Flutter：从IEX JSON API检索股票统计信息和报价列表
IEX JSON API：
import 'package:http/http.dart' as http;
import 'dart:convert';
import '../models/stocks.dart';
Future<Map<String,dynamic>> getStocks() async {
// final String url =
'https://cloud.iexapis.com/stable/stock/market/batch?
symbols=aapl,fb&types=quote&token=Hidden';
// final client = new http.Client();
// final streamedRest = await client.send(
// http.Request('get', Uri.parse(url))
const url = 'https://cloud.iexapis.com/stable/stock/market/batch?s
ymbols=aapl,fb&types=quote&token=Hidden';
final response = await http.get(url);
final decodedResponse = json.decode(response.body).keys();
final data = Stocks.fromJson(decodedResponse);
//http.Response response = await http.get(Uri, headers: {"Accept":
"application/json"});
//print(jsonDecode(response.body).keys());
return jsonDecode(response.body).keys();
// return streamedRest.stream
// .transform(utf8.decoder)
// .transform(json.decoder)
// .expand((data) => (data as List<dynamic>))
// .map((data) => Stocks.fromJSON(data));
}
{“ AAPL”：{“ stats”：{“ week52change”：0.108189，“ week52high”：244.8，“ week52low”：142，“ marketcap”：1100781864400，“员工”：132000，“ day200MovingAvg”：196.46， “ day50MovingAvg”：220.62，“ float”：4512324403.94，“ avg10Volume”：23328121.8，“ avg30Volume”：26924247.43，“ ttmEPS”：11.8267，“ ttmDividendRate”：2.96，“ companyName”：“ Apple，Inc.”，“股票余额” ：4519180000，“ maxChangePercent”：240.1683，“ year5ChangePercent”：1.315，“ year2ChangePercent”：0.5505，“ year1ChangePercent”：0.108189，“ ytdChangePercent”：0.542427，“ month6ChangePercent”：0.186574，“ month3ChangePercent”：0.176601，“ month1ChangePercent”：0.1020 ，“ day30ChangePercent”：0.113509，“ day5ChangePercent”：0.030329，“ nextDividendDate”：null，“ dividendYield”：0.012152065029969619，“ nextEarningsDate”：“ 2019-10-30”，“ exDividendDate”：“ 2019-08-09”，“ peRatio“：20.75，” beta“：1.534551916699308}，” quote“：{” symbol“：” AAPL“，” companyName“：” Apple，Inc。“，” primaryExchange“：” NASDAQ“，” calculationPrice“：” tops “，” open“：null，” openTime“：null，” close“：null，” closeTime“：null，” high“：null，” low“：null，” latestPr ice”：245.395，“ latestSource”：“ IEX实时价格”，“ latestTime”：“ 12:37:57
日志：
在调试模式下为x86构建的Android SDK上启动lib \ main.dart ... 正在初始化gradle ... 解决依赖性... 正在运行Gradle任务'assembleDebug'... 构建build \ app \ outputs \ apk \ debug \ app-debug.apk。 I / OpenGLRenderer（4854）：初始化的EGL，版本1.4 D / OpenGLRenderer（4854）：交换行为1 D /（4854）：HostConnection :: get（）建立新的主机连接0xdc20bf00，tid 4881 D / EGL_emulation（4854）：eglCreateContext：0xe3d47760：maj 2 min 0 rcv 2 D / EGL_emulation（4854）：eglMakeCurrent：0xe3d47760：ver 2 0（tinfo 0xc6b24a30） D /（4854）：HostConnection :: get（）建立新的主机连接0xc6b386c0，TID 4874 D / EGL_emulation（4854）：eglCreateContext：0xdc27d780：maj 2 min 0 rcv 2 D / EGL_emulation（4854）：eglMakeCurrent：0xdc27d780：ver 2 0（tinfo 0xc6b24dc0） 正在将文件同步到针对x86构建的设备Android SDK ... I / Choreographer（4854）：跳过279帧！该应用程序可能在其主线程上做太多工作。 D / EGL_emulation（4854）：eglMakeCurrent：0xe3d47760：ver 2 0（tinfo 0xc6b24a30） I / OpenGLRenderer（4854）：戴维！持续时间= 6180ms;标志= 1，IntendedVsync = 596431275408，Vsync = 601081275222，OldestInputEvent = 9223372036854775807，NewestInputEvent = 0，HandleInputStart = 601083214976，AnimationStart = 601083253387，PerformTraversalsStart = 601083255696，DrawStart = 601096302305，SyncQueued = 601333900000s，StartStart = Draw535、694335335，SyncStart = Draw335 602308827762，FrameCompleted = 602612881859，DequeueBufferDuration = 66828000，QueueBufferDuration = 276000， D / EGL_emulation（4854）：eglMakeCurrent：0xdc27d780：ver 2 0（tinfo 0xc6b24dc0）
课程
import 'dart:convert';
Stocks stocksFromJson(String str) => Stocks.fromJson(json.decode(str));
String stocksToJson(Stocks data) => json.encode(data.toJson());
class Stocks {
String symbol;
String companyName;
String primaryExchange;
String calculationPrice;
int open;
int openTime;
double close;
int closeTime;
double high;
double low;
double latestPrice;
String latestSource;
String latestTime;
int latestUpdate;
int latestVolume;
dynamic iexRealtimePrice;
dynamic iexRealtimeSize;
dynamic iexLastUpdated;
double delayedPrice;
int delayedPriceTime;
double extendedPrice;
double extendedChange;
double extendedChangePercent;
int extendedPriceTime;
double previousClose;
int previousVolume;
int change;
double changePercent;
int volume;
dynamic iexMarketPercent;
dynamic iexVolume;
int avgTotalVolume;
dynamic iexBidPrice;
dynamic iexBidSize;
dynamic iexAskPrice;
dynamic iexAskSize;
int marketCap;
double peRatio;
double week52High;
int week52Low;
double ytdChange;
int lastTradeTime;
bool isUsMarketOpen;
Stocks({
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 Stocks.fromJson(Map<String, dynamic> json) => Stocks(
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> toJson() => {
"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,
};
}
没有错误产生，但是也没有结果。
预先感谢您的帮助！
1 个答案:
答案 0 :(得分：1)
看起来问题是if(floatvalue_A == 0.0){ warning: implicit conversion increases floating-point precision: 'float' to 'double'
QMessageBox::information(this, "empty","",QMessageBox::Ok);
}
，看起来您的API返回了JSON对象（地图）而不是JSON数组（列表）
我还弄清楚了另一个细节，“ AAPL”是JSON对象上的键，该值是另一个JSON对象，如果要将其值映射到.expand((data) => (data as List))，则可以使用扩展获取值“ AAPL”并将其传递给您的工厂Class
另一个重要的事情是，确保要尝试映射到fromJSON的键在传递的JSON对象中存在。
为了避免动态键（可能不会出现的键）出现问题，您可以使用Null感知运算符
使用dart中的可识别空值的运算符，您可以根据值是否为空来进行计算。它是较长表达式的简写。
一个建议，使事情变得简单一些，也许是不要使用Streams，您可以仅使用Future重构代码以实现异步操作
Class最后但并非最不重要的一点，我强烈建议您看一下：
- 我写了这段代码，但我无法理解我的错误
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