Question

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"]}'),
        );
      },
    );
  }
}

Json

{“ SLVO”：{“统计信息” ：{“ week52change”：0.047256，“ week52high”：7.48，“ week52low”：6.23，“ marketcap”：null，“员工”：null ，“ day200MovingAvg”：6.88，“ day50MovingAvg”：7.13，“ float”：null，“ avg10Volume”：7454.8，“ avg30Volume”：7927.83，“ ttmEPS”：null，“ ttmDividendRate”：null，“ companyName”：“瑞士信贷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 ，“ exDividendDate”：null，“ peRatio”：null，“ beta”：-0.06347545711182472}，“ quote” ：{“ symbol”：“ SLVO”，“ companyName”：“瑞士信贷X-链接白银股票涵盖的电话ETN”，“ primaryExchange”：“ NASDAQ”，“ calculationPrice”：“ close”，“ open”：6.89，“ openTime”：1574346600589，“ cl ose“：6.88，” closeTime“：1574370000242，” high“：6.9，” low“：6.87，” latestPrice“：6.88，” latestSource“：” Close“，” latestTime“：” 11月21日，

已添加：＆types = 统计，引用和令牌

错误

I / flutter（28411）：例外：类型'（dynamic，dynamic，dynamic）=> void'不是'f'类型的'（String，dynamic）=> void'的子类型 I /颤振（28411）：71 I / flutter（28411）：异常：类型'（dynamic，dynamic，dynamic）=> void'不是'f'的类型'（String，dynamic）=> void'的子类型

Answer 1

我修改了url以包含统计信息并引用
您不能使用两个动态，它用于地图
而且您仍然需要动态字段名称
您可以添加令牌并以完整代码运行，演示图片如下所示
代码段

 Text ( '${photos[index].data["stats"]["dividendYield"] ?? ""}'),
 Text ( '${photos[index].data["stats"]["week52change"] ?? ""}'),
 Text ( '${photos[index].data["quote"]["companyName"] ?? ""}'),

演示

完整代码

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"]}'),
        );
      },
    );
  }
}

Flutter：例外：类型'（dynamic，dynamic，dynamic）=> void'不是'f'的类型'（String，dynamic）=> void'的子类型

1 个答案: