Flutter '_内部链接dhashmap<；字符串，动态>'；没有实例方法'；铸造'；具有匹配参数_Flutter_Dart

Flutter '_内部链接dhashmap<；字符串，动态>'；没有实例方法'；铸造'；具有匹配参数

flutter dart

Flutter '_内部链接dhashmap<；字符串，动态>'；没有实例方法'；铸造'；具有匹配参数,flutter,dart,Flutter,Dart,每次运行时 import 'dart:convert'; import 'package:http/http.dart' as http; import 'package:rona/Models/Global_model.dart'; class NetworkHelper { static const String url = 'https://covid-193.p.rapidapi.com/statistics'; static List<GlobalDataModel&

每次运行时

import 'dart:convert';
import 'package:http/http.dart' as http;
import 'package:rona/Models/Global_model.dart';

class NetworkHelper {
  static const String url = 'https://covid-193.p.rapidapi.com/statistics';

  static List<GlobalDataModel> parse(String responseBody) {
    final parsed = json.decode(responseBody).cast<Map<String, dynamic>>();
    return parsed
        .map<GlobalDataModel>((json) => GlobalDataModel.fromMap(json))
        .toList();
  }

  static Future<List<GlobalDataModel>> getGlobalData() async {
    try {
      final response = await http.get(url, headers: {
        "x-rapidapi-host": "covid-193.p.rapidapi.com",
        "x-rapidapi-key": "1d2e200e8amsh264b6230392cdfcp119d06jsn3f9a7a0e8fd0",
        "useQueryString": "true"
      });
      if (response.statusCode == 200) {
        List<GlobalDataModel> list = parse(response.body);
        return list;
      } else {
        throw Exception("Error");
      }
    } catch (e) {
      throw Exception(e.toString());
    }
  }
}

请帮帮我，我已经做了一段时间了

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您向

cast

提供的类型参数不正确。您可以为它提供所需的键和值的类型参数，而不是

映射本身的类型参数：
final parsed=json.decode（responseBody.cast（）；

不过，对于转换后的JSON字符串，使用as
运算符执行普通转换通常是安全的：
final parsed=json.decode（responseBody）作为映射；

或者通过给parsed
一个显式类型来执行隐式强制转换：
final Map parsed=json.decode（responseBody）；
您可以复制粘贴运行下面的完整代码

要返回List
，可以使用List.from（已解析的[“响应”]


代码片段
static List<GlobalDataModel> parse(String responseBody) {
    final Map<String, dynamic> parsed = json.decode(responseBody);

    return List<GlobalDataModel>.from(
        parsed["response"].map((x) => GlobalDataModel.fromJson(x)));
  }
...  
factory GlobalDataModel.fromJson(Map<String, dynamic> map) {
    return GlobalDataModel(
      continent: map['continent'] as String,
      country: map['country'] as String,
      population: map['population'] as int,
      activeCases: map['cases']['active'] as int,
      criticalCases: map['cases']['critical'] as int,
      recovered: map['cases']['recovered'] as int,
      totalCases: map['cases']['total'] as int,
      totalDeaths: map['deaths']['total'] as int,
    );

静态列表解析（字符串响应库）{
解析的最终映射=json.decode（responseBody）；
返回列表。从(
解析的[“response”].map（（x）=>GlobalDataModel.fromJson（x））；
}
...  
factory GlobalDataModel.fromJson（映射）{
返回全局数据模型(
大陆：地图[‘大陆’]为字符串，
国家：地图['country']作为字符串，
人口：地图['population']为整数，
activeCases：将['cases']['active']映射为int，
临界值：将['cases']['critical']映射为int，
已恢复：将['cases']['recovered']映射为int，
totalCases:将['cases']['total']映射为int，
TotalDeathers:map['Deathers']['total']为整数，
);

