Composable HTTP Client
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README.md

request-compose

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Composable HTTP Client

var compose = require('request-compose')
var Request = compose.Request
var Response = compose.Response

;(async () => {
  try {
    var {res, body} = await compose(
      Request.defaults({headers: {'user-agent': 'request-compose'}}),
      Request.url('https://api.github.com/users/simov'),
      Request.send(),
      Response.buffer(),
      Response.string(),
      Response.parse(),
    )()
    console.log(res.statusCode, res.statusMessage)
    console.log(res.headers['x-ratelimit-remaining'])
    console.log(body)
  }
  catch (err) {
    console.error(err)
  }
})()

Goals

  • No dependencies
  • No abstraction
  • No state

Table of Contents

Compose

In computer science, function composition (not to be confused with object composition) is an act or mechanism to combine simple functions to build more complicated ones. Like the usual composition of functions in mathematics, the result of each function is passed as the argument of the next, and the result of the last one is the result of the whole.

var compose = require('request-compose')

Accepts a list of functions to execute and returns a Promise:

var doit = compose(
  (a) => a + 2,
  (a) => a * 2,
)

Then we can call it:

var result = await doit(5) // 14

A more practical example however would be to compose our own HTTP client:

var compose = require('request-compose')
var https = require('https')

var request = compose(
  (options) => {
    options.headers = options.headers || {}
    options.headers['user-agent'] = 'request-compose'
    return options
  },
  (options) => new Promise((resolve, reject) => {
    https.request(options)
      .on('response', resolve)
      .on('error', reject)
      .end()
  }),
  async (res) => await new Promise((resolve, reject) => {
    var body = ''
    res
      .on('data', (chunk) => body += chunk)
      .on('end', () => resolve({res, body}))
      .on('error', reject)
  }),
  ({res, body}) => ({res, body: JSON.parse(body)}),
)

Then we can use it like this:

;(async () => {
  try {
    var {res, body} = await request({
      protocol: 'https:',
      hostname: 'api.github.com',
      path: '/users/simov',
    })
    console.log(res.statusCode, res.statusMessage)
    console.log(res.headers['x-ratelimit-remaining'])
    console.log(body)
  }
  catch (err) {
    console.error(err)
  }
})()

Bundled Middlewares

request-compose comes with a bunch of pre-defined middlewares for transforming the request and the response:

var compose = require('request-compose')
var Request = compose.Request
var Response = compose.Response

We can use these middlewares to compose our own HTTP client:

;(async () => {
  try {
    var {res, body} = await compose(
      Request.defaults({headers: {'user-agent': 'request-compose'}}),
      Request.url('https://api.github.com/users/simov'),
      Request.send(),
      Response.buffer(),
      Response.string(),
      Response.parse(),
    )()
    console.log(res.statusCode, res.statusMessage)
    console.log(res.headers['x-ratelimit-remaining'])
    console.log(body)
  }
  catch (err) {
    console.error(err)
  }
})()
Type Middleware Input Arguments Returns
Request defaults {input} {input} {options}
Request url, qs, cookie see options {options} {options}
Request form, json, multipart, body see options {options} {options, body}
Request auth, oauth see options {options, body} {options, body}
Request length - {options, body} {options, body}
Request send - {options, body} {options, res}
Response buffer - {options, res} {options, res, body}
Response gzip - {options, res, body, raw} {options, res, body, raw}
Response string see options {options, res, body, raw} {options, res, body, raw}
Response parse, status - {options, res, body, raw} {options, res, body, raw}
Response redirect (input, client) {options, res, body, raw} new composition

Opinionated Client

request-compose comes with opinionated HTTP client that is composed of the above middlewares.

There are 3 types of composition available based on the returned data type:

client

var request = require('request-compose').client
var {res, body} = await request({options})

The client composition does the following:

  • buffers the response body
  • decompresses gzip and deflate encoded bodies with valid content-encoding header
  • converts the response body to string using utf8 encoding by default
  • tries to parse JSON and querystring encoded bodies with valid content-type header

buffer

var request = require('request-compose').buffer
var {res, body} = await request({options})

The buffer composition returns the response body as raw Buffer.

stream

var request = require('request-compose').stream
var {res} = await request({options})

The stream composition returns the response Stream.

options

The above compositions accept any of the Node's http.request and https.request options:

var {res, body} = await request({
  method: 'GET',
  url: 'https://api.github.com/users/simov',
  headers: {
    'user-agent': 'request-compose'
  }
})

Additionally the following options are available:

Option Type Description
url 'string' url object URL (encoding - see below)
qs {object} 'string' URL querystring (encoding - see below)
form {object} 'string' application/x-www-form-urlencoded request body (encoding - see below)
json {object} 'string' JSON encoded request body
multipart {object} [array] multipart request body using request-multipart, see examples
body 'string' Buffer Stream request body
auth {user, pass} Basic authorization
oauth {object} OAuth authorization using request-oauth, see examples
encoding 'string' response body encoding (default: 'utf8')
cookie {object} cookie store using request-cookie, see examples
redirect {object} see below

Querystring set in the url, and/or in qs and/or in form as 'string' is left untouched, meaning that the proper encoding is left to the user.

When qs and/or form is {object} the querystring is encoded using the Node's querystring module which mirrors the global encodeURIComponent method. Additionally all reserved characters according to RFC3986 are encoded as well. Full list of all reserved characters that are being encoded can be found here.

redirect

Option Default Description
max 3 maximum number of redirects to follow
all false follow non-GET HTTP 3xx responses as redirects
method true follow original HTTP method, otherwise convert all redirects to GET
auth true keep Authorization header when changing hostnames
referer false add Referer header

extend

Extend or override any of the bundled request and response middlewares:

var request = require('request-compose').extend({
  Request: {
    oauth: require('request-oauth'),
    multipart: require('request-multipart'),
    cookie: require('request-cookie').Request
  },
  Response: {cookie: require('request-cookie').Response},
}).client

Errors

Non 200/300 responses are returned as Error object with the following properties:

  • message - status code + status message
  • res - the response object
  • body - the parsed response body
  • raw - the raw response body

Debug Logs

Fancy request-logs:

npm i --save-dev request-logs

Pick any of the following debug options:

DEBUG=req,res,body,json,nocolor node app.js

Examples

Basics

Topic Example
Types of lambda functions Get GitHub user profile
Bundled middlewares Get GitHub user profile
Wrap it up and extend it Get GitHub user profile

Compositions

Topic Example
Client Get GitHub user profile
Buffer Decoding response body using iconv-lite
Stream Stream Tweets

External Middlewares

Topic Example
OAuth (request-oauth) Get Twitter User Profile
Multipart (request-multipart) Upload photo to Twitter
Cookie (request-cookie) Login to Wallhaven.cc

Stream

Topic Example
Stream request body Upload file to Dropbox
HTTP stream Upload image from Dropbox to Slack
HTTP stream Copy file from Dropbox to GDrive

Misc

Topic Example
Gzip decompression Request Gzip compressed body
Override bundled middleware - per compose instance Override the qs middleware
Override bundled middleware - process-wide Override the form and the parse middlewares to use the qs module

Pipeline

Topic Example
App pipeline Slack Weather Status
App pipeline Simultaneously search for repos in GitHub, GitLab and BitBucket

Modules

Topic Example
Google Chrome Web Store HTTP Client chrome-webstore
wallhaven.cc HTTP Client wallhaven-client