CODEWITHSUNDEEP
sortinglodash
Alex D
Alex D

Reputation: 753

Lodash sortedby object list is stuck in _wrapper_

I am experimenting with lodash sorting. I got the lodash to sort the object list although the sorted results are stuck in wrapper. If I use .value(), then I get unsorted keys output.

var testData = {c:1,b:2,a:3}

var sortedKeys = _(testData).keys().sortBy(key => {return testData.key});
console.log(sortedKeys);

will produce:

LodashWrapper {__wrapped__: {…}, __actions__: Array(2), __chain__: false, __index__: 0, __values__: undefined}
__actions__:(2) [{…}, {…}]
__chain__:false
__index__:0
__values__:undefined
__wrapped__:
            a:3
            b:2
            c:1
__proto__:Object
__proto__:lodash

What is it that I am missing in order to get sorted object list out of lodash wrapper.

Upvotes: 2

Views: 2312

Answers (2)

Akrion
Akrion

Reputation: 18525

There are few things that are happening here which I think are important to note:

First you are starting your sorting statement with the short notation for the lodash _.chain method which allows the results of one operation to flow into the next one. This is similar to how _.flow works in lodash/fp.

Chaining requires the last operation in the chain to end with values() in order to get your actual result from the lodash wrapper. So if you did:

_(testData).keys().sortBy(key => {return testData.key}).values(); // OR
_.chian(testData).keys().sortBy(key => {return testData.key}).values();

You would get some results.

Second issue is that in your flow you get the keys of the objects but then you are not actually sorting by them. To do this you need something like this:

var testData = {c:1, b:2, a:3}

console.log(_.chain(testData).keys().sortBy().value());
<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.10/lodash.min.js"></script>

The difference here is in the sort function where you already have the keys as `[ 'c', 'b', 'a' ] so you just need to sort them. They are not objects anymore but simply strings.

Hope this helps.

Upvotes: 0

kyle
kyle

Reputation: 691

When you do testData.key, I'm pretty confident that you actually mean to be doing testData[key].

That alone allows the method to work properly i.e. return an array of Object keys sorted by values. Note that you still have to call .value() if you'd like to unwrap the lodash object.

If there's something else you're expecting, please clarify.

const testData = {c:1,b:2,a:0}

const sortedKeys = _(testData).keys().sortBy(key => {return testData[key]})
/* can do without the return like the below as well */
// const sortedKeys = _(testData).keys().sortBy(key => testData[key])

console.log(sortedKeys.value())
// produces ['a','c','b']

If you want the key and value pair, try the below.

_(obj).toPairs().sortBy(0).value()

Upvotes: 1

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