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如何将多个json对象添加/映射到dart对象
import 'dart:async';
import 'dart:convert';
import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';
import 'package:http/http.dart' as http;
Future<List<Photo>> fetchPhotos(http.Client client) async {
final response =
await client.get('https://cloud.iexapis.com/stable/stock/market/batch?symbols=SLVO,MONY&types=stats&token=');
/*String response = '''
{"AAPL":
{"stats":{"week52change":0.232986,"week52high":255.93,"week52low":142,"marketcap":1136677331400,"employees":137000,"day200MovingAvg":199.29,"day50MovingAvg":225.28,"float":4436680630.59,"avg10Volume":26482506.4,"avg30Volume":26817874.5,"ttmEPS":11.9342,"ttmDividendRate":3,"companyName":"Apple, Inc."
}
},
"FB":
{"stats":{"week52change":0.1,"week52high":255.93,"week52low":142,"marketcap":1136677331400,"employees":137000,"day200MovingAvg":199.29,"day50MovingAvg":225.28,"float":4436680630.59,"avg10Volume":26482506.4,"avg30Volume":26817874.5,"ttmEPS":11.9342,"ttmDividendRate":3,"companyName":"Apple, Inc."
}
}
}
''';*/
// Use the compute function to run parsePhotos in a separate isolate.
return compute(parsePhotos, response.body);
}
// A function that converts a response body into a List<Photo>.
List<Photo> parsePhotos(String responseBody) {
//final parsed = json.decode(responseBody).cast<Map<String,dynamic>>();
//return parsed.map<Photo>((json) => Photo.fromJson(json)).toList();
dynamic Obj = json.decode(responseBody);
print(Obj.length);
List<Photo> photoList = [];
Obj.forEach((k, v,z) => photoList.add(Photo(k,v,z)));
return photoList;
}
class Photo {
String symbol;
String companyName;
dynamic stats;
//dynamic stats;
Photo(this.symbol ,this.stats,this.companyName);
}
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
final appTitle = 'Isolate Demo';
return MaterialApp(
title: appTitle,
home: MyHomePage(title: appTitle),
);
}
}
class MyHomePage extends StatelessWidget {
final String title;
MyHomePage({Key key, this.title}) : super(key: key);
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text(title),
),
body: FutureBuilder<List<Photo>>(
future: fetchPhotos(http.Client()),
builder: (context, snapshot) {
if (snapshot.hasError) print(snapshot.error);
return snapshot.hasData
? PhotosList(photos: snapshot.data)
: Center(child: CircularProgressIndicator());
},
),
);
}
}
class PhotosList extends StatelessWidget {
final List<Photo> photos;
PhotosList({Key key, this.photos}) : super(key: key);
@override
Widget build(BuildContext context) {
return GridView.builder(
gridDelegate: SliverGridDelegateWithFixedCrossAxisCount(
crossAxisCount: 2,
),
itemCount: photos.length,
itemBuilder: (context, index) {
return ListTile(
leading: Icon(Icons.album),
title: Column( children: [
Text(photos[index].symbol),
Text(photos[index].companyName),
],
),
subtitle: Column(
children: [
// Text( ' ${photos[index].stats["stats"]["dividendYield"]["companyName"]}'),
// Text( ' ${photos[index].data["quote"]["iexRealtimePrice"]}' ' ${photos[index].stats["stats"]["dividendYield"]["companyName"]}'),
// Text( ' ${photos[index].data["quote"]["iexRealtimePrice"]}'),
Text ( '${photos[index].stats["dividendYield"] ?? ""}'),
],
),
//title: Text(photos[index].symbol),
//subtitle: Text( ' ${photos[index].stats["stats"]["dividendYield"]["companyName"]}'),
//subtitle: Text( ' ${photos[index].data["quote"]["iexRealtimePrice"]}' ' ${photos[index].stats["stats"]["dividendYield"]["companyName"]}'),
// subtitle: Text( ' ${photos[index].data["quote"]["iexRealtimePrice"]}'),
// subtitle: Text ( ' ${photos[index].stats["stats"]["dividendYield"]}'),
);
},
);
}
}
{"SLVO":{"stats":{"week52change":0.047256,"week52high":7.48,"week52low":6.23,"marketcap":null,"employees":null,"day200MovingAvg":6.88,"day50MovingAvg":7.13,"float":null,"avg10Volume":7454.8,"avg30Volume":7927.83,"ttmEPS":null,"ttmDividendRate":null,"companyName":"Credit Suisse X-Links Silver Shares Covered Call ETN","sharesOutstanding":0,"maxChangePercent":58.7391,"year5ChangePercent":-0.4128,"year2ChangePercent":-0.1369,"year1ChangePercent":0.047256,"ytdChangePercent":-0.005789,"month6ChangePercent":0.074445,"month3ChangePercent":-0.035112,"month1ChangePercent":-0.025532,"day30ChangePercent":-0.035112,"day5ChangePercent":-0.007225,"nextDividendDate":null,"dividendYield":null,"nextEarningsDate":null,"exDividendDate":null,"peRatio":null,"beta":-0.06347545711182472},"quote":{"symbol":"SLVO","companyName":"Credit Suisse X-Links Silver Shares Covered Call ETN","primaryExchange":"NASDAQ","calculationPrice":"close","open":6.89,"openTime":1574346600589,"close":6.88,"closeTime":1574370000242,"high":6.9,"low":6.87,"latestPrice":6.88,"latestSource":"Close","latestTime":"November 21,
