merge duplicate objects in an array and combine sub array of each object

Question

I am trying to merge objects based off of Id, and merge each array that lives inside each account (object), but instead of merging the contents of accountList, the code overwrites the array, if there is a matching id.

I've made a new array and used the .find method to find matching objects based off there id, but stuck on how to merge the accountList together

const accounts = [
    {
    "Id": 103,
    "accountList": [
      {}
    ]
  },
  {
    "Id": 103,
    "accountList": [
      {
        "tokenId": "5aasdasdsdnjn3434nadd",
        "featureId": 2840
      }
    ]
  },
  {
    "Id": 112,
    "accountList": [
      {
        "tokenId": "5d30775bef4a722c38aefaaa",
        "featureId": 2877
      }
    ]
  },
    {
    "Id": 112,
    "accountList": [
      {
        "tokenId": "5d30775bef4a722c38aefccc",
        "featureId": 2856
      }
    ]
  }
]

let result = [];
accounts.forEach(account => {
  let match = result.find(r => r.Id === account.Id);
  // console.log(match)
  if(match) {
   Object.assign(match, account);
    //tried using spread operator instead of object assign, but didnt work
    //  match = {...match, ...account}
  } else {
    result.push(account);
  }
});

console.log( JSON.stringify(result, null, 2))

The result which i need is to merge the object based off their id, and merge the contents of the accountList together, like so:

[
  {
    "Id": 103,
    "accountList": [
      {
        "tokenId": "5aasdasdsdnjn3434nadd",
        "featureId": 2840
      }
    ]
  },
  {
    "Id": 112,
    "accountList": [
      {
        "tokenId": "5d30775bef4a722c38aefaaa",
        "featureId": 2877
      },
      {
        "tokenId": "5d30775bef4a722c38aefccc",
        "featureId": 2856
      }
    ]
  }
]

I updated my code, initially the empty object was also included. This has been fixed now. My bad. — Amardeep Bhowmick
– Amardeep Bhowmick, Commented Sep 4, 2019 at 10:55
Does this answer your question? Merge duplicate objects in array of objects — leonheess
– leonheess, Commented May 9, 2022 at 20:30

Yevhen Horbunkov · Accepted Answer · 2020-07-12 21:33:44Z

2

I think, reduce() would do the job:

const accounts = [{"Id":103,"accountList":[{}]},{"Id":103,"accountList":[{"tokenId":"5aasdasdsdnjn3434nadd","featureId":2840}]},{"Id":112,"accountList":[{"tokenId":"5d30775bef4a722c38aefaaa","featureId":2877}]},{"Id":112,"accountList":[{"tokenId":"5d30775bef4a722c38aefccc","featureId":2856}]}];

const result = [...accounts
        .reduce((r, o) => {
          const record = r.get(o.Id)||{}
          r.set(o.Id, {
            Id: o.Id,
            accountList: [
              ...(record.accountList||[]),
              ...o.accountList.filter(o => 
                Object.keys(o).length != 0)
            ]            
          })
          return r
        }, new Map())
        .values()]

console.log(result);

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

edited Jul 12, 2020 at 21:33

answered Aug 30, 2019 at 11:30

Yevhen Horbunkov

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2 Comments

Rakibul Islam Over a year ago

but if accountlist:{} it also pushed

Yevhen Horbunkov Over a year ago

@RakibulIslam : That doesn't seem to be the case according to OP's example.

Alexander Paschenko · Accepted Answer · 2019-08-30 11:40:30Z

1

You can try to use Array.concat:

    let result = [];
    accounts.forEach(account => {
      let match = result.find(r => r.Id === account.Id);
      // console.log(match)
      if(match) {
        match.accountList = match.accountList.concat(account.accountList);
      } else {
        result.push(account);
      }
    });

for (let res of result) {
  console.log('res.Id: ', res.Id, res.accountList)
}

// res.Id:  103 [ {}, { tokenId: '5aasdasdsdnjn3434nadd', featureId: 2840 } ]
// res.Id:  112 [ { tokenId: '5d30775bef4a722c38aefaaa', featureId: 2877 },
//   { tokenId: '5d30775bef4a722c38aefccc', featureId: 2856 } ]

edited Aug 30, 2019 at 11:40

answered Aug 30, 2019 at 11:32

Alexander Paschenko

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Comments

Amardeep Bhowmick · Accepted Answer · 2019-09-04 10:48:44Z

Using Array.prototype.reduce we can accumulate the results in the final result array.

In the reduce call back just find the matching object using Id and merge the accountList array and not the object as you were doing in your code.

const accounts=[{"Id":103,"accountList":[{}]},{"Id":103,"accountList":[{"tokenId":"5aasdasdsdnjn3434nadd","featureId":2840}]},{"Id":112,"accountList":[{"tokenId":"5d30775bef4a722c38aefaaa","featureId":2877}]},{"Id":112,"accountList":[{"tokenId":"5d30775bef4a722c38aefccc","featureId":2856}]}];

const result = accounts.reduce((acc, account) => {
     let match = acc.find(r => r.Id === account.Id);
     if(match) {
       match.accountList.push(...account.accountList); //push previous array
     } else {
       const act = { ...account }; 
       act.accountList = account.accountList.filter((obj) => Object.keys(obj).length);
       acc.push(act);
     }
     return acc;
}, []);
console.log(result);

shrys · Accepted Answer · 2019-08-30 11:33:02Z

0

I think you could use match.accountList.push(...account.accountList); instead of the object assign, spread operator can be used to push the element into the result item(match):

let accounts = [{ "Id": 103, "accountList": [{}] }, { "Id": 103, "accountList": [{ "tokenId": "5aasdasdsdnjn3434nadd", "featureId": 2840 }] }, { "Id": 112, "accountList": [{ "tokenId": "5d30775bef4a722c38aefaaa", "featureId": 2877 }] }, { "Id": 112, "accountList": [{ "tokenId": "5d30775bef4a722c38aefccc", "featureId": 2856 }] }];
let result = [];
accounts.forEach(account => {
  (match = result.find(r => r.Id === account.Id), match ? match.accountList.push(...account.accountList) : result.push(account))
});
console.log(result);

edited Aug 30, 2019 at 11:33

answered Aug 30, 2019 at 11:23

shrys

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Comments

Abito Prakash · Accepted Answer · 2019-08-30 14:04:06Z

0

const isNotEmptyObject = objc => Object.entries(objc).length > 0;

function mergeAccounts(accounts) {
    const uniqueAccounts = new Map();
    accounts.forEach(account => {
        if(uniqueAccounts.has(account.Id)) {
            let uniqueAccount = uniqueAccounts.get(account.Id);
            if(account.accountList && account.accountList.length > 0)
                uniqueAccount.accountList.push(...account.accountList);
                uniqueAccount.accountList = uniqueAccount.accountList.filter(isNotEmptyObject);
        } else {
            uniqueAccounts.set(account.Id, account);
        }
    });
  return Array.from(uniqueAccounts.values());
}

This will merge all the accounts having same ids. Hope this helps :)

edited Aug 30, 2019 at 14:04

answered Aug 30, 2019 at 13:12

Abito Prakash

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