Flutter 转换后的JSON在listView中不显示任何内容
我正在使用Cat API,并试图在列表中显示数据。 我试图转换反应Flutter 转换后的JSON在listView中不显示任何内容,flutter,dart,Flutter,Dart,我正在使用Cat API,并试图在列表中显示数据。 我试图转换反应 Future<List<CatData>> fetchCats(http.Client client) async { final response = await client.get('https://api.thecatapi.com/v1/breeds/'); return compute(parseCat, response.body); } List<CatData> p
Future<List<CatData>> fetchCats(http.Client client) async {
final response = await client.get('https://api.thecatapi.com/v1/breeds/');
return compute(parseCat, response.body);
}
List<CatData> parseCat(responseBody) {
final parsed = jsonDecode(responseBody) as Map<String, dynamic>;
return parsed[""].map<CatData>((json) => CatData.fromJson(json)).toList();
}
Future fetchCats(http.Client)异步{
最终响应=等待客户端。获取('https://api.thecatapi.com/v1/breeds/');
返回compute(parseCat,response.body);
}
列表parseCat(响应库){
最终解析=jsonDecode(responseBody)作为映射;
返回已解析的[“”].map((json)=>CatData.fromJson(json)).toList();
}
但列表并没有显示任何内容。由于
json
文件以[]开头,因此return parsed[“”]
中很可能出现错误。如何修复此问题?Cat API的响应是对象列表。因此,您可以将解析后的响应转换为列表,并对其进行转换。另外,解析的[“”]
也无效
List parseCat(responseBody){
最终解析=jsonDecode(responseBody)作为列表;
返回parsed.map((json)=>CatData.fromJson(json)).toList();
}
您可以复制粘贴运行下面的完整代码您可以使用
catDataFromJson
,有关详细信息,请参阅完整代码您可以在
parseCat
中直接返回catDataFromJson(responseBody)代码>
代码片段
List<CatData> catDataFromJson(String str) =>
List<CatData>.from(json.decode(str).map((x) => CatData.fromJson(x)));
List<CatData> parseCat(String responseBody) {
return catDataFromJson(responseBody);
}
List catDataFromJson(String str)=>
List.from(json.decode(str.map)(x)=>CatData.fromJson(x));
列表parseCat(字符串响应库){
返回catDataFromJson(responseBody);
}
工作演示
完整代码
import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';
import 'package:http/http.dart' as http;
import 'dart:convert';
List<CatData> catDataFromJson(String str) =>
List<CatData>.from(json.decode(str).map((x) => CatData.fromJson(x)));
String catDataToJson(List<CatData> data) =>
json.encode(List<dynamic>.from(data.map((x) => x.toJson())));
class CatData {
CatData({
this.weight,
this.id,
this.name,
this.cfaUrl,
this.vetstreetUrl,
this.vcahospitalsUrl,
this.temperament,
this.origin,
this.countryCodes,
this.countryCode,
this.description,
this.lifeSpan,
this.indoor,
this.lap,
this.altNames,
this.adaptability,
this.affectionLevel,
this.childFriendly,
this.dogFriendly,
this.energyLevel,
this.grooming,
this.healthIssues,
this.intelligence,
this.sheddingLevel,
this.socialNeeds,
this.strangerFriendly,
this.vocalisation,
this.experimental,
this.hairless,
this.natural,
this.rare,
this.rex,
this.suppressedTail,
this.shortLegs,
this.wikipediaUrl,
this.hypoallergenic,
this.catFriendly,
this.bidability,
});
Weight weight;
String id;
String name;
String cfaUrl;
String vetstreetUrl;
String vcahospitalsUrl;
String temperament;
String origin;
String countryCodes;
String countryCode;
String description;
String lifeSpan;
int indoor;
int lap;
String altNames;
int adaptability;
int affectionLevel;
int childFriendly;
int dogFriendly;
int energyLevel;
int grooming;
int healthIssues;
int intelligence;
int sheddingLevel;
int socialNeeds;
int strangerFriendly;
int vocalisation;
int experimental;
int hairless;
int natural;
int rare;
int rex;
int suppressedTail;