已添加:
&types = 统计信息,引用和 token
错误
I/flutter (28411): Exception: type '(dynamic, dynamic, dynamic) => void' is not a subtype of type '(String, dynamic) => void' of 'f' I/flutter (28411): 71 I/flutter (28411): Exception: type '(dynamic, dynamic, dynamic) => void' is not a subtype of type '(String, dynamic) => void' of 'f'
最佳答案
我已经修改了网址以包含统计信息和报价
您不能使用两个动态,其用于 map
而且您仍然需要动态字段名称
您可以添加 token 并以完整代码运行,演示图片如下
程式码片段
Text ( '${photos[index].data["stats"]["dividendYield"] ?? ""}'),
Text ( '${photos[index].data["stats"]["week52change"] ?? ""}'),
Text ( '${photos[index].data["quote"]["companyName"] ?? ""}'),
import 'dart:async';
import 'dart:convert';
import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';
import 'package:http/http.dart' as http;
Future<List<Photo>> fetchPhotos(http.Client client) async {
final response =
await client.get('https://cloud.iexapis.com/stable/stock/market/batch?symbols=SLVO,MONY&types=stats,quote&token=');
// Use the compute function to run parsePhotos in a separate isolate.
return compute(parsePhotos, response.body);
}
// A function that converts a response body into a List<Photo>.
List<Photo> parsePhotos(String responseBody) {
//final parsed = json.decode(responseBody).cast<Map<String,dynamic>>();
//return parsed.map<Photo>((json) => Photo.fromJson(json)).toList();
dynamic Obj = json.decode(responseBody);
print(responseBody);
print(Obj.length);
List<Photo> photoList = [];
Obj.forEach((k, v) => photoList.add(Photo(k,v)));
return photoList;
}
class Photo {
String symbol;
//String companyName;
dynamic data;
//dynamic quote;
Photo(this.symbol ,this.data);
}
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
final appTitle = 'Isolate Demo';
return MaterialApp(
title: appTitle,
home: MyHomePage(title: appTitle),
);
}
}
class MyHomePage extends StatelessWidget {
final String title;
MyHomePage({Key key, this.title}) : super(key: key);
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text(title),
),
body: FutureBuilder<List<Photo>>(
future: fetchPhotos(http.Client()),
builder: (context, snapshot) {
if (snapshot.hasError) print(snapshot.error);
return snapshot.hasData
? PhotosList(photos: snapshot.data)
: Center(child: CircularProgressIndicator());
},
),
);
}
}
class PhotosList extends StatelessWidget {
final List<Photo> photos;
PhotosList({Key key, this.photos}) : super(key: key);
@override
Widget build(BuildContext context) {
return GridView.builder(
gridDelegate: SliverGridDelegateWithFixedCrossAxisCount(
crossAxisCount: 2,
),
itemCount: photos.length,
itemBuilder: (context, index) {
return ListTile(
leading: Icon(Icons.album),
title: Column( children: [
Text(photos[index].symbol),
//Text(photos[index].companyName),
],
),
subtitle: Column(
children: [
// Text( ' ${photos[index].stats["stats"]["dividendYield"]["companyName"]}'),
// Text( ' ${photos[index].data["quote"]["iexRealtimePrice"]}' ' ${photos[index].stats["stats"]["dividendYield"]["companyName"]}'),
// Text( ' ${photos[index].data["quote"]["iexRealtimePrice"]}'),
Text ( '${photos[index].data["stats"]["dividendYield"] ?? ""}'),
Text ( '${photos[index].data["stats"]["week52change"] ?? ""}'),
Text ( '${photos[index].data["quote"]["companyName"] ?? ""}'),
],
),
//title: Text(photos[index].symbol),
//subtitle: Text( ' ${photos[index].stats["stats"]["dividendYield"]["companyName"]}'),
//subtitle: Text( ' ${photos[index].data["quote"]["iexRealtimePrice"]}' ' ${photos[index].stats["stats"]["dividendYield"]["companyName"]}'),
// subtitle: Text( ' ${photos[index].data["quote"]["iexRealtimePrice"]}'),
// subtitle: Text ( ' ${photos[index].stats["stats"]["dividendYield"]}'),
);
},
);
}
}
关于flutter - Flutter:异常(exception): '(dynamic, dynamic, dynamic) => void'类型不是 '(String, dynamic) => void'的 'f'类型的子类型,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/59028843/
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