Merge duplicate items in array of objects, concating nested arrays

Question

I have an array of objects that contains duplicates. I need to remove the duplicate while keeping the nested items objects.

To make it clear, this is what my source array looks like:

const src = [
  {
    id: '5f10b85e145d7163d818066e',
    name: 'Product 1',
    vendor: 'Vendor 1',
    instances: [
      {
        id: '5f10b8f6145d7163d8180672',
        operatingSystem: 'Microsoft Windows 2016',
        environment: 'Prod',
        version: '4.0',
        notes: '',
      },
    ],
  },
  {
    id: '5f10b856145d7163d818066d',
    name: 'Product 1',
    vendor: 'Vendor 2',
    instances: [
      {
        id: '5f10b8c5145d7163d8180671',
        operatingSystem: 'Microsoft Windows 2012R2',
        environment: 'Prod',
        version: '4.1',
        notes: '',
      },
    ],
  },
  {
    id: '5f10b85e145d7163d818066e',
    name: 'Product 1',
    vendor: 'Vendor 1',
    instances: [
      {
        id: '5f10b8f6145d7163d8180672',
        operatingSystem: 'Microsoft Windows 2016',
        environment: 'Prod',
        version: '4.0',
        notes: '',
      },
    ],
  },
];

Product 1 of Vendor 1 (with the same id) is duplicated. I need the instances of the duplicates, to be merged with the first item.

The result array should look like this:

const target = [
  {
    id: '5f10b85e145d7163d818066e',
    name: 'Product 1',
    vendor: 'Vendor 1',
    instances: [
      {
        id: '5f10b8f6145d7163d8180672',
        operatingSystem: 'Microsoft Windows 2016',
        environment: 'Prod',
        version: '4.0',
        notes: '',
      },
      {
        id: '5f10b8f6145d7163d8180672',
        operatingSystem: 'Microsoft Windows 2016',
        environment: 'Prod',
        version: '4.0',
        notes: '',
      },
    ],
  },
  {
    id: '5f10b856145d7163d818066d',
    name: 'Product 1',
    vendor: 'Vendor 2',
    instances: [
      {
        id: '5f10b8c5145d7163d8180671',
        operatingSystem: 'Microsoft Windows 2012R2',
        environment: 'Prod',
        version: '4.1',
        notes: '',
      },
    ],
  },
];

Sven.hig · Accepted Answer · 2020-07-19 21:57:30Z

1

You could use reduce and then wrap the response with Object.values to remove the keys added by reduce

const src = [ { id: '5f10b85e145d7163d818066e', name: 'Product 1', vendor: 'Vendor 1', instances: [ { id: '5f10b8f6145d7163d8180672', operatingSystem: 'Microsoft Windows 2016', environment: 'Prod', version: '4.0', notes: '', }, ], }, { id: '5f10b856145d7163d818066d', name: 'Product 1', vendor: 'Vendor 2', instances: [ { id: '5f10b8c5145d7163d8180671', operatingSystem: 'Microsoft Windows 2012R2', environment: 'Prod', version: '4.1', notes: '', }, ], }, { id: '5f10b85e145d7163d818066e', name: 'Product 1', vendor: 'Vendor 1', instances: [ { id: '5f10b8f6145d7163d8180672', operatingSystem: 'Microsoft Windows 2016', environment: 'Prod', version: '4.0', notes: '', }, ], }, ];
var res=src.reduce((a,c)=>{
  if (!a[c.id]) a[c.id]= {...a[c.id],...c}
  else {
    a[c.id].instances.push(c.instances)
    a[c.id].instances=[].concat(...a[c.id].instances);
  }
return a
},{})
console.log(Object.values(res))

edited Jul 19, 2020 at 21:57

answered Jul 19, 2020 at 21:48

Sven.hig

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5 Comments

Yevhen Horbunkov Over a year ago

Map based solutions (e.g. mine) will work muuuch faster

Sven.hig Over a year ago

@YevgenGorbunkov do you have any resources or something to prove that ?

Yevhen Horbunkov Over a year ago

Would you bother to follow the link in the first comment?

Sven.hig Over a year ago

would you bother provide a resource because the link you provided doesn't prove anything

Yevhen Horbunkov Over a year ago

If you don't trust my benchmark you may do yours. Proving anything to the person refusing to believe one's own eyes see, doesn't make much sense.

