How to request data with react fetch

React fetch request data method: 1. Place the requested method in the "componentDidMount" of the life cycle; 2. Encapsulate the fetch request; 3. Pass "function checkStatus(response){...}" Method to check the request status; 4. Use the encapsulated request and print the result on the server or browser.

#The operating environment of this tutorial: Windows 10 system, react16 version, Dell G3 computer.

How does react fetch request data?

React Fetch request

I need to use it recently, so learn it

1.fetch

Promise-based ajax Request

https://developer.mozilla.org/zh-CN/docs/Web/API/Fetch_API

2. React uses fetch

The request method is generally put In componentDidMount of the life cycle

Basic format of requested data

import React from 'react'
class RequestStu extends React.Component{
  constructor(props){
    super(props)
    this.state={
      test:{},
      arr:[]
    }
  }
  componentDidMount(){
    fetch('http://localhost/console/scene/scenedetaillist',{
      method:'GET',
      headers:{
        'Content-Type':'application/json;charset=UTF-8'
      },
      mode:'cors',
      cache:'default'
    })
     .then(res =>res.json())
     .then((data) => {
       console.log(data)  
       this.setState({
         test:data
       },function(){
         console.log(this.state.test)
         let com = this.state.test.retBody.map((item,index)=>{
           console.log(item.id)
           return <li key={index}>{item.name}</li>
         })
         this.setState({
           arr : com
         },function(){
           console.log(this.state.arr)
         })
       })
     }) 
  }
  render(){
    return (
      <div>
       <ul>
          {
            this.state.arr
          }
       </ul>
      </div>
    )
  }
}
export default RequestStu

Displayed after request:

3. Encapsulate fetch request

Encapsulate it for easy calling

Code address: https://github.com/klren0312/react_study/blob/master/stu13/src/helper.js

helper.js

//全局路径
const commonUrl = 'http://127.0.0.1:3456'
//解析json
function parseJSON(response){
  return response.json()
}
//检查请求状态
function checkStatus(response){
  if(response.status >= 200 && response.status < 500){
    return response
  }
  const error = new Error(response.statusText)
  error.response = response
  throw error
}
export default  function request(options = {}){
  const {data,url} = options
  options = {...options}
  options.mode = &#39;cors&#39;//跨域
  delete options.url
  if(data){
    delete options.data
    options.body = JSON.stringify({
      data
    })
  }
  options.headers={
    &#39;Content-Type&#39;:&#39;application/json&#39;
  }
  return fetch(commonUrl+url,options,{credentials: &#39;include&#39;})
    .then(checkStatus)
    .then(parseJSON)
    .catch(err=>({err}))
}

Use encapsulated requests

import React from 'react'
import request from './helper.js'
class RequestDemo extends React.Component{
  componentDidMount(){
    request({
      url:'/posttest',
      method:'post',
      data:{"Header":{"AccessToken":"eyJ0eXBlIjoiSldUIiwiYWxnIjoiSFM1MTIifQ.eyJzdWIiOiIxMDYiLCJleHBpciI6MTUxMDczODAzNjA5MiwiaXNzIjoiIn0.eo000vRNb_zQOibg_ndhlWbi27hPt3KaDwVk7lQiS5NJ4GS4esaaXxfoCbRc7-hjlyQ8tY_NZ24BTVLwUEoXlA"},"Body":{}}
    }).then(function(res){
      console.log(res)
    })
  }
  render(){
    return (
      <div>
    test
      </div>
    )
  }
}
export default RequestDemo

Server printing

Browser printing

Comes with a bonus helper class

function parseJSON(response){
  return response.json()
}
function checkStatus(response){
  if(response.status >= 200 && response.status < 500){
    return response
  }
  const error = new Error(response.statusText)
  error.response = response
  throw error
}
/**
 * 登录请求
 * 
 * @param data 数据
 */
export function loginReq(data){ 
  const options = {}
  options.method = &#39;post&#39;
  options.made = &#39;cors&#39;
  options.body = JSON.stringify(data)
  options.headers={
    &#39;Content-Type&#39;:&#39;application/json&#39;
  }
  return fetch(&#39;/loginOk&#39;,{ ...options, credentials:&#39;include&#39;})
    .then(checkStatus)
    .then(parseJSON)
    .then((res)=>{
      if(res.retCode === &#39;0001&#39;){
        localStorage.setItem(&#39;x-access-token&#39;,res.retBody.AccessToken)
        return &#39;success&#39;
      }
      else if(res.retCode === &#39;0002&#39;){
        return &#39;error&#39;
      }
      else if(res.retCode === &#39;0003&#39;){
        return &#39;error&#39;
      }else{
        return ;
      }
      
    })
    .catch(err=>({err}))
}
/**
 * 普通请求
 * @param {*url,*method,*data} options 
 */
export  function request(options = {}){
  const Authorization = localStorage.getItem(&#39;x-access-token&#39;)
  const {data,url} = options
  options = {...options}
  options.mode = &#39;cors&#39;
  delete options.url
  if(data){
    delete options.data
    options.body = JSON.stringify(data)
  }
  options.headers={
    &#39;x-access-token&#39;:Authorization,
    &#39;Content-Type&#39;:&#39;application/json;charset=UTF-8&#39;
  }
  return fetch(url,{ ...options, credentials: &#39;include&#39;})
    .then(checkStatus)
    .then(parseJSON)
    .catch(err=>({err}))
}

Recommended learning: "react video tutorial"

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