Creating array of objects based on another array of objects

Question

Trying creating array of objects based on another array of objects. Decided to use flatmap and then reduce, but the problem is when I have more than one object in result array - I can not collected several statuses in one object. Have added what i tried and what is result I am trying to achieve.

What I have

const data = [
    {
        "timestamp": "2021-08-31T15:29:18Z",
        "result": [
            {
                "label": "Not Covered",
                "value": 132
            }
        ]
    },
    {
        "timestamp": "2021-09-30T15:29:18Z",
        "result": [
            {
                "label": "Not Covered",
                "value": 135
            }
        ]
    },
    {
        "timestamp": "2021-10-31T16:29:18Z",
        "result": [
            {
                "label": "Not Covered",
                "value": 135
            }
        ]
    }
]

What I need to get

[
    {
        "Not Covered":132,
        "Active":0,
        "Expiring Soon":0,
        "timestamp": "2021-08-31T15:29:18Z"
    },
    {
        "Not Covered":135,
        "Active":0,
        "Expiring Soon":0,
        "timestamp": "2021-09-30T15:29:18Z"
    },
    {
        "Not Covered":135,
        "Active":0,
        "Expiring Soon":0,
        "timestamp": "2021-10-31T16:29:18Z"
    }
]

What I am doing

let flattenedResult = data.flatMap(({result,...r}) => result.map(o => ({ ...o,...r})));

const chartData = flattenedResult.reduce((acc, item) => {
    const {timestamp, value,label} = item;

    acc.push({timestamp, "Not Covered":"Not Covered"===label?value:0,"Active":"Active"===label?value:0,"Expiring Soon":"Expiring Soon"===label?value:0});
    return acc;
  }, []);

What i am getting:

[
    {
        "timestamp": "2021-08-31T15:29:18Z",
        "Not Covered": 132,
        "Active": 0,
        "Expiring Soon": 0
    },
    {
        "timestamp": "2021-09-30T15:29:18Z",
        "Not Covered": 135,
        "Active": 0,
        "Expiring Soon": 0
    },
    {
        "timestamp": "2021-10-31T16:29:18Z",
        "Not Covered": 135,
        "Active": 0,
        "Expiring Soon": 0
    }
]

Possible duplicate of stackoverflow.com/questions/68901819/… — Lakshaya U.
– Lakshaya U., Commented Sep 1, 2021 at 13:33
It is the exact same question, you can do this yourself mutating my answer. — Lakshaya U.
– Lakshaya U., Commented Sep 1, 2021 at 13:40
How is what you're getting different from what is expected in that example? You really should pick an example where there is actually a difference... — trincot
– trincot, Commented Sep 1, 2021 at 14:04

wowandy · Accepted Answer · 2022-03-31 09:26:24Z

You haven't explained how to get the values "Active" and "Expiring soon", but I'm sure something like that should help

const data = [
    {
        "timestamp": "2021-08-31T15:29:18Z",
        "result": [
            {
                "label": "Expiring Soon",
                "value": 57
            },
            {
                "label": "Not Covered",
                "value": 132
            },
            {
                "label": "Active",
                "value": 42
            }
        ]
    },
    {
        "timestamp": "2021-09-30T15:29:18Z",
        "result": [
            {
                "label": "Not Covered",
                "value": 135
            }
        ]
    },
    {
        "timestamp": "2021-10-31T16:29:18Z",
        "result": [
            {
                "label": "Not Covered",
                "value": 135
            },
            {
                "label": "Active",
                "value": 42
            }
        ]
    }
];

console.log(data.reduce((acc, {timestamp, result}) => {
    const datum = result.reduce((acc, {label, value}) => {
        acc[label] = value;
        return acc;
    }, {
        timestamp,
        'Not Covered': 0,
        Active: 0,
        'Expiring Soon': 0
    });
    return acc.concat(datum);
}, []));

if we have an object in result array with active label set it ( like if we have { "label": "Active", "value": 135 }, set "Active":135, otherwise Active or Not Covered or Expiring Soon is absent --- set it as 0 value.
so the object in resulted array must include active,Not Covered, and Expiring Soon that set as 0 in the accamulator of reduce. but if we have any of these in the data that we reducing ---> then set in accordance with that data

Caveman · Accepted Answer · 2021-09-01 15:09:59Z

What about something like this? You can then just put your "Active" and "ExpringSoon" according to your business logic.

const array = data.map(item => {
  const results = {}
  item.result.forEach(({ label, value }) => results[label] = value )
  return {
    Active: 0,
    ExpiringSoon: 0,
    timestamp: item.timestamp,
    ...results
  }
})

Result

[
  {
    Active: 0,
    ExpiringSoon: 0,
    timestamp: '2021-08-31T15:29:18Z',
    'Not Covered': 132
  },
  {
    Active: 0,
    ExpiringSoon: 0,
    timestamp: '2021-09-30T15:29:18Z',
    'Not Covered': 135
  },
  {
    Active: 0,
    ExpiringSoon: 0,
    timestamp: '2021-10-31T16:29:18Z',
    'Not Covered': 135
  }
]

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