groupBy array of objects with underscore.js

Question

I have a array (order) of objects (products): , I want to group and count all these products by id:

var order = [
{ product_id: 70, product_price: 9, product_color: "ccc"},
{ product_id: 70, product_price: 9, product_color: "ccc"},
{ product_id: 71, product_price: 10, product_color: "fff" } ];

with Underscore.js:

var groups = _.countBy(order, function(value){
    return value.product_id + "#" + value.product_price + "#" + value.product_color;
})
//--> Object {70#ccc#9: 2, 71#fff#10: 1}

So it works… but now, how can I return theses values into an array like this, so I can work with this as a new array of objects?

 [
    { product_id: 70, product_price: 9, product_color: "ccc", count: 2},
    { product_id: 70, product_price: 9, product_color: "fff", count: 1}
 ];

Gruff Bunny · Accepted Answer · 2016-11-10 13:34:21Z

1

Instead of countBy you could use groupBy and then map across the groups to add the count:

var groups = _.groupBy(order, function(value){
    return value.product_id + "#" + value.product_price + "#" + value.product_color;
})

groups = _.map(groups, function(group){
    return _.extend(group[0], {count: group.length});
});

answered Nov 10, 2016 at 13:34

Gruff Bunny

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1 Comment

shlagwuk Over a year ago

Well, that was easy :-) Thanks!

marzelin · Accepted Answer · 2016-11-10 13:42:31Z

0

You can use reduce to recreate the original array.

var countedById = [
    { product_id: 70, product_price: 9, product_color: "ccc", count: 2},
    { product_id: 70, product_price: 9, product_color: "fff", count: 1}
 ];

var original = countedById.reduce((acc, cur) => {
  for (var i = 0; i < cur.count; i++) {
    var original = {
      product_id: cur.product_id,
      product_price: cur.product_price,
      product_color: cur.product_color
    }
    acc.push(original);
  }
  return acc;
  }, []);

document.write(JSON.stringify(original))

answered Nov 10, 2016 at 13:42

marzelin

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