React App：如何使用抓取显示来自api的数据

Question

我想使用React从外部API显示学校数据。我只是想显示一个学校名称开始。学校名称出现在控制台中，但不会显示在浏览器中.API调用是正确的，因为它在Postman中运行。这里是我的代码：

import React, { Component } from 'react'; 
import './App.css'; 

class App extends Component { 
    constructor(props) { 
    super(props); 
    this.state = { 
     schoolName: '', 
     // schoolData: {} 
    } 
    } 

    fetchSchool(event) { 
    event.preventDefault(); 

    const apiKey = 'XdOHSc8fKhMKidPu2HWqCZmMy9OxtCJamGC580Bi'; 
    const fields = `_fields=school.name,2015.aid.median_debt.completers.overall,2015.cost.tuition.in_state&school.name=${this.state.schoolName}`; 
    const requestUrl = `https://api.data.gov/ed/collegescorecard/v1/schools?&api_key=${apiKey}&${fields}`; 

    const school = fetch(requestUrl).then((res) => res.json()).then((data) => console.log(data.results[0]['school.name'])); 

    this.setState({ 
     schoolName: school 
     // schoolData: school 
    }) 
    console.log(this.state.schoolName); 
    } 

    setSchool(event) { 
    event.preventDefault(); 
    this.setState({ 
     schoolName: event.target.value 
    }); 
    } 

    render() { 
    // const schoolname = this.state.schoolName[0]; 
    // const {schooName} = this.state; 
    return (
     <div> 
     <form action="/school" method="GET" id="myform"> 
      <input type="text" className="form-control" id="enter_text" onChange={this.setSchool.bind(this)} /> 
      <button onClick={this.fetchSchool.bind(this)} type="submit" className="btn btn-primary" id="text-enter-button button submit">Submit</button> 
     </form> 
     <div> 
     <p>School: {this.state.school} </p> 
     </div> 
     </div> 
    ); 
    } 
} 

export default App; 

Answer 1

在渲染处理方法改变这一行，因为schoolName是你的状态变量，而不是school。

<p>School: {this.state.school} </p> 

到

<p>School: {this.state.schoolName} </p> 

Answer 2

fetch是异步的。因此，在获取数据之前调用setState。

要解决这个问题，从您的then函数内

const school = fetch(requestUrl) 
    .then((res) => res.json()) 
    .then((data) => { 
    console.log(data.results[0]['school.name']) 
    this.setState({ 
     schoolName: data.results[0]['school.name'], 
     schoolData: data.results 
    }) 
    });