.body');

        Map<String, dynamic> res = json.decode(response.body);
        var results;
        if (res['code'] == 200) 

          print('start load tourguide');
          _tourGuide = [];
          res['message'].forEach((v) 
            _tourGuide.add(new TourGuide.fromJson(v));  
          ); 

          results = true;
         else 
          results =
              FailedRequest(code: 400, message: res['error'], status: false);
        
        _isLoading = false;
        notifyListeners();
        return results;
      

我不知道为什么我有一个错误，我无法修复它

【问题讨论】：

查看这个高级 JSON 解析示例。 ***.com/a/60224846/3756408

【参考方案1】：

请尝试以下代码：-

首先创建模型：-

class GuideResponseModel 
  List<GuideExtraServicesModel> guideExtraServiceList;

  GuideResponseModel(
    this.guideExtraServiceList
  );

  factory GuideResponseModel.fromJson(Map<String, dynamic> parsedJson) 
    try 
      List<GuideExtraServicesModel> guideExtraServiceModelList = new List();

      if (parsedJson.containsKey('guideExtraServices')) 
        var countryList = parsedJson['guideExtraServices'] as List;
        guideExtraServiceModelList =
            countryList.map((i) => GuideExtraServicesModel.fromJson(i)).toList();
      

      return GuideResponseModel(
        guideExtraServiceList: guideExtraServiceModelList
      );
     catch (e) 
      return null;
    
  

class GuideExtraServicesModel 
  String name;
  int fees;

  GuideExtraServicesModel(this.name,this.fees);

  factory GuideExtraServicesModel.fromJson(Map<String, dynamic> json) 
    return GuideExtraServicesModel(name: json['Name'],fees: json['Fees']);
  

模型的第二个用户：-

String jsonData = '"guideExtraServices": ["Name": "Limousine","Fees": 100,"Name": "Bus","Fees": 10000,"Name": "Mini-Bus","Fees": 5000]';
final dynamic jsonResponse = json.decode(jsonData);
final GuideResponseModel responseModel = GuideResponseModel.fromJson(jsonResponse);
print('======$responseModel.guideExtraServiceList[0].name----$responseModel.guideExtraServiceList[0].fees');

【参考方案2】：

我觉得你的json总共应该是这样的：

"guideExtraServices": [
      
        "Name": "Limousine",
        "Fees": 100
      ,
      
        "Name": "Bus",
        "Fees": 10000
      ,
      
        "Name": "Mini-Bus",
        "Fees": 5000
      
    ]

试试

// To parse this JSON data, do
//
//     final tourGuide = tourGuideFromJson(jsonString);

import 'dart:convert';

TourGuide tourGuideFromJson(String str) => TourGuide.fromJson(json.decode(str));

String tourGuideToJson(TourGuide data) => json.encode(data.toJson());

class TourGuide 
    List<GuideExtraService> guideExtraServices;

    TourGuide(
        this.guideExtraServices,
    );

    factory TourGuide.fromJson(Map<String, dynamic> json) => TourGuide(
        guideExtraServices: List<GuideExtraService>.from(json["guideExtraServices"].map((x) => GuideExtraService.fromJson(x))),
    );

    Map<String, dynamic> toJson() => 
        "guideExtraServices": List<dynamic>.from(guideExtraServices.map((x) => x.toJson())),
    ;


class GuideExtraService 
    String name;
    int fees;

    GuideExtraService(
        this.name,
        this.fees,
    );

    factory GuideExtraService.fromJson(Map<String, dynamic> json) => GuideExtraService(
        name: json["Name"],
        fees: json["Fees"],
    );

    Map<String, dynamic> toJson() => 
        "Name": name,
        "Fees": fees,
    ;

【讨论】：

先生，你为什么写这部分代码 Map toJson() => "guideExtraServices": List.from(guideExtraServices.map((x) => x.toJson())), ;

它只是一个完整的类来实现 Json 和 Json。您永远不知道何时需要转换器。目前尝试 final tourGuide = tourGuideFromJson(jsonString);

我会贴出我的方法，你可以看看吗？

我现在添加了，先生

你能发布完整的 json 响应吗？有没有属性码是200的？