基于嵌套键值计算对象

Question

已编辑 我有这个嵌套的 json，我想搜索一个值，然后返回找到该值的整个对象并计算这些对象并使用映射和过滤器重新创建对象。我不知道该怎么做，因为我是编程新手。

在示例 json 中，我想搜索水果的值，然后计算所有带有日期的水果的值的对象总数。

示例 Json 对象：

var sampleData = [
 {
   fruitData: {
     fruit: 'apple',
     price: 23
   },
   dateCreated: '2019-07-23T00:20:36.535Z'
 },
 {
   fruitData: {
     fruit: 'apple',
     price: 36 
   },
   dateCreated: '2019-07-23T00:30:32.135Z'
 },
 {
   fruitData: {
     fruit: 'apple',
     price: 36 
   },
   dateCreated: '2019-07-24T00:10:36.115Z'
 },
 {
   fruitData: {
     fruit: 'mango',
     price: 40 
   },
   dateCreated: '2019-07-24T01:25:32.835Z'
 },
]

我希望输出是这样的，并在搜索水果的价值后计数

var filteredData= [
 {
   '07-23-2019': {
       'apple': 2
   },
   '07-24-2019': {
       'apple': 1,
       'mango': 1
   }
 }
]

感谢那些愿意提供帮助的人

Answer 1

假设JSON是结构化的，我们可以得到fruits的值：

function fruitCount(sampleData) {
    var results = {};

    // sampleData is a list, so for each item
    sampleData.forEach((container) => {

        // Get the relevant data from the subfields.
        let date = container.dateCreated;
        let fruit = container.fruitData.fruit;

        // If the date has been found before, we'll reuse it.
        // If the fruit has been found before, we'll increment it.
        // If the fruit has NOT been found before, we'll insert it with a
        //     value of 1.
        if (date in results) {
            results[date][fruit] = results[date][fruit] + 1 || 1;

        // The date has not been found before, so create it.
        } else {
            results[date] = {fruit: 1};
        }
    });

    return results;
}

if (date in results) {
    results[date][fruit] = results[date][fruit] + 1 || 1;

相当于

if (date in results) {
    if (fruit in results[date]) {
        results[date][fruit]++;
    } else {
        results[date][fruit] = 1;
    }
}

Answer 2

const sampleData = [
    {
        fruitData: {
            fruit: 'apple',
            price: 23
        },
        dateCreated: '07-23-2019'
    },
    {
        fruitData: {
            fruit: 'apple',
            price: 36
        },
        dateCreated: '07-23-2019'
    },
    {
        fruitData: {
            fruit: 'mango',
            price: 40
        },
        dateCreated: '07-23-2019'
    },
];


function groupData(data, key) {
    const objs = {};
    for (const obj of data) {
        objs[obj[key].fruit] = (objs[obj[key].fruit] || 0) + 1;
    }
    return objs;
}

const data = groupData(sampleData, 'fruitData');

如果你希望数据是一个数组，那么把最后一行改成这个

const data = [groupData(sampleData, 'fruitData')];