Analysis of Vue and server-side communication: how to handle concurrent requests

Analysis of Vue and server-side communication: How to handle concurrent requests

Introduction:
When developing front-end applications, it is very common to communicate with the server need. When developing using the Vue framework, we usually use tool libraries such as axios or fetch to send HTTP requests. However, when dealing with concurrent requests, we need to pay attention to how to handle these requests reasonably to avoid problems. This article will use code examples to explain how to handle concurrent requests when Vue communicates with the server.

1. Scenario of sending concurrent requests
When a page needs to send multiple requests at the same time, we can choose to send these requests concurrently to improve the page loading speed and optimize the user experience. This scenario is common in backend management systems or data report display pages, such as obtaining user lists, order lists, product lists, etc. at the same time.

2. Example of using axios to send requests concurrently
In the Vue project, we can use the axios library to send HTTP requests. The following is a sample code that uses axios to send requests concurrently:

import axios from 'axios';

// 创建axios实例
const instance = axios.create({
  baseURL: 'http://api.example.com',
  timeout: 5000
});

// 请求1
const request1 = instance.get('/users');
// 请求2
const request2 = instance.get('/orders');
// 请求3
const request3 = instance.get('/products');

// 并发发送请求
axios.all([request1, request2, request3]).then(axios.spread(function (res1, res2, res3) {
  // 请求1的响应数据
  console.log(res1.data);
  // 请求2的响应数据
  console.log(res2.data);
  // 请求3的响应数据
  console.log(res3.data);
})).catch(function (error) {
  console.log(error);
});

In the above code, we first create an axios instance through the axios.create method, and set the base URL and request timeout time. Then, we sent three requests through this instance to obtain the user list, order list, and product list respectively.

Then, we use the axios.all method to pass in these three requests as parameters, and use the axios.spread method to deconstruct the response data and get them respectively. Response data to each request.

3. Errors in handling concurrent requests
When sending concurrent requests, any request may go wrong. We need to ensure that even if an error occurs in one of the requests, the other requests can return normally, and error handling can be performed according to specific needs. The following is a sample code for handling concurrent request errors:

axios.all([request1, request2, request3]).then(axios.spread(function (res1, res2, res3) {
  // 请求1的响应数据
  console.log(res1.data);
  // 请求2的响应数据
  console.log(res2.data);
  // 请求3的响应数据
  console.log(res3.data);
})).catch(function (error) {
  if (axios.isCancel(error)) {
    console.log('请求被取消');
  } else {
    console.log('请求发生错误');
    console.log(error);
  }
});

In the above code, we use the axios.isCancel method to determine whether it is an error that the request was canceled. If so, it will output "The request was canceled" Cancel", otherwise output "An error occurred during the request" and print the error message.

4. Cancellation of Request
In some scenarios, we may want to cancel an ongoing request. For example, when the user enters a request in the search box, we can cancel the previous search request when the input box changes and only send the latest search request. Here is a sample code for requesting cancellation:

let cancel;

// 取消请求
function cancelRequest() {
  if (typeof cancel === 'function') {
    cancel('请求被取消');
  }
}

// 发送请求
function sendRequest() {
  cancelRequest();

  // 创建新的取消令牌
  const source = axios.CancelToken.source();

  // 发送请求
  axios.get('/search', {
    cancelToken: source.token
  }).then(function (res) {
    console.log(res.data);
  }).catch(function (error) {
    if (axios.isCancel(error)) {
      console.log('请求被取消');
    } else {
      console.log('请求发生错误');
      console.log(error);
    }
  });

  // 存储取消令牌
  cancel = source.cancel;
}

In the above code, we create a cancellation token through the axios.CancelToken.source method and pass it to the requested cancelTokenParameters. Before sending a new request, we call the cancelRequest method to cancel the previous request. At the same time, we assign the cancel method in the cancellation token to the cancel variable so that it can be called when the request needs to be canceled.

Conclusion:
This article explains how to use the axios library to handle concurrent requests in Vue, and gives corresponding sample code. In actual development, when the page needs to send multiple requests at the same time, we can use concurrent requests to optimize the user experience. At the same time, you need to pay attention to errors that may occur when processing concurrent requests, and perform corresponding request cancellation processing according to specific needs. I hope this article can help you handle concurrent requests when Vue communicates with the server.

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