Create an object from a flattenObject.

objectFromFlatten.js

/**
 * Creates an object from a flattenObject.
 *
 * @example
 *
 * Create following object:
 *
 * {
 *    address: {
 *      city: {
 *        name: 'São Paulo'
 *      },
 *      state: {
 *        name: 'SP'
 *      },
 *      street: {
 *        number: 123,
 *        name: 'Gustave Rapin'
 *      }
 *    }
 * }
 *
 * From this object:
 *
 * {
 *    'address.city.name': 'São Paulo',
 *    'address.state.name': 'SP',
 *    'address.street.number': 123,
 *    'address.street.name': 'Gustave Rapin',
 * }
 *
 * @param  {object} input
 * @param  {stirng} divider
 * @return {object}
 */
export function objectFromFlatten(input, divider = '.') {
  const object = {}

  const appendNestedField = (nests, name, value) => {
    let pointer = object

    if (nests && nests.length) {
      nests.forEach((nest) => {
        if (!pointer[nest]) {
          pointer[nest] = {}
        }
        pointer = pointer[nest]
      })
    }

    pointer[name] = value
  }

  Object.keys(input).forEach((key) => {
    const nests = key.split(divider)
    const name = nests.pop()
    const value = input[key]

    appendNestedField(nests, name, value)
  })

  return object
}