Lino Contreras · Accepted Answer · 2020-07-19 21:23:15Z

1

You could use a Map to keep the ids and the first occurrence of an object.

Then using the filter function check if an id has already been added.

const src = [
    { id: 'foo', name: 'Product 1', instances: [{ key: 'value a' }] },
    { id: 'bar', name: 'Product 2', instances: [{ key: 'value b' }] },
    { id: 'foo', name: 'Product 1', instances: [{ key: 'value c' }] }
];

const unique = new Map();

const target = src.filter((product) => {
    if (unique.has(product.id)) {
        unique.get(product.id).instances.push(...product.instances);
        return false;
    }

    unique.set(product.id, product);
    return true;
});

console.log(target);

edited Jul 19, 2020 at 21:23

answered Jul 19, 2020 at 21:04

Lino Contreras

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Comments

EvanMorrison · Accepted Answer · 2020-07-19 21:28:33Z

There's a number of ways to go about it. Here's one.

const src = [{
    id: '5f10b85e145d7163d818066e',
    name: 'Product 1',
    vendor: 'Vendor 1',
    instances: [{
      id: '5f10b8f6145d7163d8180672',
      operatingSystem: 'Microsoft Windows 2016',
      environment: 'Prod',
      version: '4.0',
      notes: '',
    }, ],
  },
  {
    id: '5f10b856145d7163d818066d',
    name: 'Product 1',
    vendor: 'Vendor 2',
    instances: [{
      id: '5f10b8c5145d7163d8180671',
      operatingSystem: 'Microsoft Windows 2012R2',
      environment: 'Prod',
      version: '4.1',
      notes: '',
    }, ],
  },
  {
    id: '5f10b85e145d7163d818066e',
    name: 'Product 1',
    vendor: 'Vendor 1',
    instances: [{
      id: '5f10b8f6145d7163d8180672',
      operatingSystem: 'Microsoft Windows 2016',
      environment: 'Prod',
      version: '4.0',
      notes: '',
    }, ],
  },
];

function deDupe(input) {
  let result = [];
  let productMap = {};
  input.forEach((product, idx) => {
    if (!productMap[product.id]) {
      productMap[product.id] = input[idx];
    } else {
      productMap[product.id].instances.push(...input[idx].instances);
    }
  });

  return Object.values(productMap)
}

console.log(deDupe(src));

Yevhen Horbunkov · Accepted Answer · 2020-07-19 22:23:28Z

You may use Array.prototype.reduce() to traverse source array and build up the Map where id is used as a key, so once you get duplicating id, you push instances of the current object into existing entry, or set new entry, otherwise. When Map is ready, you simply extract its values with Map.prototype.values():

const src = [{id:'5f10b85e145d7163d818066e',name:'Product 1',vendor:'Vendor 1',instances:[{id:'5f10b8f6145d7163d8180672',operatingSystem:'Microsoft Windows 2016',environment:'Prod',version:'4.0',notes:'',},],},{id:'5f10b856145d7163d818066d',name:'Product 1',vendor:'Vendor 2',instances:[{id:'5f10b8c5145d7163d8180671',operatingSystem:'Microsoft Windows 2012R2',environment:'Prod',version:'4.1',notes:'',},],},{id:'5f10b85e145d7163d818066e',name:'Product 1',vendor:'Vendor 1',instances:[{id:'5f10b8f6145d7163d8180672',operatingSystem:'Microsoft Windows 2016',environment:'Prod',version:'4.0',notes:'',},],},],

      result = [...src
        .reduce((r, o) => {
          const dupe = r.get(o.id)
          dupe ? 
          dupe.instances.push(...o.instances) : 
          r.set(o.id, o)
          return r
        }, new Map())
        .values()
      ]
      
console.log(result)

.as-console-wrapper{min-height:100%;}

greg-tumolo · Accepted Answer · 2020-07-22 04:22:07Z

0

Use a map from id to objects like:

const map = {}
...
// Given object:
if (object.id in map) {
  const object_master = map[object.id]
  object_master.instances.push(...object.instances)
} else map[object.id] = object

edited Jul 22, 2020 at 4:22

answered Jul 19, 2020 at 21:09

greg-tumolo

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