Flutter 未处理的异常:类型'_内部链接dhashmap<;字符串,动态>';不是类型为';Iterable<;动态>';
我正在尝试从API获取数据。端点中的示例数据如下所示:Flutter 未处理的异常:类型'_内部链接dhashmap<;字符串,动态>';不是类型为';Iterable<;动态>';,flutter,Flutter,我正在尝试从API获取数据。端点中的示例数据如下所示: `{4 items "error":false "statusCode":200 "message":"OK" "data":{2 items "lastChecked":"2020-04-02T11:49:38.233Z" "covid19Stats":[15 items 0:{8 items "city":"" "province":"Alberta" "country":"Canada" "lastUpdate":"2020-04-0
`{4 items
"error":false
"statusCode":200
"message":"OK"
"data":{2 items
"lastChecked":"2020-04-02T11:49:38.233Z"
"covid19Stats":[15 items
0:{8 items
"city":""
"province":"Alberta"
"country":"Canada"
"lastUpdate":"2020-04-01 22:04:44"
"keyId":"Alberta, Canada"
"confirmed":754
"deaths":9
"recovered":0
}
1:{...}8 items
2:{...}8 items
3:{...}8 items
4:{...}8 items
5:{...}8 items
6:{...}8 items
7:{...}8 items
8:{...}8 items
9:{...}8 items
10:{...}8 items
11:{...}8 items
12:{...}8 items
13:{...}8 items
14:{...}8 items
]
}
}`
我正在尝试将此数据映射到以下代码中的CovidData
类:
import 'dart:convert';
import 'package:flutter/material.dart';
import 'package:http/http.dart' as http;
class StatusPage extends StatefulWidget{
@override
State<StatefulWidget> createState() {
return StatusPageState();
}
}
class StatusPageState extends State<StatusPage>{
@override
void initState() {
super.initState();
fetch();
}
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Center(
child: Text(
"COVID-19 Stats",
style: TextStyle(
color: Colors.white,
fontFamily: 'Montserrat',
fontWeight: FontWeight.bold),
),
),
),
body: Container(
child: FlatButton(onPressed: () => show(), child: Text("Fetch")),
),
);
}
fetch(){
API.getStats().then(
(response) => {
lists = json.decode(response.body),
countries = lists.map((model) => CovidData.fromJson(model)).toList(),
// print(json.decode(response.body)['data']['covid19Stats'][0])
}
);
setState(() {
});
}
}
class CovidData{
String city = "";
String province = "";
String country = "";
String lastUpdate = "";
String keyId = "";
int confirmed = 0;
int deaths = 0;
int recovered = 0;
CovidData(String city, String province, String country, String lastUpdate, String keyId, int confirmed, int deaths, int recovered){
this.city = city;
this.province = province;
this.country = country;
this.lastUpdate = lastUpdate;
this.keyId = keyId;
this.confirmed = confirmed;
this.deaths = deaths;
this.recovered = recovered;
}
CovidData.fromJson(Map json)
: city = json['city'],
province = json['province'],
country = json['country'],
lastUpdate = json['lastUpdate'],
keyId = json['keyId'],
confirmed = json['confirmed'],
deaths = json['deaths'],
recovered = json['recovered'];
Iterable toJson(){
return [
{'city': city},
{'province': province},
{'country': country},
{'lastUpdate': lastUpdate},
{'keyId': keyId},
{'confirmed': confirmed},
{'deaths': deaths},
{'recovered': recovered},
];
}
}
List<CovidData> countries = [];
Iterable lists;
show(){
print(countries);
}
