group array of objects

Question

Hi guys i've question about how to group by key id value and do sum on ( key harga value and key qty value) below are the array of objects:

order: [
  {
    id: 4,
    idkatg: 2,
    kategori: 'minuman',
    nmprod: 'es mambo',
    harga: 8000,
    qty: 1
  },
  {
    id: 4,
    idkatg: 2,
    kategori: 'minuman',
    nmprod: 'es mambo',
    harga: 8000,
    qty: 1
  }
]

what i wan't to achieve is like this :

order:[
   {
     id: 4,
     idkatg: 2,
     kategori: 'minuman',
     nmprod: 'es mambo',
     harga: 14000,
     qty: 2
   }
]

is there any solution using lodash maybe ?

sorry guys but i have to wrap my head first with all these answer. i'll get back then — Denny Rachmadi
– Denny Rachmadi, Commented Sep 24, 2018 at 9:05

Nina Scholz · Accepted Answer · 2018-09-24 08:57:39Z

1

You could reduce the object and find the object with the same id, then update. Otherwise push the actual object to the result set.

If needed, you could take a sloppy copy with

r.push(Object.assign({}, o));

var order = [{ id: 4, idkatg: 2, kategori: 'minuman', nmprod: 'es mambo', harga: 8000, qty: 1 }, { id: 4, idkatg: 2, kategori: 'minuman', nmprod: 'es mambo', harga: 8000, qty: 1 }];

order = order.reduce((r, o) => {
   var temp = r.find(({ id }) => id === o.id);
   if (temp) {
       ['harga', 'qty'].forEach(k => temp[k] += o[k]);
   } else {
       r.push(o);
   }
   return r;
}, []);

console.log(order);

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

answered Sep 24, 2018 at 8:57

Nina Scholz

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1 Comment

Denny Rachmadi Over a year ago

I think your answer is much simple and elegant. Thanks

Rafal Wiliński · Accepted Answer · 2018-09-24 08:45:49Z

1

Try this:

const order = [
  {
    id: 4,
    idkatg: 2,
    kategori: 'minuman',
    nmprod: 'es mambo',
    harga: 8000,
    qty: 1
  },
  {
    id: 4,
    idkatg: 2,
    kategori: 'minuman',
    nmprod: 'es mambo',
    harga: 8000,
    qty: 1
  }
];

const newOrder = [];

for (const index in order) {
  const item = order[index];
  const itemInNewOrder = newOrder.filter(i => i.id === item.id)[0];

  if (itemInNewOrder) {
    itemInNewOrder.harga += item.harga;
  } else {
    newOrder.push(item);
  }
}

console.log(newOrder);

This question is similar to: Merge objects with the same id but sum values of the objects

answered Sep 24, 2018 at 8:45

Rafal Wiliński

2,4402 gold badges24 silver badges27 bronze badges

Comments

protoproto · Accepted Answer · 2018-09-24 09:00:01Z

You can use 2 pure for loops to set:

var order = [
  {
    id: 4,
    idkatg: 2,
    kategori: 'minuman',
    nmprod: 'es mambo',
    harga: 8000,
    qty: 1
  },
  {
    id: 4,
    idkatg: 2,
    kategori: 'minuman',
    nmprod: 'es mambo',
    harga: 8000,
    qty: 1
  },
  {
    id: 5,
    idkatg: 3,
    kategori: '5 minuman',
    nmprod: '5 es mambo',
    harga: 5000,
    qty: 3
  },
  {
    id: 5,
    idkatg: 3,
    kategori: '5 minuman',
    nmprod: '5 es mambo',
    harga: 4000,
    qty: 2
  },
  {
    id: 6,
    idkatg: 4,
    kategori: '6 minuman',
    nmprod: '6 es mambo',
    harga: 6000,
    qty: 2
  }
];

var result = [];
result.push(order[0]);
for (var i=1; i<order.length; i++){
  //compare object order[i] with order[0] ... order[n]
  var flagExist = false;
  for (var j=0; j<i; j++){
    if(order[j].id === order[i].id){
      flagExist = true;
      //set for object old, with new qty and harga
      order[j].qty = order[i].qty + order[j].qty;
      order[j].harga = order[i].harga + order[j].harga;
      break;
    }
  }
  if (flagExist == false)
    result.push(order[i]);
}
console.log(result);

Hassan Imam · Accepted Answer · 2018-09-24 09:01:16Z

1

You can use groupBy based on the id key and then using map reduce using sumBy & fromPairs operation.

let order = [ { id: 4, idkatg: 2, kategori: 'minuman', nmprod: 'es mambo', harga: 8000, qty: 1 }, { id: 4, idkatg: 2, kategori: 'minuman', nmprod: 'es mambo', harga: 8000, qty: 1 } ],
    result = _(order).groupBy('id').map((o,k) =>
      ({...o[0], ..._.fromPairs(_(['qty','harga']).map(k => [k,_.sumBy(o,k)]).value())})).value();
console.log(result);

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

answered Sep 24, 2018 at 9:01

Hassan Imam

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Comments

Koushik Chatterjee · Accepted Answer · 2018-09-24 10:52:48Z

Since you have tagged lodash this is as simple as (cleaner) this:

_(order).groupBy('id').map(a=>({...a[0], harga: _.sumBy(a, 'harga'), qty: _.sumBy(a, 'qty')})).value()

You can use reduce instead of 2 sumBy if you want to do the sum in a single iteration (however using lodash you are actually not looking for faster solution with less iterations anyway

let order = [
  {
    id: 4,
    idkatg: 2,
    kategori: 'minuman',
    nmprod: 'es mambo',
    harga: 8000,
    qty: 1
  },
  {
    id: 3,
    idkatg: 2,
    kategori: 'minuman',
    nmprod: 'es mambo',
    harga: 2000,
    qty: 1
  },
  {
    id: 4,
    idkatg: 2,
    kategori: 'minuman',
    nmprod: 'es mambo',
    harga: 8000,
    qty: 1
  },
  {
    id: 5,
    idkatg: 2,
    kategori: 'minuman',
    nmprod: 'es mambo',
    harga: 6000,
    qty: 1
  },
  {
    id: 5,
    idkatg: 2,
    kategori: 'minuman',
    nmprod: 'es mambo',
    harga: 9000,
    qty: 1
  }
];

let res =_(order).groupBy('id').map(a=>({...a[0], harga: _.sumBy(a, 'harga'), qty: _.sumBy(a, 'qty')})).value()

console.log(res);

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.11/lodash.min.js"></script>
https://stackoverflow.com/questions/52475365/group-array-of-objects/52475751#

There are Vanilla JS solution (and faster) for every lodash solution. But that's completely depend on you what you want, you are already using lodash or not. performance is really matter or cleanest code and maintainability and handling all the corner cases and some other factors.

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