工作演示

完整代码
import 'package:flutter/material.dart';
import 'dart:convert';
import 'package:http/http.dart' as http;

class NetworkHelper {
  static const String url = 'https://covid-193.p.rapidapi.com/statistics';

  static List<GlobalDataModel> parse(String responseBody) {
    final Map<String, dynamic> parsed = json.decode(responseBody);

    return List<GlobalDataModel>.from(
        parsed["response"].map((x) => GlobalDataModel.fromJson(x)));
  }

  static Future<List<GlobalDataModel>> getGlobalData() async {
    try {
      final response = await http.get(url, headers: {
        "x-rapidapi-host": "covid-193.p.rapidapi.com",
        "x-rapidapi-key": "1d2e200e8amsh264b6230392cdfcp119d06jsn3f9a7a0e8fd0",
        "useQueryString": "true"
      });
      if (response.statusCode == 200) {
        print(response.body);
        List<GlobalDataModel> list = parse(response.body);
        return list;
      } else {
        throw Exception("Error");
      }
    } catch (e) {
      throw Exception(e.toString());
    }
  }
}

class GlobalDataModel {
  String continent;
  String country;
  int population;
  int activeCases;
  int criticalCases;
  int totalCases;
  int recovered;
  int totalDeaths;

  GlobalDataModel({
    this.continent,
    this.country,
    this.population,
    this.activeCases,
    this.criticalCases,
    this.recovered,
    this.totalCases,
    this.totalDeaths,
  });

  Future<dynamic> getGlobalData() async {
    await NetworkHelper.getGlobalData().then((data) {
      print('Data: ${data.length}');
    });
  }

  factory GlobalDataModel.fromJson(Map<String, dynamic> map) {
    return GlobalDataModel(
      continent: map['continent'] as String,
      country: map['country'] as String,
      population: map['population'] as int,
      activeCases: map['cases']['active'] as int,
      criticalCases: map['cases']['critical'] as int,
      recovered: map['cases']['recovered'] as int,
      totalCases: map['cases']['total'] as int,
      totalDeaths: map['deaths']['total'] as int,
    );
  }
}

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
        visualDensity: VisualDensity.adaptivePlatformDensity,
      ),
      home: MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);

  final String title;

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

class _MyHomePageState extends State<MyHomePage> {
  Future<List<GlobalDataModel>> _future;

  @override
  void initState() {
    _future = NetworkHelper.getGlobalData();
    super.initState();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
        appBar: AppBar(
          title: Text(widget.title),
        ),
        body: FutureBuilder(
            future: _future,
            builder: (context, AsyncSnapshot<List<GlobalDataModel>> snapshot) {
              switch (snapshot.connectionState) {
                case ConnectionState.none:
                  return Text('none');
                case ConnectionState.waiting:
                  return Center(child: CircularProgressIndicator());
                case ConnectionState.active:
                  return Text('');
                case ConnectionState.done:
                  if (snapshot.hasError) {
                    return Text(
                      '${snapshot.error}',
                      style: TextStyle(color: Colors.red),
                    );
                  } else {
                    return ListView.builder(
                        itemCount: snapshot.data.length,
                        itemBuilder: (context, index) {
                          return Card(
                              elevation: 6.0,
                              child: Padding(
                                padding: const EdgeInsets.only(
                                    top: 6.0,
                                    bottom: 6.0,
                                    left: 8.0,
                                    right: 8.0),
                                child: Row(
                                  crossAxisAlignment: CrossAxisAlignment.start,
                                  children: <Widget>[
                                    Text(snapshot.data[index].country
                                        .toString()),
                                    Spacer(),
                                    Text(snapshot.data[index].totalCases
                                        .toString()),
                                  ],
                                ),
                              ));
                        });
                  }
              }
            }));
  }
}