const baseUrl = "https://covid-19-coronavirus-statistics.p.rapidapi.com/v1/stats";
class API {
static Future getStats(){
return http.get(baseUrl, headers: {
"x-rapidapi-host": "covid-19-coronavirus-statistics.p.rapidapi.com",
"x-rapidapi-key": "8ca140a965mshe408a2e58737ba5p14b104jsn19a57561ec85"
});
}
}
导入'dart:convert';
进口“包装:颤振/材料.省道”;
将“package:http/http.dart”导入为http;
类StatusPage扩展StatefulWidget{
@凌驾
状态createState(){
返回StatusPageState();
}
}
类StatusPageState扩展状态{
@凌驾
void initState(){
super.initState();
fetch();
}
@凌驾
小部件构建(构建上下文){
返回脚手架(
appBar:appBar(
标题:中心(
子:文本(
“新冠病毒-19统计数据”,
样式:TextStyle(
颜色:颜色,白色,
fontFamily:“蒙特塞拉特”,
fontWeight:fontWeight.bold),
),
),
),
主体:容器(
子:扁平按钮(按下时:()=>show(),子:文本(“提取”),
),
);
}
fetch(){
API.getStats()。然后(
(回应)=>{
lists=json.decode(response.body),
countries=lists.map((model)=>CovidData.fromJson(model)).toList(),
//打印(json.decode(response.body)['data']['covid19Stats'][0])
}
);
设置状态(){
});
}
}
类CovidData{
字符串城市=”;
字符串“=”;
字符串country=“”;
字符串lastUpdate=“”;
字符串keyId=“”;
int=0;
int死亡=0;
int=0;
CovidData(字符串城市、字符串省、字符串国家、字符串最新更新、字符串密钥ID、整数确认、整数死亡、整数恢复){
this.city=城市;
这个省=省;
这个国家=国家;
this.lastUpdate=lastUpdate;
this.keyId=keyId;
这个.已确认的=已确认的;
死亡=死亡;
这个.恢复了=恢复了;
}
CovidData.fromJson(映射json)
:city=json['city'],
省=json['province'],
country=json['country'],
lastUpdate=json['lastUpdate'],
keyId=json['keyId'],
确认=json['confirm'],
Deathers=json['Deathers'],
recovered=json['recovered'];
Iterable toJson(){
返回[
{'city':city},
{'province':省},
{'country':country},
{'lastUpdate':lastUpdate},
{'keyId':keyId},
{'confirmed':confirmed},
{‘死亡’:死亡},
{'recovered':recovered},
];
}
}
列出国家=[];
可编辑列表;
show(){
印刷品(国家);
}
常量baseUrl=”https://covid-19-coronavirus-statistics.p.rapidapi.com/v1/stats";
类API{
静态未来getStats(){
返回http.get(baseUrl,标题:{
“x-rapidapi-host”:“新冠病毒-19-coronavirus-statistics.p.rapidapi.com”,
“x-rapidapi-key”:“8ca140a965mshe408a2e58737ba5p14b104jsn19a57561ec85”
});
}
}
当我导航到此页面时,会出现以下异常:
[ERROR:flutter/lib/ui/ui_dart_state.cc(157)] Unhandled Exception: type '_InternalLinkedHashMap<String, dynamic>' is not a subtype of type 'Iterable<dynamic>
[错误:flatter/lib/ui/ui\u dart\u state.cc(157)]未处理的异常:类型“\u InternalLinkedHashMap”不是类型“Iterable”的子类型
我是API新手,所以我不知道如何解决这个问题。任何帮助都将不胜感激。谢谢。json.decode(response.body)
返回一个映射类型的对象,该对象在dart中内部表示为\u InternalLinkedHashMap
。您可以从提供的API链接中看到此映射的结构。所需的数据位于该映射类型对象内的字段data
thencovid19Stats
下
API.getStats().then(
(response) => {
var response = json.decode(response.body),
countries = response['data']['covid19Stats'].map((model) => CovidData.fromJson(model)).toList(),
// print(json.decode(response.body)['data']['covid19Stats'][0])
}
);
您遇到的错误是由于调用了
.map
的方法签名,该签名属于地图类型对象上的Iterable
类(),该对象不是Iterable。我尝试了这个方法,并且我必须将国家类型更改为List,异常消失了。但当我将国家打印到控制台时,它会返回一个列表字段,其中包含“CovidData”是的实例,这就是您的代码所做的。您使用CovidData.fromJson
将response['data']['covid19Stats']
的每个元素转换为CovidData
对象,但是如何获取CovidData中的元素?您可以访问属性countries[0]
是CovidData
的一个实例<代码>国家[0]。城市将为您提供城市,国家[0]。国家将为您提供国家,依此类推。