merge-objects

Simple library to merge an arbritary number of objects together preserving getter and setter methods.

Background

Object.assign and the spread operator only get you so far when you are trying to merge objects that contain getter and setter methods like:

const person = {
  firstName: null,
  lastName: null,

  get name() {
    return `${this.firstName} ${this.lastName}`
  },
  set name(newName) {
    const [firstName, lastName] = newName.split(' ')

    this.firstName = firstName
    this.lastName = lastName
  },
}

If we wanted to create a clone of this we might think to use:

const person2 = Object.assign({}, person)

but when we do this person2 has a simple key based value for name not the dynamic value linked to firstName and lastName as person.

e.g.

> person.name = 'Iain Donaldson'
'Iain Donaldson'
> person
{ firstName: 'Iain', lastName: 'Donaldson', name: [Getter/Setter] }
> person2
{ firstName: 'Iain', lastName: 'Donaldson', name: 'Iain Donaldson' }

Using the spread operator results in the same thing, e.g.

const person3 = { ...person }

person3 now has keys that reflect the values of the getter in person and not the getter and setter methods themselves.

This package allwows you to combine objects that include getter/setter methods simply.

Usage

Usage of this package is straightforward, e.g.:

import mergeObjects from '@iainad/merge-objects'

const person = {
  firstName: null,
  lastName: null,

  get name() {
    return `${this.firstName} ${this.lastName}`
  },

  set name(newName) {
    const [firstName, lastName] = newName.split(' ')

    this.firstName = firstName
    this.lastName = lastName
  },
}

const address = {
  houseNumber: 10,
  streetName: 'Town Road',
  town: 'Townville',
  zip: '12233',
}

const mergedPerson = mergeObjects(person, address)

In the above example the new object will be the combination of the objects but maintains the getter and setter methods for the name as in the original object.

Credits

Most of the actually useful code here comes from @joelmoss in ibiza React 'state management for party animals' so thanks Joel!

I wanted this to allow me to destructure models in Ibiza as follows:

import mergeObjects from '@iainad/merge-objects'
import { createModel } from 'ibiza'

const modelAccessors = {
  get name() {
    return `${this.firstName} ${this.lastName}`
  },
  set name(newName) {
    const [firstName, lastName] = newName.split(' ')

    this.firstName = firstName
    this.lastName = lastName
  },
}

const modelActions = {
  clearName() {
    this.firstName = ''
    this.lastName = ''
  },
}

const modelInitialProps = {
  firstName: null,
  lastName: null,
}

const model = createModel('model.mount.path', (_, runtimeProps) =>
  mergeObjects(modelInitialProps, modelAccessors, modelActions, runtimeProps)
)

export default model

This allows creation of more complex models with getters, setters and actions but not having to have them all in the same model defintion file.

TODO

Add some tests!