change structure of array of objects to desired format-CodePudding

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.

CodePudding user response：

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);

CodePudding user response：

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();
  const currentTotal = acc?.[country]?.[status] || defaultStatus[status];
  return {
    ...acc,
    [country]: {
      ...defaultStatus,
      ...acc[country],
      [status]: currentTotal   value.count
    }
  }
}, {});

console.log(result);

CodePudding user response：

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' },
  ])
);