CODEWITHSUNDEEP
javascriptlodash
alex
alex

Reputation: 7601

Why isn't omit() removing the undefined values after mapping?

I'm using the following Lodash chained utilities to map/flat and array and produce a new one while excluding the undefined valued.

const array = _(resp.data)
   .omit(_.isUndefined)
   .flatMap('building')
   .value()
console.log(array)

And this is the result:

enter image description here

As you can see the undefined values are still being included. Why is this?

EDIT:

resp.data looks like this

[
  { username: '', building: [ name: '' ] }
  { username: '', building: [ name: '' ] }
  // etc...
]

EDIT2:

Those undefined values are probably the empty building that come objects have.

Upvotes: 1

Views: 321

Answers (2)

ryeballar
ryeballar

Reputation: 30098

The extra undefined value should belong to a user in the resp.data where no building exist. All you have to do is to _.filter() all values that are undefined through _.identity() after the _.flatMap().

Note: Using _.omit should only be used against objects, using this in the context of an array (e.g. _.flatMap() which results in an array) would yield a result of an object wherein the index of each item is it's index in the array. You should use _.filter() instead.

var data = [
  { username: 'user1', building: [ { name: 'building1' } ] },
  { username: 'user2', building: [ { name: 'building2' } ] },
  { username: 'user3' }
];

var result = _(data)
  .flatMap('building')
  .filter(_.identity)
  .value();

document.write('<pre>' + JSON.stringify(result, 0, 4) + '</pre>');
<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.11.2/lodash.js"></script>

Upvotes: 2

Devank
Devank

Reputation: 159

Try this.

const array = _(resp.data)
.omit(_.isUndefined)
.flatMap('building')
.map()
.omit(_.isUndefined)
.value()

Upvotes: 1

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