Transforming Deeply Nested Data

TransformingDeeplyNestedData.js

import {
  always,
  equals,
  identity,
  ifElse,
  map,
  partial,
} from 'ramda'

const isObject = input => input !== null && typeof input === 'object'

/**
 * Like map but for deeply nested objects
 *
 * @param {Function} f function to apply
 * @param {Object} obj
 */
const nestedMap = (f, obj) => map(ifElse(isObject, partial(nestedMap, [f]), f), obj)

// verify
nestedMap(x => x + 5, [1, [[[2]]]])
// [
//   6,
//   [
//     [
//       [
//          7
//       ]
//     ]
//   ]
// ]

nestedMap(x => x + 5, {a: 1, b: { c: { d: 2 }}})
// {"a":6,"b":{"c":{"d":7}}}

const inputData = { a: 1, b: { c: { d: 2 } }, e: null, f: 3 }

const outputData = { a: 1, b: { c: { d: 2 } }, e: '', f: 3 }

const transformFrom = data => nestedMap(ifElse(equals(null), always(''), identity), data)

const transformTo = data => nestedMap(ifElse(equals(''), always(null), identity), data)

console.log(equals(transformTo(transformFrom(inputData)), inputData))

console.log(equals(transformFrom(transformTo(outputData)), outputData))