Flutter: Comment obtenir la méthode de carte imbriquée json

Nouveau sur Flutte / Dart. Quelle pourrait être la cause de mes problèmes de mappage?

Launching lib\main.dart on Android SDK built for x86 in debug mode...
Initializing gradle...
Resolving dependencies...
Running Gradle task 'assembleDebug'...
Built build\app\outputs\apk\debug\app-debug.apk.
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I/OpenGLRenderer( 5371): Initialized EGL, version 1.4
D/OpenGLRenderer( 5371): Swap behavior 1
D/        ( 5371): HostConnection::get() New Host Connection established 0xdd5d9200, tid 5399
D/EGL_emulation( 5371): eglCreateContext: 0xde80f4c0: maj 2 min 0 rcv 2
D/EGL_emulation( 5371): eglMakeCurrent: 0xde80f4c0: ver 2 0 (tinfo 0xde37faf0)
D/        ( 5371): HostConnection::get() New Host Connection established 0xc8bb7680, tid 5390
D/EGL_emulation( 5371): eglCreateContext: 0xde37cc00: maj 2 min 0 rcv 2
D/EGL_emulation( 5371): eglMakeCurrent: 0xde37cc00: ver 2 0 (tinfo 0xde37f810)
I/Choreographer( 5371): Skipped 411 frames!  The application may be doing too much work on its main thread.
D/EGL_emulation( 5371): eglMakeCurrent: 0xde80f4c0: ver 2 0 (tinfo 0xde37faf0)
Syncing files to device Android SDK built for x86...
I/OpenGLRenderer( 5371): Davey! duration=8078ms; Flags=1, IntendedVsync=1110681936778, Vsync=1117531936504, OldestInputEvent=9223372036854775807, NewestInputEvent=0, HandleInputStart=1117546732479, AnimationStart=1117546825482, PerformTraversalsStart=1117546831170, DrawStart=1117600733845, SyncQueued=1117602574377, SyncStart=1117645210311, IssueDrawCommandsStart=1117645436189, SwapBuffers=1118338480166, FrameCompleted=1118803458523, DequeueBufferDuration=29600000, QueueBufferDuration=176000, 
D/EGL_emulation( 5371): eglMakeCurrent: 0xde37cc00: ver 2 0 (tinfo 0xde37f810)
I/flutter ( 5371): Exception: type '_InternalLinkedHashMap<String, dynamic>' is not a subtype of type 'List<dynamic>'

Erreur

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=aapl,fb&types=quote&token=hidden');

  // 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 response) {
  List<Photo> Photos = new List<Photo>();
  List parsePhotos= json.decode(response.toString());
  for (int i = 0; i < parsePhotos.length; i++) {
    Photos.add(new Photo.fromJson(parsePhotos[i]));
  }
  return Photos;
}



class Photo {
  final String symbol;
  final String companyName;
  final String primaryExchange;
  final String calculationPrice;
  final int open;
  final int openTime;
  final double close;
  final int closeTime;
  final double high;
  final double low;
  final double latestPrice;
  final String latestSource;
  final String latestTime;
  final int latestUpdate;
  final int latestVolume;
  final dynamic iexRealtimePrice;
  final dynamic iexRealtimeSize;
  final dynamic iexLastUpdated;
  final double delayedPrice;
  final int delayedPriceTime;
  final double extendedPrice;
  final double extendedChange;
  final double extendedChangePercent;
  final int extendedPriceTime;
  final double previousClose;
  final int previousVolume;
  final int change;
  final double changePercent;
  final int volume;
  final dynamic iexMarketPercent;
  final dynamic iexVolume;
  final int avgTotalVolume;
  final dynamic iexBidPrice;
  final dynamic iexBidSize;
  final dynamic iexAskPrice;
  final dynamic iexAskSize;
  final int marketCap;
  final double peRatio;
  final double week52High;
  final int week52Low;
  final double ytdChange;
  final int lastTradeTime;
  final bool isUsMarketOpen;