导入“包装：颤振/材料.省道”；
导入“dart:convert”；
将“package:http/http.dart”导入为http；
类NetworkHelper{
静态常量字符串url=https://covid-193.p.rapidapi.com/statistics';
静态列表解析（字符串响应库）{
解析的最终映射=json.decode（responseBody）；
返回列表。从(
解析的[“response”].map（（x）=>GlobalDataModel.fromJson（x））；
}
静态未来getGlobalData（）异步{
试一试{
最终响应=等待http.get（url，标题：{
“x-rapidapi-host”：“covid-193.p.rapidapi.com”，
“x-rapidapi-key”：“1D2E2200E8AMSH264B6230392CDFCP119D06JSN3F9A7A0E8FD0”，
“useQueryString”：“true”
});
如果（response.statusCode==200）{
打印（响应.正文）；
List=parse（response.body）；
退货清单；
}否则{
抛出异常（“错误”）；
}
}捕获（e）{
抛出异常（例如toString（））；
}
}
}
类全局数据模型{
弦大陆；
弦国；
国际人口；
国际案例；
int临界值；
总病例数；
int恢复；
总死亡人数；
全局数据模型({
这个大陆，
这个国家，
这个人口,，
这两个案例，
这一点至关重要，
这个,恢复了,，
这个,这个案例,，
这是死亡总数，
});
未来的getGlobalData（）异步{
等待NetworkHelper.getGlobalData（）。然后（（数据）{
打印（'Data:${Data.length}'）；
});
}
factory GlobalDataModel.fromJson（映射）{
返回全局数据模型(
大陆：地图[‘大陆’]为字符串，
国家：地图['country']作为字符串，
人口：地图['population']为整数，
activeCases：将['cases']['active']映射为int，
临界值：将['cases']['critical']映射为int，
已恢复：将['cases']['recovered']映射为int，
totalCases:将['cases']['total']映射为int，
TotalDeathers:map['Deathers']['total']为整数，
);
}
}
void main（）{
runApp（MyApp（））；
}
类MyApp扩展了无状态小部件{
@凌驾
小部件构建（构建上下文）{
返回材料PP(
标题：“颤振演示”，
主题：主题数据(
主样本：颜色。蓝色，
视觉密度：视觉密度。自适应平台密度，
),
主页：MyHomePage（标题：“颤振演示主页”），
);
}
}
类MyHomePage扩展StatefulWidget{
MyHomePage（{Key，this.title}）：超级（Key:Key）；
最后的字符串标题；
@凌驾
_MyHomePageState createState（）=>\u MyHomePageState（）；
}
类_MyHomePageState扩展状态{
未来,未来;；
@凌驾
void initState（）{
_future=NetworkHelper.getGlobalData（）；
super.initState（）；
}
@凌驾
小部件构建（构建上下文）{
返回脚手架(
appBar:appBar(
标题：文本（widget.title），
),
正文：未来建设者(
未来：未来，
生成器：（上下文，异步快照）{
交换机（快照.连接状态）{
案例连接状态。无：
返回文本（“无”）；
案例连接状态。正在等待：
返回中心（子项：CircularProgressIndicator（））；
案例连接状态.active：
返回文本（“”）；
案例连接状态。完成：
if（snapshot.hasError）{
返回文本(
“${snapshot.error}”，
样式：TextStyle（颜色：Colors.red），
);
}否则{
返回ListView.builder(
itemCount:snapshot.data.length，
itemBuilder：（上下文，索引）{
回程卡(
标高：6.0，
孩子：填充(
填充：仅限常量边设置(
排名：6.0，
底部：6.0，
左：8.0，
{
  "get": "statistics",
  "parameters": [],
  "errors": [],
  "results": 227,
  "response": [
    {
      "continent": "Asia",
      "country": "China",
      "population": 1439323776,
      "cases": {
        "new": "+9",
        "active": 244,
        "critical": 5,
        "recovered": 80153,
        "1M_pop": "59",
        "total": 85031
      },
      "deaths": {
        "new": null,
        "1M_pop": "3",
        "total": 4634
      },
      "tests": {
        "1M_pop": "62814",
        "total": 90410000
      },
      "day": "2020-08-30",
      "time": "2020-08-30T17:00:11+00:00"
    },
    {
      "continent": "Europe",
      "country": "Italy",
      "population": 60447003,
      "cases": {
        "new": "+1365",
        "active": 24205,
        "critical": 86,
        "recovered": 208536,
        "1M_pop": "4437",
        "total": 268218
      },
      "deaths": {
        "new": "+4",
        "1M_pop": "587",
        "total": 35477
      },
      "tests": {
        "1M_pop": "142130",
        "total": 8591341
      },
      "day": "2020-08-30",
      "time": "2020-08-30T17:00:11+00:00"
    },
    {
      "continent": "Europe",
      "country": "Spain",
      "population": 46757684,
      "cases": {
        "new": "+3829",
        "active": 0,
        "critical": 751,
        "recovered": 0,
        "1M_pop": "9744",
        "total": 455621
      },
      "deaths": {
        "new": "+15",
        "1M_pop": "620",
        "total": 29011
      },
      "tests": {
        "1M_pop": "182161",
        "total": 8517446
      },
      "day": "2020-08-30",
      "time": "2020-08-30T17:00:11+00:00"
    }]

static List<GlobalDataModel> parse(String responseBody) {
    final Map<String, dynamic> parsed = json.decode(responseBody);

    return List<GlobalDataModel>.from(
        parsed["response"].map((x) => GlobalDataModel.fromJson(x)));
  }
...  
factory GlobalDataModel.fromJson(Map<String, dynamic> map) {
    return GlobalDataModel(
      continent: map['continent'] as String,
      country: map['country'] as String,
      population: map['population'] as int,
      activeCases: map['cases']['active'] as int,
      criticalCases: map['cases']['critical'] as int,
      recovered: map['cases']['recovered'] as int,
      totalCases: map['cases']['total'] as int,
      totalDeaths: map['deaths']['total'] as int,
    );

import 'package:flutter/material.dart';
import 'dart:convert';
import 'package:http/http.dart' as http;

class NetworkHelper {
  static const String url = 'https://covid-193.p.rapidapi.com/statistics';

  static List<GlobalDataModel> parse(String responseBody) {
    final Map<String, dynamic> parsed = json.decode(responseBody);

    return List<GlobalDataModel>.from(
        parsed["response"].map((x) => GlobalDataModel.fromJson(x)));
  }

  static Future<List<GlobalDataModel>> getGlobalData() async {
    try {
      final response = await http.get(url, headers: {
        "x-rapidapi-host": "covid-193.p.rapidapi.com",
        "x-rapidapi-key": "1d2e200e8amsh264b6230392cdfcp119d06jsn3f9a7a0e8fd0",
        "useQueryString": "true"
      });
      if (response.statusCode == 200) {
        print(response.body);
        List<GlobalDataModel> list = parse(response.body);
        return list;
      } else {
        throw Exception("Error");
      }
    } catch (e) {
      throw Exception(e.toString());
    }
  }
}

class GlobalDataModel {
  String continent;
  String country;
  int population;
  int activeCases;
  int criticalCases;
  int totalCases;
  int recovered;
  int totalDeaths;

  GlobalDataModel({
    this.continent,
    this.country,
    this.population,
    this.activeCases,
    this.criticalCases,
    this.recovered,
    this.totalCases,
    this.totalDeaths,
  });

  Future<dynamic> getGlobalData() async {
    await NetworkHelper.getGlobalData().then((data) {
      print('Data: ${data.length}');
    });
  }

  factory GlobalDataModel.fromJson(Map<String, dynamic> map) {
    return GlobalDataModel(
      continent: map['continent'] as String,
      country: map['country'] as String,
      population: map['population'] as int,
      activeCases: map['cases']['active'] as int,
      criticalCases: map['cases']['critical'] as int,
      recovered: map['cases']['recovered'] as int,
      totalCases: map['cases']['total'] as int,
      totalDeaths: map['deaths']['total'] as int,
    );
  }
}

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
        visualDensity: VisualDensity.adaptivePlatformDensity,
      ),
      home: MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);

  final String title;

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

class _MyHomePageState extends State<MyHomePage> {
  Future<List<GlobalDataModel>> _future;

  @override
  void initState() {
    _future = NetworkHelper.getGlobalData();
    super.initState();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
        appBar: AppBar(
          title: Text(widget.title),
        ),
        body: FutureBuilder(
            future: _future,
            builder: (context, AsyncSnapshot<List<GlobalDataModel>> snapshot) {
              switch (snapshot.connectionState) {
                case ConnectionState.none:
                  return Text('none');
                case ConnectionState.waiting:
                  return Center(child: CircularProgressIndicator());
                case ConnectionState.active:
                  return Text('');
                case ConnectionState.done:
                  if (snapshot.hasError) {
                    return Text(
                      '${snapshot.error}',
                      style: TextStyle(color: Colors.red),
                    );
                  } else {
                    return ListView.builder(
                        itemCount: snapshot.data.length,
                        itemBuilder: (context, index) {
                          return Card(
                              elevation: 6.0,
                              child: Padding(
                                padding: const EdgeInsets.only(
                                    top: 6.0,
                                    bottom: 6.0,
                                    left: 8.0,
                                    right: 8.0),
                                child: Row(
                                  crossAxisAlignment: CrossAxisAlignment.start,
                                  children: <Widget>[
                                    Text(snapshot.data[index].country
                                        .toString()),
                                    Spacer(),
                                    Text(snapshot.data[index].totalCases
                                        .toString()),
                                  ],
                                ),
                              ));
                        });
                  }
              }
            }));
  }
}