change structure of array of objects to desired format

Question

I'm building an API and getting the data from my database in the given format.
There won't be repetitions like {country: 'India', count: 2, status: 'Active'},{country: 'India', count: 1, status: 'Active'}

const dataFromDB = [
{country: 'India', count: 2, status: 'Active'}, {country: 'USA', count: 3, status: 'Recovered'}, 
{country: 'India', count: 2, status: 'Recovered'}, {country: 'Russia', count: 1, status: 'Active'},
{country: 'India', count: 1, status: 'Dead'}, {country: 'Brazil', count: 1, status: 'Active'}, 
{country: 'Canada', count: 1, status: 'Dead'}, {country: 'USA', count: 1, status: 'Active'}
]

But I want to convert my data into a different format before sending it out.

const formatIWant = {
  Brazil: {
    active: 1,
    dead: 0,
    recovered: 0
  },
  Canada: {
    active: 0,
    dead: 1,
    recovered: 0
  },
  India: {
    active: 2,
    dead: 1,
    recovered: 2
  },
  Russia: {
    active: 1,
    dead: 0,
    recovered: 0
  },
  USA: {
    active: 1,
    dead: 0,
    recovered: 3
  }
}

How do I tackle this problem.

Dharman · Accepted Answer · 2021-10-26 07:32:24Z

To convert the data into your desired format, we can create an object, formatIWant, then iterate through dataFromDB, updating that object with the relevant data as we go.

Here's a simple implementation that will yield the result you are looking for.

const dataFromDB = [
    {country: 'India', count: 2, status: 'Active'},
    {country: 'USA', count: 3, status: 'Recovered'},
    {country: 'India', count: 2, status: 'Recovered'},
    {country: 'Russia', count: 1, status: 'Active'},
    {country: 'India', count: 1, status: 'Dead'},
    {country: 'Brazil', count: 1, status: 'Active'},
    {country: 'Canada', count: 1, status: 'Dead'},
    {country: 'USA', count: 1, status: 'Active'}
]


const formatIWant = {};

for(let i=0; i<dataFromDB.length; i++){
    
    let country = dataFromDB[i].country;
    let count = dataFromDB[i].count;
    let status = dataFromDB[i].status;
    
    // add entry for country if not found
    !formatIWant[country] ? formatIWant[country] = {
        active: 0,
        dead: 0,
        recovered: 0
    } : '';
    
    // update country with data
    formatIWant[country][status.toLowerCase()] = count;

}

console.log(formatIWant);

Ro Milton · Accepted Answer · 2021-10-26 22:28:39Z

You can use .reduce()

const dataFromDB = [
{country: 'India', count: 2, status: 'Active'}, {country: 'USA', count: 3, status: 'Recovered'}, 
{country: 'India', count: 2, status: 'Recovered'}, {country: 'Russia', count: 1, status: 'Active'},
{country: 'India', count: 1, status: 'Dead'}, {country: 'Brazil', count: 1, status: 'Active'}, 
{country: 'Canada', count: 1, status: 'Dead'}, {country: 'USA', count: 1, status: 'Active'}
];

const defaultStatus = dataFromDB.reduce((acc, {status}) =>
  acc.hasOwnProperty(status.toLowerCase())
    ? acc
    : {...acc, [status.toLowerCase()]: 0}
, {});

const result = dataFromDB.reduce((acc, value)=> {
  const country = value.country.toLowerCase();
  const status = value.status.toLowerCase();
  return {
    ...acc,
    [country]: {
      ...defaultStatus,
      ...acc[country],
      [status]: value.count
    }
  }
}, {});

console.log(result);

cmgchess · Accepted Answer · 2021-10-26 10:28:34Z

0

Just loop thru the array of plain objects and create a new object with different keys using each data. This for example

const reformat = (dataFromDB) => {
  const formatted = {};

  for (const data of dataFromDB) {
    formatted[data.country] = {
      recovered: 0,
      active: 0,
      dead: 0,
      ...formatted[data.country],
      [data.status.toLowerCase()]: data.count,
    };
  }

  return formatted;
};

console.log(
  reformat([
    { country: 'India', count: 2, status: 'Active' },
    { country: 'USA', count: 3, status: 'Recovered' },
    { country: 'India', count: 2, status: 'Recovered' },
    { country: 'Russia', count: 1, status: 'Active' },
    { country: 'India', count: 1, status: 'Dead' },
    { country: 'Brazil', count: 1, status: 'Active' },
    { country: 'Canada', count: 1, status: 'Dead' },
    { country: 'USA', count: 1, status: 'Active' },
  ])
);

edited Oct 26, 2021 at 10:28

cmgchess

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answered Oct 26, 2021 at 6:56

JP Calvo

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3 Comments

cmgchess Over a year ago

but this will overwrite every country object and will give only last value?

JP Calvo Over a year ago

Already updated it. Just added one line (the spread operator for existing values). Goodluck! You could also add default zero values for other keys if you want them to be. Just add the proper keys with zero values before the spread operator.

JP Calvo Over a year ago

Made another update. I have already tested it

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