How to handle vue axios request timeout

This time I will bring you how to deal with vue axios request timeout, what are the precautions when dealing with vue axios request timeout, the following is a practical case, let's take a look.

Since using Vue2, I have used the officially recommended axios plug-in to call the API. During use, if the server or network is unstable and packets are dropped, how should you deal with it? Let me share with you what I have done experience.

Specific reasons

The company is currently working on a project. The server-side data interface uses the API output by Php. Sometimes it is called The process will fail, and Provisional headers are shown in Google Chrome.

According to the solutions given by the search engine, my problem cannot be solved.

I have recently been studying the concept of AOP development and programming, which is in the axios development instructions. The mentioned interceptors (axios.Interceptors) should be this mechanism, which reduces code coupling, improves program reusability, and improves development efficiency.

Solution 1 with pitfalls

My experience is limited and I think the only thing I can do is to make a new request after the axios request times out. . By studying the instructions for use of axios, set a timeout = 6000

axios.defaults.timeout = 6000;

and then add a column cutter.

// Add a request interceptor
axios.interceptors.request.use(function (config) {
 // Do something before request is sent
 return config;
 }, function (error) {
 // Do something with request error
 return Promise.reject(error);
});
// Add a response interceptor
axios.interceptors.response.use(function (response) {
 // Do something with response data
 return response;
 }, function (error) {
 // Do something with response error
 return Promise.reject(error);
});

The function of this column cutter is if the request times out, the column cutter You can capture the information and then proceed to the next step, that is, I want to re-request.

Here are the relevant page data requests.

this.$axios.get(url, {params:{load:'noload'}}).then(function (response) {
	//dosomething();
}).catch(error => {
	//超时之后在这里捕抓错误信息.
	if (error.response) {
		console.log('error.response')
		console.log(error.response);
	} else if (error.request) {
		console.log(error.request)
		console.log('error.request')
		if(error.request.readyState == 4 && error.request.status == 0){
			//我在这里重新请求
		}
	} else {
		console.log('Error', error.message);
	}
	console.log(error.config);
});

After the timeout, the error Uncaught (in promise) Error: timeout of xxx ms exceeded is reported.

In catch, it returns an error.request error, so the retry function is done here. After testing, the re-request function can be realized. Although it can It implements the function of re-requesting after timeout, but it is very troublesome. It requires setting the re-request in every page that requests the API.

Looking at the above, my project has dozens of .vue files. If every page has to set the timeout and re-request function, then I will go crazy.

And this mechanism also has a serious bug, that is, when the requested link fails or cannot be accessed normally due to other reasons, this mechanism fails. It will not wait for the 6 seconds I set, and it will continue to When brushing, dozens of requests per second can easily bring down the server. Please see the picture below. In the blink of an eye, it requests 146 times.

Solution 2 with pitfalls

After studying the source code of axios, after timeout, The error message is caught in axios.interceptors.response in the interceptor, and error.code = "ECONNABORTED", specific link

https://github.com/axios/axios/blob/26b06391f831ef98606ec0ed406d2be1742e9850/lib/ adapters/xhr.js#L95-L101

// Handle timeout
 request.ontimeout = function handleTimeout() {
  reject(createError('timeout of ' + config.timeout + 'ms exceeded', config, 'ECONNABORTED',
  request));
  // Clean up request
  request = null;
 };

So, my solution for global timeout retrieval is like this.

axios.interceptors.response.use(function(response){
....
}, function(error){
	var originalRequest = error.config;
	if(error.code == 'ECONNABORTED' && error.message.indexOf('timeout')!=-1 && !originalRequest._retry){
			originalRequest._retry = true
			return axios.request(originalRequest);
	}
});

This method can also implement new requests, but there are two problems. 1. It only re-requests once. If it times out again, it will stop and will not request again. The second problem is that I do many operations on each page with data requests, such as operations after this.$axios.get(url).then.