  Photo({
    this.symbol,
    this.companyName,
    this.primaryExchange,
    this.calculationPrice,
    this.open,
    this.openTime,
    this.close,
    this.closeTime,
    this.high,
    this.low,
    this.latestPrice,
    this.latestSource,
    this.latestTime,
    this.latestUpdate,
    this.latestVolume,
    this.iexRealtimePrice,
    this.iexRealtimeSize,
    this.iexLastUpdated,
    this.delayedPrice,
    this.delayedPriceTime,
    this.extendedPrice,
    this.extendedChange,
    this.extendedChangePercent,
    this.extendedPriceTime,
    this.previousClose,
    this.previousVolume,
    this.change,
    this.changePercent,
    this.volume,
    this.iexMarketPercent,
    this.iexVolume,
    this.avgTotalVolume,
    this.iexBidPrice,
    this.iexBidSize,
    this.iexAskPrice,
    this.iexAskSize,
    this.marketCap,
    this.peRatio,
    this.week52High,
    this.week52Low,
    this.ytdChange,
    this.lastTradeTime,
    this.isUsMarketOpen,
  });

  factory Photo.fromJson(String str) => Photo.fromMap(json.decode(str));

  String toJson() => json.encode(toMap());

  factory Photo.fromMap(Map<String, dynamic> json) => Photo(
    symbol: json["symbol"],
    companyName: json["companyName"],
    primaryExchange: json["primaryExchange"],
    calculationPrice: json["calculationPrice"],
    open: json["open"],
    openTime: json["openTime"],
    close: json["close"].toDouble(),
    closeTime: json["closeTime"],
    high: json["high"].toDouble(),
    low: json["low"].toDouble(),
    latestPrice: json["latestPrice"].toDouble(),
    latestSource: json["latestSource"],
    latestTime: json["latestTime"],
    latestUpdate: json["latestUpdate"],
    latestVolume: json["latestVolume"],
    iexRealtimePrice: json["iexRealtimePrice"],
    iexRealtimeSize: json["iexRealtimeSize"],
    iexLastUpdated: json["iexLastUpdated"],
    delayedPrice: json["delayedPrice"].toDouble(),
    delayedPriceTime: json["delayedPriceTime"],
    extendedPrice: json["extendedPrice"].toDouble(),
    extendedChange: json["extendedChange"].toDouble(),
    extendedChangePercent: json["extendedChangePercent"].toDouble(),
    extendedPriceTime: json["extendedPriceTime"],
    previousClose: json["previousClose"].toDouble(),
    previousVolume: json["previousVolume"],
    change: json["change"],
    changePercent: json["changePercent"].toDouble(),
    volume: json["volume"],
    iexMarketPercent: json["iexMarketPercent"],
    iexVolume: json["iexVolume"],
    avgTotalVolume: json["avgTotalVolume"],
    iexBidPrice: json["iexBidPrice"],
    iexBidSize: json["iexBidSize"],
    iexAskPrice: json["iexAskPrice"],
    iexAskSize: json["iexAskSize"],
    marketCap: json["marketCap"],
    peRatio: json["peRatio"].toDouble(),
    week52High: json["week52High"].toDouble(),
    week52Low: json["week52Low"],
    ytdChange: json["ytdChange"].toDouble(),
    lastTradeTime: json["lastTradeTime"],
    isUsMarketOpen: json["isUSMarketOpen"],
  );

  Map<String, dynamic> toMap() => {
    "symbol": symbol,
    "companyName": companyName,
    "primaryExchange": primaryExchange,
    "calculationPrice": calculationPrice,
    "open": open,
    "openTime": openTime,
    "close": close,
    "closeTime": closeTime,
    "high": high,
    "low": low,
    "latestPrice": latestPrice,
    "latestSource": latestSource,
    "latestTime": latestTime,
    "latestUpdate": latestUpdate,
    "latestVolume": latestVolume,
    "iexRealtimePrice": iexRealtimePrice,
    "iexRealtimeSize": iexRealtimeSize,
    "iexLastUpdated": iexLastUpdated,
    "delayedPrice": delayedPrice,
    "delayedPriceTime": delayedPriceTime,
    "extendedPrice": extendedPrice,
    "extendedChange": extendedChange,
    "extendedChangePercent": extendedChangePercent,
    "extendedPriceTime": extendedPriceTime,
    "previousClose": previousClose,
    "previousVolume": previousVolume,
    "change": change,
    "changePercent": changePercent,
    "volume": volume,
    "iexMarketPercent": iexMarketPercent,
    "iexVolume": iexVolume,
    "avgTotalVolume": avgTotalVolume,
    "iexBidPrice": iexBidPrice,
    "iexBidSize": iexBidSize,
    "iexAskPrice": iexAskPrice,
    "iexAskSize": iexAskSize,
    "marketCap": marketCap,
    "peRatio": peRatio,
    "week52High": week52High,
    "week52Low": week52Low,
    "ytdChange": ytdChange,
    "lastTradeTime": lastTradeTime,
    "isUSMarketOpen": isUsMarketOpen,
  };
}


