Merge array of an object based on a common field

Question

I have an object that looks like as follows:

[
    {
        "Net_Amount": 499,
        "Date": "2022-01-09T18:30:00.000Z",
        "Scheme_Name": "CUSTOMERWINBACKJCA01",
        "Month": "Jan"
    },
    {
        "Net_Amount": 902,
        "Date": "2022-01-09T18:30:00.000Z",
        "Scheme_Name": "CUSTOMERWINBACKJCA02",
        "Month": "Jan"
    },
    {
        "Net_Amount": 1860,
        "Date": "2022-10-01T18:30:00.000Z",
        "Scheme_Name": "CUSTOMERCONNECTJCA",
        "Month": "Oct"
    },
    {
        "Net_Amount": 1889,
        "Date": "2022-11-01T18:30:00.000Z",
        "Scheme_Name": "CUSTOMERCONNECTJCA",
        "Month": "Nov"
    }
]

Now, if you will look carefully, I have a common field Month in the objects and I want merge the objects based on this common field only. How I want my object to be formatted is as :

[
    {
        "Month": "Jan",
        "varData":  [{
            "Net_Amount": 499,
            "Date": "2022-01-09T18:30:00.000Z",
            "Scheme_Name": "CUSTOMERWINBACKJCA01"
        },
        {
            "Net_Amount": 902,
            "Date": "2022-01-09T18:30:00.000Z",
            "Scheme_Name": "CUSTOMERWINBACKJCA02"
        }]
    },
    {
        "Month": "Oct",
        "varData":  [{
            "Net_Amount": 1860,
            "Date": "2022-10-01T18:30:00.000Z",
            "Scheme_Name": "CUSTOMERCONNECTJCA"
        }]
    },
    {
        "Month": "Nov",
        "varData":  [{
            "Net_Amount": 1889,
            "Date": "2022-11-01T18:30:00.000Z",
            "Scheme_Name": "CUSTOMERCONNECTJCA"
        }]
    }
]

I can do it by iterating over the array and checking if month is same, then pushing the other key and its value of object in the varData but I want to know if there is any shortcut or inbuilt function which I can use to achieve my purpose.

zavg · Accepted Answer · 2023-02-13 16:33:53Z

2

I don't think that there is some better built-in solution then iterating the array.

But if you use month names as keys then the code could be quite straightforward (the output is not exactly the same but quite similarly structured).

const result = {}
for (const entry of list) {
  if (!result[entry.Month]) {
     result[entry.Month] = []
  }
  result[entry.Month].push(entry)
}

See jsfiddle.

If you need the output that is exactly specified in the question then you can use the following code:

let result = {}
for (const entry of list) {
  const month = entry.Month
  if (!result[month]) {
     result[month] = {
      "Month":   month,
      "varData": []
     }
  }
  delete entry.Month
  result[month].varData.push(entry)
}
result = Object.values(result)

See jsfiddle

edited Feb 13, 2023 at 16:33

answered Feb 13, 2023 at 14:03

zavg

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2 Comments

Anil kumar Over a year ago

Output result doesn't match with required result.

zavg Over a year ago

@Anilkumar I have added the 2nd version with an exact output.

Andrew Parks · Accepted Answer · 2023-02-13 14:04:14Z

1

const data = [{"Net_Amount":499,"Date":"2022-01-09T18:30:00.000Z","Scheme_Name":"CUSTOMERWINBACKJCA01","Month":"Jan"},{"Net_Amount":902,"Date":"2022-01-09T18:30:00.000Z","Scheme_Name":"CUSTOMERWINBACKJCA02","Month":"Jan"},{"Net_Amount":1860,"Date":"2022-10-01T18:30:00.000Z","Scheme_Name":"CUSTOMERCONNECTJCA","Month":"Oct"},{"Net_Amount":1889,"Date":"2022-11-01T18:30:00.000Z","Scheme_Name":"CUSTOMERCONNECTJCA","Month":"Nov"}]

console.log([...new Set(data.map(i=>i.Month))].map(Month=>
  ({Month, varData: data.filter(({Month:m})=>m===Month).map(({Month,...o})=>o)})))

answered Feb 13, 2023 at 14:04

Andrew Parks

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Comments

Anil kumar · Accepted Answer · 2023-02-13 14:15:23Z

const dataArr = [
    {
        Net_Amount: 499,
        Date: "2022-01-09T18:30:00.000Z",
        Scheme_Name: "CUSTOMERWINBACKJCA01",
        Month: "Jan",
    },
    {
        Net_Amount: 902,
        Date: "2022-01-09T18:30:00.000Z",
        Scheme_Name: "CUSTOMERWINBACKJCA02",
        Month: "Jan",
    },
    {
        Net_Amount: 1860,
        Date: "2022-10-01T18:30:00.000Z",
        Scheme_Name: "CUSTOMERCONNECTJCA",
        Month: "Oct",
    },
    {
        Net_Amount: 1889,
        Date: "2022-11-01T18:30:00.000Z",
        Scheme_Name: "CUSTOMERCONNECTJCA",
        Month: "Nov",
    },
];

const outputObj = dataArr.reduce((acc, crt) => {
    acc[crt.Month] ??= [];
    acc[crt.Month].push(crt);
    return acc;
}, {});


const outputArr = Object.values(outputObj).map((item) => ({ Month: item[0].Month, varData: item }));

console.log(outputArr);

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