int shortLegs;
String wikipediaUrl;
int hypoallergenic;
int catFriendly;
int bidability;
factory CatData.fromJson(Map<String, dynamic> json) => CatData(
weight: Weight.fromJson(json["weight"]),
id: json["id"],
name: json["name"],
cfaUrl: json["cfa_url"] == null ? null : json["cfa_url"],
vetstreetUrl:
json["vetstreet_url"] == null ? null : json["vetstreet_url"],
vcahospitalsUrl:
json["vcahospitals_url"] == null ? null : json["vcahospitals_url"],
temperament: json["temperament"],
origin: json["origin"],
countryCodes: json["country_codes"],
countryCode: json["country_code"],
description: json["description"],
lifeSpan: json["life_span"],
indoor: json["indoor"],
lap: json["lap"] == null ? null : json["lap"],
altNames: json["alt_names"] == null ? null : json["alt_names"],
adaptability: json["adaptability"],
affectionLevel: json["affection_level"],
childFriendly: json["child_friendly"],
dogFriendly: json["dog_friendly"],
energyLevel: json["energy_level"],
grooming: json["grooming"],
healthIssues: json["health_issues"],
intelligence: json["intelligence"],
sheddingLevel: json["shedding_level"],
socialNeeds: json["social_needs"],
strangerFriendly: json["stranger_friendly"],
vocalisation: json["vocalisation"],
experimental: json["experimental"],
hairless: json["hairless"],
natural: json["natural"],
rare: json["rare"],
rex: json["rex"],
suppressedTail: json["suppressed_tail"],
shortLegs: json["short_legs"],
wikipediaUrl:
json["wikipedia_url"] == null ? null : json["wikipedia_url"],
hypoallergenic: json["hypoallergenic"],
catFriendly: json["cat_friendly"] == null ? null : json["cat_friendly"],
bidability: json["bidability"] == null ? null : json["bidability"],
);
Map<String, dynamic> toJson() => {
"weight": weight.toJson(),
"id": id,
"name": name,
"cfa_url": cfaUrl == null ? null : cfaUrl,
"vetstreet_url": vetstreetUrl == null ? null : vetstreetUrl,
"vcahospitals_url": vcahospitalsUrl == null ? null : vcahospitalsUrl,
"temperament": temperament,
"origin": origin,
"country_codes": countryCodes,
"country_code": countryCode,
"description": description,
"life_span": lifeSpan,
"indoor": indoor,
"lap": lap == null ? null : lap,
"alt_names": altNames == null ? null : altNames,
"adaptability": adaptability,
"affection_level": affectionLevel,
"child_friendly": childFriendly,
"dog_friendly": dogFriendly,
"energy_level": energyLevel,
"grooming": grooming,
"health_issues": healthIssues,
"intelligence": intelligence,
"shedding_level": sheddingLevel,
"social_needs": socialNeeds,
"stranger_friendly": strangerFriendly,
"vocalisation": vocalisation,
"experimental": experimental,
"hairless": hairless,
"natural": natural,
"rare": rare,
"rex": rex,
"suppressed_tail": suppressedTail,
"short_legs": shortLegs,
"wikipedia_url": wikipediaUrl == null ? null : wikipediaUrl,
"hypoallergenic": hypoallergenic,
"cat_friendly": catFriendly == null ? null : catFriendly,
"bidability": bidability == null ? null : bidability,
};
}
class Weight {
Weight({
this.imperial,
this.metric,
});
String imperial;
String metric;
factory Weight.fromJson(Map<String, dynamic> json) => Weight(
imperial: json["imperial"],
metric: json["metric"],
);
Map<String, dynamic> toJson() => {
"imperial": imperial,
"metric": metric,
};