Perfect solution

In AOP programming, what I need is a global function that re-requests with timeout, to be in axios.Interceptors After working hard, I looked for some solutions from others in the axios issue on github, and finally found a perfect solution, which is the one below.

https://github.com/axios/axios/issues/164#issuecomment-327837467

//在main.js设置全局的请求次数，请求的间隙
axios.defaults.retry = 4;
axios.defaults.retryDelay = 1000;
axios.interceptors.response.use(undefined, function axiosRetryInterceptor(err) {
 var config = err.config;
 // If config does not exist or the retry option is not set, reject
 if(!config || !config.retry) return Promise.reject(err);
 // Set the variable for keeping track of the retry count
 config.retryCount = config.retryCount || 0;
 // Check if we've maxed out the total number of retries
 if(config.retryCount >= config.retry) {
  // Reject with the error
  return Promise.reject(err);
 }
 // Increase the retry count
 config.retryCount += 1;
 // Create new promise to handle exponential backoff
 var backoff = new Promise(function(resolve) {
  setTimeout(function() {
   resolve();
  }, config.retryDelay || 1);
 });
 // Return the promise in which recalls axios to retry the request
 return backoff.then(function() {
  return axios(config);
 });
});

The other dozens of .vue pages this.$axiosThe get and post methods do not need to modify their code at all.

在这个过程中，谢谢jooger给予大量的技术支持，这是他的个人信息  https://github.com/jo0ger  ， 谢谢。

以下是我做的一个试验。。把axios.defaults.retryDelay = 500, 请求 www.facebook.com

如有更好的建议，请告诉我，谢谢。

补充：

axios基本用法

vue更新到2.0之后，作者就宣告不再对vue-resource更新，而是推荐的axios,前一段时间用了一下，现在说一下它的基本用法。

首先就是引入axios,如果你使用es6，只需要安装axios模块之后

import axios from 'axios';
//安装方法
npm install axios
//或
bower install axios

当然也可以用script引入

axios提供了一下几种请求方式

axios.request(config)
axios.get(url[, config])
axios.delete(url[, config])
axios.head(url[, config])
axios.post(url[, data[, config]])
axios.put(url[, data[, config]])
axios.patch(url[, data[, config]])

这里的config是对一些基本信息的配置，比如请求头，baseURL，当然这里提供了一些比较方便配置项

//config
import Qs from 'qs'
{
 //请求的接口，在请求的时候，如axios.get(url,config);这里的url会覆盖掉config中的url
 url: '/user',
 // 请求方法同上
 method: 'get', // default
 // 基础url前缀
 baseURL: 'https://some-domain.com/api/',
　　
　　　　
 transformRequest: [function (data) {
  // 这里可以在发送请求之前对请求数据做处理，比如form-data格式化等，这里可以使用开头引入的Qs（这个模块在安装axios的时候就已经安装了，不需要另外安装）
　　data = Qs.stringify({});
  return data;
 }],
 transformResponse: [function (data) {
  // 这里提前处理返回的数据
  return data;
 }],
 // 请求头信息
 headers: {'X-Requested-With': 'XMLHttpRequest'},
 //parameter参数
 params: {
  ID: 12345
 },
 //post参数，使用axios.post(url,{},config);如果没有额外的也必须要用一个空对象，否则会报错
 data: {
  firstName: 'Fred'
 },
 //设置超时时间
 timeout: 1000,
 //返回数据类型
 responseType: 'json', // default
}

有了配置文件，我们就可以减少很多额外的处理代码也更优美，直接使用

axios.post(url,{},config)
  .then(function(res){
    console.log(res);
  })
  .catch(function(err){
    console.log(err);
  })
//axios请求返回的也是一个promise,跟踪错误只需要在最后加一个catch就可以了。
//下面是关于同时发起多个请求时的处理
axios.all([get1(), get2()])
 .then(axios.spread(function (res1, res2) {
  // 只有两个请求都完成才会成功，否则会被catch捕获
 }));

最后还是说一下配置项，上面讲的是额外配置，如果你不想另外写也可以直接配置全局

axios.defaults.baseURL = 'https://api.example.com';
axios.defaults.headers.common['Authorization'] = AUTH_TOKEN;
axios.defaults.headers.post['Content-Type'] = 'application/x-www-form-urlencoded';
//当然还可以这么配置
var instance = axios.create({
 baseURL: 'https://api.example.com'
});

本文只是介绍基本的用法，详细看官方文档https://github.com/axios

我写的两个例子：

使用vue2.0+mintUI+axios+vue-router: https://github.com/Stevenzwzhai/vue-mobile-application

使用vue2.0+elementUI+axios+vue-router: https://github.com/Stevenzwzhai/vue2.0-elementUI-axios-vueRouter, 之前由于没做后端接口，所以运行没数据，现在加了mockjs来返回一些数据，以便于参考。

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