Introducing a request library - How to use several Undici APIs

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Preface

In the browser, if we want to make a request, we used to use xhr, but this low-level API is often called in a simple way. In order to improve development efficiency, jQuery's $.ajax may be the best choice. Fortunately, a more modern fetch api appeared later.

However, considering the compatibility of fetch, and the fact that it does not support some global configurations and request interruption, in actual use, we may use the axios request library to make some requests. In Node.js, almost all requests are made through the request library. Unfortunately, request stopped maintenance two years ago, and it is not easy to find a replacement library in Node.js.

In the request issues[1], there is a table that recommends some commonly used request libraries in Node.js:

Axios, which is widely used in browsers, is not easy to use in Node.js, especially when uploading files, there will be many unexpected problems.

Recently, when I was surfing the Internet, I found that Node.js officially has a request library: undici. The name is quite complicated. So, today's article will introduce undici. By the way, undici means 11 in Italian. It seems that Double 11 is coming soon, which is good for Moutai.

• Undici means eleven in Italian. 1.1 -> 11 -> Eleven -> Undici. It is also a Stranger Things reference.

Get Started

We can install undici directly through npm:

 npm install undici -S

undici exposes an object to the outside world, which provides several APIs:

• undici.fetch: initiates a request, which is consistent with the fetch method in the browser;
• undici.request: initiates a request, which is somewhat similar to the request library. This method supports Promise;
• undici.stream: processes file streams and can be used to download files;

undici.fetch

Note: This method requires node version >= v16.5.0

Before requesting the service through undici.fetch, you need to start a simple login service through koa.

 const Koa = require( 'koa' )
 const bodyParser = require( 'koa-bodyparser' ) 
 
 const app = new Koa() 
 
 app.use(bodyParser())
 app.use(ctx => {
  const { url, method, body } = ctx.request
 if (url === '/login' ) {
 if (method === 'POST' ) {
      if (body.account === 'shenfq' && body. password === '123456' ) {
        ctx.body = JSON.stringify({
 name : 'shenfq' ,
 mobile: '130xxxxxx'  
 })
 return  
 }
 }
 }
 ctx.status = 404
  ctx.body = JSON.stringify({})
 }) 
 
 app.listen(3100)

The above code is very simple and only supports accepting a POST method to the /login route. Next, we use undici.fetch to initiate a POST request.

 const { fetch } = require( 'undici' ) 
 
 const bootstrap = async () => {
  const api = 'http://localhost:3100/login'  
  const rsp = await fetch (api, {
 method: 'POST' ,
 headers: {
 'content-type' : 'application/json'  
 },
 body: JSON.stringify({
 account: 'shenfq' ,
 password : '123456'  
 })
 })
 if (rsp.status !== 200) {
 console.log(rsp.status, 'Request failed' )
 return  
 }
  const json = await rsp.json()
  console.log(rsp.status, json)
 } 
 
 bootstrap()

If the request method is changed to GET, 404 will be returned.

 const rsp = await fetch (api, {
 method: 'GET'  
 })

undici.request

The calling method of undici.request is similar to undici.fetch, and the parameter passing format is also similar .

 const { request } = require( 'undici' ) 
 
 const bootstrap = async () => {
  const api = 'http://localhost:3100/login'  
  const { body, statusCode } = await request(api, {
 method: 'POST' ,
 headers: {
 'content-type' : 'application/json'  
 },
 body: JSON.stringify({
 account: 'shenfq' ,
 password : '123456'  
 })
 })
  const json = await body.json()
  console.log(statusCode, json)
 } 
 
 bootstrap()

The only difference is that the returned result is a little different. The http response result returned by the request method is in the body attribute, and this attribute also supports methods such as .json()/.text() similar to fetch.

Interrupt Request

Install the abort-controller library, then instantiate the abort-controller and pass the interrupt signal into the request configuration.

 npm i abort-controller

 const undici = require( 'undici' )
 const AbortController = require( 'abort-controller' ) 
 
 // Instantiate abort-controller
 const abortController = new AbortController()
 undici.request( 'http://127.0.0.1:3100' , {
 method: 'GET' ,
 //Incoming interrupt signal
  signal: abortController.signal,
 }). then (({ statusCode, body }) => {
  body. on ( 'data' , (data) => {
    console.log(statusCode, data.toString())
 })
 })

We run the code and find that the request is successful because we did not actively call the interrupt method.

 undici.request( 'http://127.0.0.1:3100' , {
 method: 'GET' ,
  signal: abortController.signal,
 }). then (({ statusCode, body }) => {
 console.log( 'Request successful' )
  body. on ( 'data' , (data) => {
    console.log(statusCode, data.toString())
 })
 }).catch(error => {
 // Capture errors triggered by interrupts
  console.log( 'error' , error. name )
 }) 
 
 //Call interrupt
 abortController.abort()

Now when you run the code, you will find that there is no log of successful request output. The catch logic is entered and the request is successfully interrupted.

undici.steam

The undici.steam method can be used to download files or interface proxy.

Download the file

 const fs = require( 'fs' )
 const { stream } = require( 'undici' ) 
 
 const out = fs.createWriteStream( './Song Dynasty-Ge Kiln-Gold Wire and Iron Wire.jpg' )
 const url = 'https://img.dpm.org.cn/Uploads/Picture/dc/cegift/cegift6389.jpg'   
 
 stream(url, { opaque: out }, ({ opaque }) => opaque)

Interface Proxy

 const http = require( 'http' )
 const undici = require( 'undici' ) 
 
 // Proxy requests from port 3100 to port 80
 const client = new undici.Client( 'http://localhost' )
 http.createServer((req, res) => {
 const { url, method } = req
 client.stream(
    { method, path: url,opaque: res },
 ({ opaque }) => opaque
 )
 }).listen(3100)

Summarize

This article only introduces the usage of several undici APIs. It seems that the ease of using undici is still relatively low. However, the compatibility is not very good. For example, fetch only supports [email protected] and above.

For this kind of relatively new library, I personally recommend waiting for a while. Although request has been abandoned, we still use some time-tested libraries, such as urllib[7] used in the egg framework, and node-fetch[8], which is relatively easy to use and is used in the same way as the fetch API in the browser.

References

[1]issues: https://github.com/request/request/issues/3143

[2]node-fetch: https://www.npmjs.com/package/node-fetch

[3]got: https://www.npmjs.com/package/got

[4]axios: https://www.npmjs.com/package/axios

[5]superagent: https://www.npmjs.com/package/superagent

[6]urllib: https://www.npmjs.com/package/urllib

[7]urllib: https://www.npmjs.com/package/urllib

[8]node-fetch: https://www.npmjs.com/package/node-fetch