}
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();
}
List<CatData> parseCat(String responseBody) {
return catDataFromJson(responseBody);
}
class _MyHomePageState extends State<MyHomePage> {
Future<List<CatData>> _future;
Future<List<CatData>> fetchCats(http.Client client) async {
final response = await client.get('https://api.thecatapi.com/v1/breeds/');
return compute(parseCat, response.body);
}
@override
void initState() {
_future = fetchCats(http.Client());
super.initState();
}
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text(widget.title),
),
body: FutureBuilder(
future: _future,
builder: (context, AsyncSnapshot<List<CatData>> 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].name.toString()),
Spacer(),
Text(snapshot.data[index].id),
],
),
));
});
}
}
}));
}
}
导入“包:flift/foundation.dart”;
进口“包装:颤振/材料.省道”;
将“package:http/http.dart”导入为http;
导入“dart:convert”;
列表catDataFromJson(字符串str)=>
List.from(json.decode(str.map)(x)=>CatData.fromJson(x));
字符串catDataToJson(列表数据)=>
encode(List.from(data.map((x)=>x.toJson());
类别CatData{
CatData({
这个重量,
这个身份证,
这个名字,
这个.cfaUrl,
这个.vetstreetUrl,
此.vcahospitalURL,
这个气质,,
这个,起源,,
这是国家代码,
这个国家代码,
这个.说明,,
这个,寿命,
这是室内的,
这一圈,
这是我的名字,
这就是适应性,
这个层次,,
这是对孩子友好的,
这只狗很友好,
这是energyLevel,
这个,打扮,
这是一个健康问题,
这就是我的智慧,
这是谢丁格勒维尔,
这是社会需要,,
这个,奇怪的友好,
这个,发声,
这是实验性的,
这个,无毛,
这是自然的,
这是罕见的,
这是雷克斯先生,
这个.抑制的尾巴,
这个,短腿,
这个.wikipediaUrl,
这是低致敏性,
这是友好的,
这就是可投标性,
});
重量;
字符串id;
字符串名;
字符串cfaUrl;
字符串vetstreetUrl;
字符串vcahospitalsUrl;
弦乐气质;
弦源;
字符串国家代码;
字符串国家代码;
字符串描述;
线寿命;
室内;
内圈;
字符串名称;
内在适应性;
智力水平;
int儿童友好型;
对狗友好;
国际能源水平;
整容;
国际卫生问题;
智力;
内舍丁格勒维尔;
国际社会需要;
奇怪的友好;
内发声;
int实验;
无毛;
int-natural;
int罕见;
int-rex;
int-suppressedTail;
短腿;
字符串wikipediaUrl;
低过敏性;
友好的;
不可投标性;
工厂CatData.fromJson(映射json)=>CatData(
weight:weight.fromJson(json[“weight”]),
id:json[“id”],
名称:json[“名称”],
cfaUrl:json[“cfa_url”]==null?null:json[“cfa_url”],
vetstreetUrl:
json[“vetstreet_url”]==null?null:json[“vetstreet_url”],
vCAhospitalURL:
json[“vcahospitals_url”]==null?null:json[“vcahospitals_url”],
气质:json[“气质”],
来源:json[“来源”],
countryCodes:json[“国家代码”],
countryCode:json[“国家代码”],
description:json[“description”],
寿命:json[“寿命”],
室内:json[“室内”],
lap:json[“lap”]==null?null:json[“lap”],
altNames:json[“alt_names”]==null?null:json[“alt_names”],
适应性:json[“适应性”],
情感等级:json[“情感等级”],
儿童友好型:json[“儿童友好型”],
dogFriendly:json[“dog_-friendly”],
energyLevel:json[“能量级别”],
修饰:json[“修饰”],
healthIssues:json[“健康问题”],
智能:json[“智能”],
sheddingLevel:json[“脱落水平”],
社交需求:json[“社交需求”],
陌生友好:json[“陌生友好”],
发声:json[“发声”],
实验性:json[“实验性”],
无毛:json[“无毛”],
natural:json[“natural”],
稀有:json[“稀有”],
rex:json[“rex”],
suppressedTail:json[“suppressed_tail”],
短腿:json[“短腿”],
维基百科网址:
json[“维基百科url”]==null?null:json[“维基百科url”],
低致敏性:json[“低致敏性”],
catFriendly:json[“cat_friendly”]==null?null:json[“cat_friendly”],
可投标性:json[“可投标性”]==null?null:json[“可投标性”],
);
映射到JSON()=>{
“weight”:weight.toJson(),
“id”:id,
“姓名”:姓名,
“cfa_url”:cfaUrl==null?null:cfaUrl,
“vetstreet_url”:vetstreetUrl==null?null:vetstreetUrl,
“vcahospitals_url”:vcahospitalsUrl==null?null:vcahospitalsUrl,
“气质”:气质,
“起源”:起源,
“国家代码”:国家代码,
“国家代码”:国家代码,
“描述”:描述,
“寿命”:寿命,
“室内”:室内,
“lap”:lap==null?null:lap,
“alt_names”:altNames==null?null:altNames,
"适应性":适应性,,
“情感水平”:情感水平,
“儿童友好型”