request-compose

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
• Bundled Middlewares
• Opinionated Client
  • client / buffer / stream / options / extend
• Errors
• Debug Logs
• Examples

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, proxy, 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

Returns either String or Object.

buffer

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

The buffer composition does the following:

• buffers the response body
• decompresses gzip and deflate encoded bodies with valid content-encoding header

Returns 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)
proxy	'string' url object	Proxy URL
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 1.0a 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 thrown 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
HTTPS proxy	Tunnel Agent
HTTPS proxy	Proxy Agent
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
REST API Client Library	purest