將物件陣列的結構更改為所需格式

我正在構建一個 API 并以給定的格式從我的資料庫中獲取資料。
不會有類似的重復{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'}
]

但我想在發送之前將我的資料轉換為不同的格式。

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
  }
}

我該如何解決這個問題。

uj5u.com熱心網友回復：

您可以使用 .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 result = dataFromDB.reduce((acc, value)=> {
  const country = value.country.toLowerCase();
  const status = value.status.toLowerCase();
  const currentTotal = acc?.[country]?.[status] || 0;
  return {
    ...acc,
    [country]: {
      ...acc[country],
      [status]: currentTotal   value.count
    }
  }
}, {});

console.log(result);

uj5u.com熱心網友回復：

只需通過array普通回圈objects并使用每個資料創建一個具有不同鍵的新物件。這例如

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' },
  ])
);

uj5u.com熱心網友回復：

要將資料轉換為您想要的格式，我們可以創建一個物件formatIWant，然后遍歷dataFromDB，同時使用相關資料更新該物件。

這是一個簡單的實作，它將產生您正在尋找的結果。

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);

標籤：javascript 节点.js 数组 json 目的

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