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 } 

I am aware I can use

delete credentials.age 

but what if I have lots of unwanted properties? 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) 

Answer 2

Get a list of properties from model using _.keys(), and use _.pick() to extract the properties from credentials to a new object:

var model = {    fname:null,    lname:null };  var credentials = {     fname:"xyz",     lname:"abc",     age:23 };  var result = _.pick(credentials, _.keys(model));  console.log(result);

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.16.4/lodash.min.js"></script>

If you don't want to use Lodash, you can use Object.keys(), and Array.prototype.reduce():

var model = {    fname:null,    lname:null };  var credentials = {     fname:"xyz",     lname:"abc",     age:23 };  var result = Object.keys(model).reduce(function(obj, key) {   obj[key] = credentials[key];   return obj; }, {});  console.log(result);