Index By Key

A curried function using Ramda that transforms an array of objects into an object of objects, where the key is the key specified and the value is the rest of the object. The function will return a new object and will not mutate or destroy the original array.

Install

yarn

yarn add @juliancoleman/index-by-key

npm

npm i -S @juliancoleman/index-by-key

Setup

This package provides the single function mentioned above. You can specify the key on require, or you can specify a key to indexBy later on.

// initialize without specified key
const indexByKey = require("@juliancoleman/index-by-key");

// initialize with specified key at require
const indexById = require("@juliancoleman/index-by-key")("id");

// initialize with specified key later
const indexByFirstName = indexByKey("first_name");

Once required and a key is specified, you can then call the function on your data to see the transformation. Again, the function will return a new object and will not mutate or destroy the original array.

Below is an example use on a Promise object returned by an asynchronous database call:

const indexByKey = require("@juliancoleman/index-by-key");

const { getUsers } = appRequire("path/to/API");

(async () => {
  const indexById = indexByKey("id");
  const users = await getUsers();

  /*
  Example `users`

  [ { "id": 1,
      "first_name": "Julian",
      "last_name": "Coleman",
      "email_address": "[email protected]" },
    { "id": 2,
      "first_name": "Bob",
      "last_name": "Sagget",
      "email_address": "[email protected]" } ]
  */

  if (!users) {
    throw new Error("Unable to retrieve users");
  }

  return indexById(users);

})();

/*
results in the following output

  { "1": { "first_name": "Julian",
           "last_name": "Coleman",
           "email_address": "[email protected]"
         },
    "2": { "first_name": "Bob",
           "last_name": "Sagget",
           "email_address": "[email protected]" } }
*/

Alternatively, this same thing can be achieved by doing the following:

API.getUsers().then(indexByKey("id"));