Removing object properties with Lodash

Question

I have to remove unwanted object properties that do not match my model. How can I achieve it with Lodash?

My model is:

var model = {
   fname: null,
   lname: null
}

My controller output before sending to the server will be:

var credentials = {
    fname: "xyz",
    lname: "abc",
    age: 23
}

If I use

 _.extend(model, credentials)

I am getting the age property too. I am aware I can use

delete credentials.age

but what if I have more than 10 unwanted objects? Can I achieve it with Lodash?

Answer 1

You can approach it from either an "allow list" or a "block list" way:

// Block list
// Remove the values you don't want
var result = _.omit(credentials, ['age']);

// Allow list
// Only allow certain values
var result = _.pick(credentials, ['fname', 'lname']);

If it's reusable business logic, you can partial it out as well:

// Partial out a "block list" version
var clean = _.partial(_.omit, _, ['age']);

// and later
var result = clean(credentials);

Note that Lodash 5 will drop support for omit

A similar approach can be achieved without Lodash:

const transform = (obj, predicate) => {
  return Object.keys(obj).reduce((memo, key) => {
    if(predicate(obj[key], key)) {
      memo[key] = obj[key]
    }
    return memo
  }, {})
}

const omit = (obj, items) => transform(obj, (value, key) => !items.includes(key))

const pick = (obj, items) => transform(obj, (value, key) => items.includes(key))

// Partials
// Lazy clean
const cleanL = (obj) => omit(obj, ['age'])

// Guarded clean
const cleanG = (obj) => pick(obj, ['fname', 'lname'])


// "App"
const credentials = {
    fname:"xyz",
    lname:"abc",
    age:23
}

const omitted = omit(credentials, ['age'])
const picked = pick(credentials, ['age'])
const cleanedL = cleanL(credentials)
const cleanedG = cleanG(credentials)