How to merge Array of Objects based on the same value?

Question

I have this array of Objects:

var array = [{
    country: "Austria",
    name: "2019-01-04T23:00:00.000Z",
    value: "1"
  },
  {
    country: "Austria",
    name: "2019-01-11T23:00:00.000Z",
    value: "3"
  },
  {
    country: "Austria",
    name: "2019-01-18T23:00:00.000Z",
    value: "1"
  }
]

I want manipulate this to achieve this result:

var array = [{
  country: "Austria",
  series: [{
      name: "2019-01-04T23:00:00.000Z",
      value: "1"
    },
    {
      name: "2019-01-11T23:00:00.000Z",
      value: "3"
    },
    {
      name: "2019-01-18T23:00:00.000Z",
      value: "1"
    }
  ]
}]

I read many questions but none helped me.

adiga · Accepted Answer · 2019-06-04 20:02:10Z

1

You could loop thorugh the array. Use destructuring to get country and rest of the properties separately. Add each unique country to group object as key and push the rest object to the series array. Then use Object.values() to get the values as an array

const array=[{country:"Austria",name:"2019-01-04T23:00:00.000Z",value:"1"},{country:"Austria",name:"2019-01-11T23:00:00.000Z",value:"3"},{country:"Austria",name:"2019-01-18T23:00:00.000Z",value:"1"}];

const group = {};

array.forEach(({ country, ...rest }) => {
  group[country] = group[country] || { country, series: [] };
  group[country].series.push(rest)
})

console.log(Object.values(group))

edited Jun 4, 2019 at 20:02

answered Jun 4, 2019 at 19:54

adiga

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1 Comment

faienz93 Over a year ago

It works. I decide to vote on this answer because I think it's a compact form that makes it easy to understand :)

zhulien · Accepted Answer · 2019-06-04 19:36:29Z

1

This should do:

var map = {};

for(var entity of array) {
    if(!map[entity.country]) {
        map[entity.country] = {
            country: entity.country,
            series: [
                {
                    name: entity.name,
                    value: entity.value
                }
            ]
        };
    }
    else {
        map[entity.country].series.push({
            name: entity.name,
            value: entity.value            
        });
    }
}

var mappedArray = Object.values(map);

answered Jun 4, 2019 at 19:36

zhulien

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Comments

Goran · Accepted Answer · 2019-06-04 19:44:04Z

1

Here is functional solution without for loops and mutable variables:

const result = array.reduce((carry, item) => {
    if (!carry.includes(item.country)) {
        carry.push(item.country);
    }
    return carry;
}, []).map(country => {
    return {
        country: country,
        series: array.filter(item => item.country === country).map(item => {
            return {
                name: item.name,
                value: item.value
            };
        })
    };

answered Jun 4, 2019 at 19:44

Goran

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Comments

German Burgardt · Accepted Answer · 2019-06-04 19:28:33Z

0

You can do something like:

const result = array
    .map(
        c => ({
            country: c.country,
            series: array
                .filter(d => d.country === c.country)
                .map(
                    d => ({
                        name: d.name,
                        value: d.value
                    })
                )
        })
    )

answered Jun 4, 2019 at 19:28

German Burgardt

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