javascript - change structure of array of objects to desired format - Stack Overflow

admin管理员组

文章数量:1344200

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.

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.

• javascript
• arrays
• json
• object

Share Improve this question Follow edited Mar 22, 2023 at 15:33 cmgchess asked Oct 26, 2021 at 6:42 cmgchesscmgchess 10.3k4242 gold badges5353 silver badges6969 bronze badges

Add a ment  | 

3 Answers 3

Sorted by: Reset to default 1

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);

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);

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' },
  ])
);

本文标签： javascriptchange structure of array of objects to desired formatStack Overflow