在下面的异步函数中,我调用stationData只是为了确认是否要将对象数组传递给bartData(这只是一个空数组)。附件是我正在接收的对象数组的响应。但是,当尝试使用this.state.bartData(以确认它确实具有对象数组)时,我的return函数将bartData作为未定义返回。有任何想法吗?
import React from 'react';
const bartKey = process.env.REACT_API_BART_API_KEY;
class StationBaseRoutes extends React.Component{
constructor(props){
super(props);
this.state = {
isLoading: true,
station: [],
stationAbbv: 'ALL',
destination: '',
bartData: []
}
}
componentDidMount(){
this.getAllStationRoutes();
}
async getAllStationRoutes(){
try{
setInterval(async () => {
const response = await fetch(`http://api.bart.gov/api/etd.aspx?cmd=etd&orig=${this.state.stationAbbv}&key=${bartKey}&json=y`);
const jsonResponse = await response.json();
const apiData = jsonResponse.root;
const stationData = apiData.station;
console.log(stationData);
this.setState(({
isLoading: false,
bartData: stationData
}), () => {
console.log(`Callback: ${this.state.bartData}`)
})
}, 20000)
} catch(error){
console.log(error);
}
}
getRoutes = () => {
console.log(`bartData: ${this.bartData}`)
}
render(){
const {station, destination} = this.state;
return(
<div>
<h2>Calling get routes: {this.getRoutes()}</h2>
<h2>Origin: {station}</h2>
<h3>Destination: {destination}</h3>
</div>
)
}
}
export default StationBaseRoutes;
回应:https://imgur.com/gallery/Luk9MCX
最佳答案
我无法使Bart API在codeandbox中工作,因此我不得不模拟该API ...但是,数据的结构仍然相同。
关于这一点,该API可以按预期工作,您只需要在map
数组中的objects
上进行this.state.bartData
并解构要显示的属性。
工作示例:https://codesandbox.io/s/031pn7w680
import map from "lodash/map";
import React, { Component, Fragment } from "react";
import { fakeAPI } from "../../api/fakeAPI";
class StationBaseRoutes extends Component {
constructor(props) {
super(props);
this.state = {
isLoading: true,
station: [],
stationAbbv: "ALL",
destination: "",
bartData: []
};
this.getAllStationRoutes = this.getAllStationRoutes.bind(this);
}
componentDidMount() {
this.getAllStationRoutes();
}
async getAllStationRoutes() {
try {
const res = await fakeAPI.get();
const apiData = res.data.root;
const stationData = apiData.station;
this.setState({
isLoading: false,
bartData: stationData
});
} catch (error) {
console.log(error);
}
}
render() {
const { bartData, isLoading } = this.state;
return (
<div className="app-container">
{isLoading ? (
<p className="t-a-c">Loading...</p>
) : (
<Fragment>
<h1 className="t-a-c">Bart Stations</h1>
{map(bartData, ({ name, etd }) => (
<div className="jumbotron station" key={name}>
<h1>Origin: {name}</h1>
{map(etd, ({ destination }) => (
<li key={destination}>Destination: {destination}</li>
))}
</div>
))}
<pre className="preview">
<code>{JSON.stringify(bartData, null, 4)}</code>
</pre>
</Fragment>
)}
</div>
);
}
}
export default StationBaseRoutes;