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;
//  final parsePhotos = json.decode(response.body).cast<Map<String, dynamic>>();
  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 Image.network(photos[index].companyName);
      },
    );
  }
}

p >

Résultats Json:

{"AAPL": {"stats": {"week52change": 0,232986, "week52high": 255,93, "week52low": 142, "marketcap": 1136677331400, "employés": 137000, "day200MovingAvg": 199,29, "day50MovingAvg": 225.28, "float": 4436680630.59, "avg10Volume": 26482506.4, "avg30Volume": 26817874.5, "ttmEPS": 11.9342, "ttmDividendRate": 3, "companyName", "Apple, Inc. : 4443270000, "maxChangePercent": 252.2871, "year5ChangePercent": 1.3384, "year2ChangePercent": 0.5329, "year1ChangePercent": 0.1512, "ytdChangePercent": 0.6199, "month6ChangePercent": 0.2152, "month6ChangePercent": 0.2152, "mois , "day30ChangePercent": 0.1696, "day5ChangePercent": 0.0272, "nextDividendDate": "2019-11-07", "dividendYield": 0.011726995543741695, "nextEarningsDate": "2020-02-04", "exDividendDate": "2019- 11-07 "," peRatio ": 21.44," beta ": 1.534927573962706}," quote ": {" symbol ":" AAPL "," companyName ":" Apple, Inc. "," PrimaryExchange ":" NASDAQ ", "calculPrice": "close", "open": 249,5, "openTime": 1572615000544, "close": 255.82, "closeTime": 1572638400572, "high": 255.93, "low ": 249.16," latestPrice ": 255.82," latestSource ":" Close "," latestTime ":" 1 novembre 2019 "," latestUpdate ": 1572638400572," latestVolume ": 38139225," iexRealtimePrice ": null, p >

Capture d'écran Json

[

Trace de pile

{"AAPL": {"stats": {"week52change": 0,232986, "week52high": 255,93, "week52low": 142, "marketcap": 1136677331400, "employés": 137000, "day200MovingAvg": 199,29, "day50MovingAvg": 225.28, "float": 4436680630.59, "avg10Volume": 26482506.4, "avg30Volume": 26817874.5, "ttmEPS": 11.9342, "ttmDividendRate": 3, "companyName", "Apple, Inc. : 4443270000, "maxChangePercent": 252.2871, "year5ChangePercent": 1.3384, "year2ChangePercent": 0.5329, "year1ChangePercent": 0.1512, "ytdChangePercent": 0.6199, "month6ChangePercent": 0.2152, "month6ChangePercent": 0.2152, "mois , "day30ChangePercent": 0.1696, "day5ChangePercent": 0.0272, "nextDividendDate": "2019-11-07", "dividendYield": 0.011726995543741695, "nextEarningsDate": "2020-02-04", "exDividendDate": "2019- 11-07 "," peRatio ": 21.44," beta ": 1.534927573962706}," quote ": {" symbol ":" AAPL "," companyName ":" Apple, Inc. "," PrimaryExchange ":" NASDAQ ", "calculPrice": "close", "open": 249,5, "openTime": 1572615000544, "close": 255.82, "closeTime": 1572638400572, "high": 255.93, "low ": 249.16," latestPrice ": 255.82," latestSource ":" Close "," latestTime ":" 1 novembre 2019 "," latestUpdate ": 1572638400572," latestVolume ": 38139225," iexRealtimePrice ": null, p >

Screenshot

Attendu: Exemple: https://flutter.dev/docs/cookbook/networking/background-parsing