Filter Objects of Array of Objects using lodash

Question

I have a Objects of an array of objects as given below. I am trying to filter out each object within the array where is quantity is greater than 0 and drop it in a new variable. So via lodash I tried to use _.filter within _.(myArr).forEach. But this always returns an empty array. The console.log within _.filter shows quantity as it is but it doesn't return any value based on the condition. Am I using it in a proper way here or is there any other way I can use this to filter out?

var data = [
  [{
    "aid": "1",
    "desc": "Desc 1",
    "name": "Name 1",
    "quantity": 1
  }, {
    "aid": "2",
    "desc": "Desc 2",
    "name": "Name 2",
    "quantity": 1
  }, {
    "aid": "3",
    "desc": "Desc 3",
    "name": "Name 3",
    "quantity": 0
  }],
  [{
    "aid": "4",
    "desc": "Desc 4",
    "name": "Name 4",
    "quantity": 0
  }, {
    "aid": "5",
    "desc": "Desc 5",
    "name": "Name 5",
    "quantity": 1
  }],
  [{
    "aid": "6",
    "desc": "Desc 6",
    "name": "Name 6",
    "quantity": 0
  }, {
    "aid": "7",
    "desc": "Desc 7",
    "name": "Name 7",
    "quantity": 0
  }]
];

var filtered;
_(data).forEach((d) => {
  filtered = _.filter(d, (o) => {
    return o.quantity > 0;
  });
});

console.log(filtered);

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.14.0/lodash.min.js"></script>

trincot · Accepted Answer · 2018-03-14 07:32:09Z

2

You are overwriting filtered in each iteration, so its value will represent only what happened in the last iteration of the forEach loop.

You should instead accumulate the individual results into an array, for instance with push and the spread syntax:

var filtered = [];

... and in the loop:

    filtered.push(..._.filter(d, (o) => o.quantity > 0);

Note that you can do this in vanilla JavaScript, using array methods like reduce and filter:

var data = [ [{ "aid": "1", "desc": "Desc 1", "name": "Name 1", "quantity": 1 }, { "aid": "2", "desc": "Desc 2", "name": "Name 2", "quantity": 1 }, { "aid": "3", "desc": "Desc 3", "name": "Name 3", "quantity": 0 }], [{ "aid": "4", "desc": "Desc 4", "name": "Name 4", "quantity": 0 }, { "aid": "5", "desc": "Desc 5", "name": "Name 5", "quantity": 1 }], [{ "aid": "6", "desc": "Desc 6", "name": "Name 6", "quantity": 0 }, { "aid": "7", "desc": "Desc 7", "name": "Name 7", "quantity": 0}]];

var filtered = data.reduce( 
    (filtered, d) => filtered.concat(d.filter( o => o.quantity > 0 )),
    []
);

console.log(filtered);

.as-console-wrapper { max-height: 100% !important; top: 0; }

edited Mar 14, 2018 at 7:32

answered Mar 14, 2018 at 5:41

trincot

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4 Comments

Guruprasad J Rao Over a year ago

Awesome.. Thank you so much for the detailed response.. :)

Guruprasad J Rao Over a year ago

Which of the above approaches you suggest as the best to adapt? :)

trincot Over a year ago

Since JavaScript ES5 and certainly ES6 there is less reason to use a library as lodash, but if you need it for other purposes which cannot be written that well in ES6, then of course you can use it throughout.

Guruprasad J Rao Over a year ago

Well yeah, I am using lodash in most of the areas of the project, so I would be going with the same.. Thank you so much once again.. :)

guijob · Accepted Answer · 2018-03-14 06:56:51Z

2

using native js:

let filtered = data.reduce((a, e) => a.concat(e)).filter(x => x.quantity > 0);

edited Mar 14, 2018 at 6:56

answered Mar 14, 2018 at 5:44

guijob

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3 Comments

trincot Over a year ago

There is more data than only in data[0].

RaR Over a year ago

data.reduce((a, e) => a.concat(e)), [...data.reduce((a, e) => a.concat(e))], [...data.reduce((a, e) => a.concat(e))].reduce((a, e) => a.concat(e), []) -> There three will produce the same output, isn't it? Why don't we directly write data.reduce((a, e) => a.concat(e)) .filter(x => x.quantity > 0);. Am I missing something?

guijob Over a year ago

@RaR you are absolutely right. I've got lost mixing approaches. I'm very glad you'd notice it, cheers!

gurvinder372 · Accepted Answer · 2018-03-14 06:24:18Z

1

Or alternatively you can use reduce

var output = data.reduce( 
    ( acc, c ) => acc.concat( c.filter( 
           s => s.quantity > 0 ) )  //filter out quantities > 0
    ,[]); //initialize accumulator to []

Demo

var data = [
  [{
    "aid": "1",
    "desc": "Desc 1",
    "name": "Name 1",
    "quantity": 1
  }, {
    "aid": "2",
    "desc": "Desc 2",
    "name": "Name 2",
    "quantity": 1
  }, {
    "aid": "3",
    "desc": "Desc 3",
    "name": "Name 3",
    "quantity": 0
  }],
  [{
    "aid": "4",
    "desc": "Desc 4",
    "name": "Name 4",
    "quantity": 0
  }, {
    "aid": "5",
    "desc": "Desc 5",
    "name": "Name 5",
    "quantity": 1
  }],
  [{
    "aid": "6",
    "desc": "Desc 6",
    "name": "Name 6",
    "quantity": 0
  }, {
    "aid": "7",
    "desc": "Desc 7",
    "name": "Name 7",
    "quantity": 0
  }]
];
var output = data.reduce( ( acc, c ) => acc.concat( c.filter( s => s.quantity > 0 ) )  ,[]); 
console.log(output);

edited Mar 14, 2018 at 6:24

answered Mar 14, 2018 at 5:47

gurvinder372

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4 Comments

Guruprasad J Rao Over a year ago

That errors out.. c.filter is not a function.. :(

gurvinder372 Over a year ago

Ohh, let me share a demo with you. C is an array so it must have a filter method.

gurvinder372 Over a year ago

@GuruprasadRao Please check the updates, I have attached a demo now.

Guruprasad J Rao Over a year ago

Thank you so much bro. I would like to go with the accepted answer. But nonetheless, this will be useful somewhere in future.. :)

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