JSON REST API Client for Node.js

Motivation

In my search for a simple and concise client library for HTTP REST APIs, none of the npm modules that I found satisfied the criteria I was looking for:

• Concise
• Easy to read and use
• Promises
• No unnecessary dependencies
• No unnecessary HTTP abstractions

This client aims to satisfy all those criteria. Enjoy!

A Note on JSON and UTF-8

JRAC JSON-encodes the body of all requests using JSON.stringify, and assumes all request data to be provided in UTF-8. As such, it sets the Content-Type header of all requests to application/json; charset=utf-8 by default:

if (!headers.hasOwnProperty('Content-Type') && !headers.hasOwnProperty('content-type')) {
  headers['Content-Type'] = 'application/json; charset=utf-8';
}
if (!headers.hasOwnProperty('Content-Length') && !headers.hasOwnProperty('content-length')) {
  headers['Content-Length'] = Buffer.byteLength(body, 'utf8');
}

As you can see, you can override that behaviour by specifying Content-Type and/or Content-Length headers per-request (or for all requests via the class constructor argument).

On the receiving side, JRAC indicates to the server that all responses should be JSON-encoded. This can be overriden in the same manner:

if (!headers.hasOwnProperty('Accept') && !headers.hasOwnProperty('accept')) {
  headers['Accept'] = 'application/json';
}

Installation

npm install jrac --save

Usage

ES6

import {RestApiClient, RestApiResponse} from 'jrac';

var booksApi = new RestApiClient('https://www.googleapis.com/books/v1');
booksApi
  .get('volumes', {q: 'isbn:0307400840'})
  .then(response => {
    // response is an instance of RestApiResponse
  })
  .catch(result => {
    if (result instanceof RestApiResponse) {
      // result.statusCode is >= 400
    } else {
      // Instance of Error. See https://nodejs.org/docs/latest/api/errors.html
    }
  });

ES5

var RestApiClient = require('jrac').RestApiClient;
var RestApiResponse = require('jrac').RestApiResponse;

var booksApi = new RestApiClient('https://www.googleapis.com/books/v1');
booksApi
  .get('volumes', {q: 'isbn:0307400840'})
  .then(function (response) {
    // response is an instance of RestApiResponse
  })
  .catch(function (result) {
    if (result instanceof RestApiResponse) {
      // result.statusCode is >= 400
    } else {
      // Instance of Error. See https://nodejs.org/docs/latest/api/errors.html
    }
  });

Reference

RestApiResponse

RestApiResponse {
    statusCode: {number} HTTP status code
    headers: {Object} HTTP response headers. All keys are lower-case.
    data: {Object} The JSON-decoded response body
    rawBody: {String} If JSON-decoding of the response body fails, this property will contain it un-parsed
}

RestApiClient

constructor (apiUrl, keepConnectionAlive = false, headers = {})

• apiUrl accepts any valid URL, including port and query string. Query string parameters present in this URL are added as defaults to the URLs of all requests. Defaults are overwritten by equally named query string parameters passed into an individual request.
• If keepConnectionAlive is set to true, the connection to the server is kept open between requests.
• headers: Headers to be added to every request. Can be overwritten in individual requests.

The methods provided by this class map to HTTP methods, each of which returns a promise.

• get (path, queryStringParams = {}, headers = {})
• post (path, requestBodyParams = {}, headers = {})
• put (path, requestBodyParams = {}, headers = {})
• patch (path, requestBodyParams = {}, headers = {})
• delete (path, requestBodyParams = {}, headers = {})

The promise is resolved with an instance of RestApiResponse if the response has a status code that is smaller than 400. The promise is rejected with an instance of RestApiResponse if the response has a status code that is 400 or higher.

If an error occurs, the promise is rejected with an instance of Error. See https://nodejs.org/docs/latest/api/errors.html for details.