我正在按照教程制作一个新闻应用程序,我正在从newapi获取数据,我的代码与教程中的代码相同,但是在我更新状态(this.state.articles)后,我的组件没有改变。我使用了setState函数,我尝试在控制台记录状态,状态在更新后看起来很好,render方法运行了,但是没有改变任何内容,可能出了什么问题
我的代码/组件
import React, { Component } from 'react' import NewsItem from './NewsItem' export default class News extends Component { articles = [ { "source": { "id": "espn-cric-info", "name": "ESPN Cric Info" }, "author": null, "title": "PCB hands Umar Akmal three-year ban from all cricket | ESPNcricinfo.com", "description": "Penalty after the batsman pleaded guilty to not reporting corrupt approaches | ESPNcricinfo.com", "url": "http://www.espncricinfo.com/story/_/id/29103103/pcb-hands-umar-akmal-three-year-ban-all-cricket", "urlToImage": "https://a4.espncdn.com/combiner/i?img=%2Fi%2Fcricket%2Fcricinfo%2F1099495_800x450.jpg", "publishedAt": "2020-04-27T11:41:47Z", "content": "Umar Akmal's troubled cricket career has hit its biggest roadblock yet, with the PCB handing him a ban from all representative cricket for three years after he pleaded guilty of failing to report det… [+1506 chars]" }, { "source": { "id": "espn-cric-info", "name": "ESPN Cric Info" }, "author": null, "title": "What we learned from watching the 1992 World Cup final in full again | ESPNcricinfo.com", "description": "Wides, lbw calls, swing - plenty of things were different in white-ball cricket back then | ESPNcricinfo.com", "url": "http://www.espncricinfo.com/story/_/id/28970907/learned-watching-1992-world-cup-final-full-again", "urlToImage": "https://a4.espncdn.com/combiner/i?img=%2Fi%2Fcricket%2Fcricinfo%2F1219926_1296x729.jpg", "publishedAt": "2020-03-30T15:26:05Z", "content": "Last week, we at ESPNcricinfo did something we have been thinking of doing for eight years now: pretend-live ball-by-ball commentary for a classic cricket match. We knew the result, yes, but we tried… [+6823 chars]" } ] constructor() { super(); this.state = { articles: this.articles, loading: false } } async componentDidMount() { const URL = "https://newsapi.org/v2/top-headlines?country=us&category=business&apiKey=" let data = await fetch(URL); let parsedData = await data.json() this.setState({ articles: parsedData.articles }) console.log(this.state.articles) } render() { console.log("render") return ( <div> <div className="container"> <h2 className='my-4 mx-4'> NewsMonkey - Top Headlines </h2> <div className="row"> {this.articles.map((elem) => { return <div className="col-md-4" key={elem.url}> <NewsItem title={elem.title?elem.title.slice(42):""} desc={elem.description?elem.description.slice(0, 88): ""} url={elem.url} imgURL={elem.urlToImage} /> </div> })} </div> </div> </div> ) } }
P粉7247375112023-09-12 17:52:54
嗨 @Curious,你的代码是正确的
只需要在制作map
时注意一下
你正在使用this.articles
,这是一个固定(模拟)列表
你需要在this.state.articles
中调用map
,因为这是你在didMount中更改的状态
P粉3114649352023-09-12 16:04:16
this.articles
和 this.state.articles
不是相同的。
你有一个静态属性 this.articles
,你在渲染逻辑中使用了它 - this.articles.map(...
。你的 fetch 正在更新状态(正常操作)。
更新你的渲染逻辑,从 this.state.articles
读取数据,然后它应该可以工作。