javascript 状态更改后组件未更改(componentDidMount获取)- React

eit6fx6z  于 2023-02-02  发布在  Java
关注(0)|答案(2)|浏览(101)

我正在按照教程制作一个新闻应用程序我正在从newapi获取数据我的代码看起来与教程相同,但我的组件在我更新状态(this.state.articles)后没有更改我正在使用setState函数我尝试控制台记录状态在状态更新后它看起来很好渲染方法运行,但它没有更改任何可能发生的错误
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>
        )
    }
}
rslzwgfq

rslzwgfq1#

this.articlesthis.state.articles不相同。
您有一个静态属性this.articles,您正在渲染逻辑中使用它-this.articles.map(...。您的获取正在更新状态(就像它应该的那样)。
更新你的渲染从this.state.articles读取,它应该工作。

ybzsozfc

ybzsozfc2#

您输入的代码正确
map的时候你只需要注意
您正在使用this.articles,这是一个固定(模拟)列表
您需要在this.state.articles中调用map,因为这是您在didMount中更改的状态

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