javascript - 在 JSON API 中获取第一个数据
问题描述
我在使用 React 开发方面相对较新。我目前正在研究商品市场代码。我正在使用 fetch() 从 JSON API 获取和呈现数据。这是 JSON 的外观:
[
{
Symbol: "BIT:COM",
Ticker: "BIT",
Name: "Bitumen",
Country: "commodity",
Date: "2020-09-30T00:00:00",
State: "OPEN ",
Last: 2020,
Close: 2020,
CloseDate: "2020-09-30T00:00:00",
Group: "Industrial",
URL: "/commodity/bitumen",
Importance: 100,
DailyChange: -40,
DailyPercentualChange: -1.9417,
WeeklyChange: -284,
WeeklyPercentualChange: -12.3264,
MonthlyChange: -560,
MonthlyPercentualChange: -21.7054,
YearlyChange: -1140,
YearlyPercentualChange: -36.0759,
YTDChange: -1054,
YTDPercentualChange: -34.2876,
day_high: 2062,
day_low: 1930,
yesterday: 2060,
lastWeek: 2304,
lastMonth: 2580,
lastYear: 3160,
startYear: 3074,
decimals: 2,
unit: "CNY/T",
frequency: "Daily",
LastUpdate: "2020-10-05T07:33:00"
},
{
Symbol: "JBP:COM",
Ticker: "Steel",
Name: "Steel",
Country: "commodity",
Date: "2020-09-30T00:00:00",
State: "OPEN ",
Last: 3607,
Close: 3607,
CloseDate: "2020-09-30T00:00:00",
Group: "Industrial",
URL: "/commodity/steel",
Importance: 100,
DailyChange: -13,
DailyPercentualChange: -0.3591,
WeeklyChange: -15,
WeeklyPercentualChange: -0.4141,
MonthlyChange: -148,
MonthlyPercentualChange: -3.9414,
YearlyChange: -42,
YearlyPercentualChange: -1.151,
YTDChange: -135,
YTDPercentualChange: -3.6077,
day_high: 3628,
day_low: 3591,
yesterday: 3620,
lastWeek: 3622,
lastMonth: 3755,
lastYear: 3649,
startYear: 3742,
decimals: 2,
unit: "CNY/T",
frequency: "Daily",
LastUpdate: "2020-10-05T05:46:00"
}
]
如果您想查看完整的 JSON:https ://api.tradingeconomics.com/markets/commodities/?c=guest:guest&format=json
这就是我呈现数据的方式:
import React, {Component} from "react";
import List from './components/list'
class App extends Component{
state = {
data: []
}
componentDidMount() {
fetch('https://api.tradingeconomics.com/markets/commodities/?c=guest:guest&format=json')
.then(res => res.json())
.then((data) => {
this.setState({data: data})
})
.catch(console.log)
}
render() {
return (
<div className={'App'}>
<List data={this.state.data}/>
</div>
)
}
}
export default App;
以下是我获取数据的方式:
import React from "react";
const List = ({ data }) => {
return (
<div>
<h1>Commodities</h1>
{data.map((value) => (
<div>
<h5>Name: {value.Name}</h5>
<h5>Ticker: {value.Ticker}</h5>
<h5>High: {value.day_high}</h5>
<h5>Low: {value.day_low}</h5>
<h5>Unit: {value.unit}</h5>
<hr/>
</div>
))}
</div>
)
}
export default List;
我的问题是,如何获得第一个数据?假设我只想显示“BIT:COM”中的代码、名称和日期。现在用我的代码显示所有数据。提前谢谢你。
解决方案
你可以做这样的事情:
const List = ({ data }) => {
return (
<div>
<h1>Commodities</h1>
{data.map((value) => (
value.Name === "BIT:COM" ?
<div>
<h5>Name: {value.Name}</h5>
<h5>Ticker: {value.Ticker}</h5>
<h5>High: {value.day_high}</h5>
<h5>Low: {value.day_low}</h5>
<h5>Unit: {value.unit}</h5>
<hr/>
</div> : null
))}
</div>
)
}
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