Lodash cloneDeepWith to omit undefined

Question

I wrote a customozer function to omit the undefined values of the object with cloneDeepWith. However on the immutable return, it is not digging in recursively. Here is my code:

import { cloneDeepWith, pickBy, omit } from 'lodash';

const obj = {
  a0: true,
  b0: true,
  c0: undefined,
  obj1: {
    a1: true,
    b1: true,
    c1: undefined
  }
};

cloneDeepWith(obj, value => {
    const objWithUndefinedValue = pickBy(obj, (value) => value === undefined);
    const keysWithUndefinedValue = Object.keys(objWithUndefinedValue);
    return omit(obj, keysWithUndefinedValue);
});

However it doesn't recurse after the first return. Is it possible to accomplish this with lodash stock functionality?

Answer 1

This can be solved by using recursively lodash transform method via:

const obj = { a0: true, b0: true, c0: undefined, obj1: { a1: true, b1: true, c1: undefined } };

const cloneMe = (obj) => _.transform(obj, (r, v, k) => 
  _.isUndefined(v) ? null : _.isObject(v) ? r[k] = cloneMe(v) : r[k] = v, {})

console.log(cloneMe(obj))

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.11/lodash.js"></script>

You could also do this in ES6 only via Object.entries & reduce:

const obj = { a0: true, b0: true, c0: undefined, obj1: { a1: true, b1: true, c1: undefined } };

const cloneMe = (obj) => {
   return Object.entries(obj).filter(([k,v]) => 
      v != undefined).reduce((r,[k,v]) => {
        r[k] = (v instanceof Object) ? cloneMe(v) : v
        return r
   },{})
}

console.log(cloneMe(obj))

You can additionally extend the check for object if instance of Object is not sufficient etc.

Answer 2

There's another alternative using DeepDash, which is a standalone, complementary library that offers recursive versions of Lodash functions.

Once DeepDash has been mixed in with Lodash (deepdash(_)), you can write a prune function like this:

const prune = obj => _.filterDeep(obj, (v) => !_.isUndefined(v))