how to find duplicates in array and merge nested data

Question

I have an object array with duplicates. The data at the root level of the objects are identical, but the nested array of objects are not. That is what I need to merge before running a lodash uniqBy or whatever function to remove the duplicates.

This is the object array with duplicates.

    [
    {
        "id": "66E175A2-A29F-4F1A-AD81-2422B1EB00F6",
        "name": "College Park / Brookhaven",
        "mktId": 0,
        "status": "Unknown",
        "code": "197D6",
        "ownershipType": null,
        "series": [
            {
                "id": "80004F2E-E3C8-4B6A-BCCC-81259AEAF22D",
                "name": "01",
                "productType": "Detached",
                "productClass": "Single Family",
                "salesStartDate": null,
                "modelOpenDate": null
            }
        ]
    },
    {
        "id": "E053E656-4D14-4F2A-AD70-A37F65195CD1",
        "name": "College Park / Hampshire",
        "mktId": 0,
        "status": "Unknown",
        "code": "316D6",
        "ownershipType": null,
        "series": [
            {
                "id": "46830FBD-CD68-4D4C-A095-FB9C3D93D01A",
                "name": "02,03",
                "productType": "Detached",
                "productClass": "Single Family",
                "salesStartDate": null,
                "modelOpenDate": null
            }
        ]
    },
    {
        "id": "E053E656-4D14-4F2A-AD70-A37F65195CD1",
        "name": "College Park / Hampshire",
        "mktId": 0,
        "status": "Unknown",
        "code": "316D6",
        "ownershipType": null,
        "series": [
            {
                "id": "1BC31692-AAB8-4A00-9D8D-9B8CF7E426E0",
                "name": "01",
                "productType": "Detached",
                "productClass": "Single Family",
                "salesStartDate": null,
                "modelOpenDate": null
            }
        ]
    },
    {
        "id": "34F7C7AF-3D1B-4EE7-8271-C99294169C01",
        "name": "College Park / Hillsdale",
        "mktId": 0,
        "status": "Unknown",
        "code": "295D6",
        "ownershipType": null,
        "series": [
            {
                "id": "807144A1-26ED-4657-9775-7DF7563107D3",
                "name": "02",
                "productType": "Detached",
                "productClass": "Single Family",
                "salesStartDate": null,
                "modelOpenDate": null
            }
        ]
    }
]

College Park / Hampshire is duplicated in this example. I need to find the 2 duplicates and return this expected result..

   [
    {
        "id": "66E175A2-A29F-4F1A-AD81-2422B1EB00F6",
        "name": "College Park / Brookhaven",
        "mktId": 0,
        "status": "Unknown",
        "code": "197D6",
        "ownershipType": null,
        "series": [
            {
                "id": "80004F2E-E3C8-4B6A-BCCC-81259AEAF22D",
                "name": "01",
                "productType": "Detached",
                "productClass": "Single Family",
                "salesStartDate": null,
                "modelOpenDate": null
            }
        ]
    },
    {
        "id": "E053E656-4D14-4F2A-AD70-A37F65195CD1",
        "name": "College Park / Hampshire",
        "mktId": 0,
        "status": "Unknown",
        "code": "316D6",
        "ownershipType": null,
        "series": [
            {
                "id": "46830FBD-CD68-4D4C-A095-FB9C3D93D01A",
                "name": "02,03",
                "productType": "Detached",
                "productClass": "Single Family",
                "salesStartDate": null,
                "modelOpenDate": null
            },
            {
                "id": "1BC31692-AAB8-4A00-9D8D-9B8CF7E426E0",
                "name": "01",
                "productType": "Detached",
                "productClass": "Single Family",
                "salesStartDate": null,
                "modelOpenDate": null
            }
        ]
    },
    {
        "id": "34F7C7AF-3D1B-4EE7-8271-C99294169C01",
        "name": "College Park / Hillsdale",
        "mktId": 0,
        "status": "Unknown",
        "code": "295D6",
        "ownershipType": null,
        "series": [
            {
                "id": "807144A1-26ED-4657-9775-7DF7563107D3",
                "name": "02",
                "productType": "Detached",
                "productClass": "Single Family",
                "salesStartDate": null,
                "modelOpenDate": null
            }
        ]
    }
]

vanilla javascript or lodash is fine.

Possible duplicate of Group array of object nesting some of the keys with specific names — Heretic Monkey
– Heretic Monkey, Commented Mar 14, 2018 at 19:07

felixmosh · Accepted Answer · 2018-03-14 19:14:06Z

I've created HashMap using reduce, in that hashMap, the key is the name of the item, the value is the item itself.

const data = [{
    "id": "66E175A2-A29F-4F1A-AD81-2422B1EB00F6",
    "name": "College Park / Brookhaven",
    "mktId": 0,
    "status": "Unknown",
    "code": "197D6",
    "ownershipType": null,
    "series": [{
      "id": "80004F2E-E3C8-4B6A-BCCC-81259AEAF22D",
      "name": "01",
      "productType": "Detached",
      "productClass": "Single Family",
      "salesStartDate": null,
      "modelOpenDate": null
    }]
  },
  {
    "id": "E053E656-4D14-4F2A-AD70-A37F65195CD1",
    "name": "College Park / Hampshire",
    "mktId": 0,
    "status": "Unknown",
    "code": "316D6",
    "ownershipType": null,
    "series": [{
      "id": "46830FBD-CD68-4D4C-A095-FB9C3D93D01A",
      "name": "02,03",
      "productType": "Detached",
      "productClass": "Single Family",
      "salesStartDate": null,
      "modelOpenDate": null
    }]
  },
  {
    "id": "E053E656-4D14-4F2A-AD70-A37F65195CD1",
    "name": "College Park / Hampshire",
    "mktId": 0,
    "status": "Unknown",
    "code": "316D6",
    "ownershipType": null,
    "series": [{
      "id": "1BC31692-AAB8-4A00-9D8D-9B8CF7E426E0",
      "name": "01",
      "productType": "Detached",
      "productClass": "Single Family",
      "salesStartDate": null,
      "modelOpenDate": null
    }]
  },
  {
    "id": "34F7C7AF-3D1B-4EE7-8271-C99294169C01",
    "name": "College Park / Hillsdale",
    "mktId": 0,
    "status": "Unknown",
    "code": "295D6",
    "ownershipType": null,
    "series": [{
      "id": "807144A1-26ED-4657-9775-7DF7563107D3",
      "name": "02",
      "productType": "Detached",
      "productClass": "Single Family",
      "salesStartDate": null,
      "modelOpenDate": null
    }]
  }
];

const hashMap = data.reduce((hash, item) => {
  const key = item.name;
  if (hash.hasOwnProperty(key)) {
    hash[key].series = hash[key].series.concat(item.series);
  } else {
    hash[key] = item;
  }
  return hash;
}, {});

const result = Object.keys(hashMap).map((key) => hashMap[key]);

console.log(result);

Jonas Wilms · Accepted Answer · 2018-03-14 19:04:03Z

0

Just set up a hashmap for the ids and a resulting array:

const hash = {}, result = [];

Then iterate over the array:

 for(const el of array){
   const { id, series } = el;

Now we can check if the id already appears in the hash, and if so just add the series:

   if(hash[id]){
     hash[id].series.push(...series);
   } else {

If the id did not appear yet, we need to add the object to our result and to the hashtable:

     result.push(hash[id] = el)
  }
}

And thats already it :)

answered Mar 14, 2018 at 19:04

Jonas Wilms

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