loDash-对数组进行分组并填充数组 [英] lodash - group and populate arrays

问题描述

使用lodash，我如何将生日相同的人的姓名分组，如下所示？

我使用嵌套的for循环写出了这一点，但是我想在lodash中会有一种更优雅的方式来实现这一点。我没怎么用过，想知道该用哪种功能。

[
    { "birthdate": "1993", "name": "Ben" },
    { "birthdate": "1994", "name": "John" },
    { "birthdate": "1995", "name": "Larry" },
    { "birthdate": "1995", "name": "Nicole" },
    { "birthdate": "1996", "name": "Jane" },
    { "birthdate": "1996", "name": "Janet" },
    { "birthdate": "1996", "name": "Dora" },
]

至

[
    { "birthdate": "1993", "names": [ "Ben" ] }, 
    { "birthdate": "1994", "names": [ "John"] },
    { "birthdate": "1995", "names": [ "Larry", "Nicole" ] }, 
    { "birthdate": "1996", "names": [ "Jane", "Janet", "Dora" ] }        
]

推荐答案

您可以使用groupBy()按birthdate对集合中的每一项进行分组。对项目进行分组后，可以使用map()迭代每个组，并将其形成包含birthdate和names的新格式。若要从分组的项目中获取名称数组，可以再次使用map()函数返回所有name值。

var result = _(source)
    .groupBy('birthdate')
    .map(function(items, bdate) {
      return {
        birthdate: bdate,
        names: _.map(items, 'name')
      };
    }).value();

var source = [
    { "birthdate": "1993", "name": "Ben" },
    { "birthdate": "1994", "name": "John" },
    { "birthdate": "1995", "name": "Larry" },
    { "birthdate": "1995", "name": "Nicole" },
    { "birthdate": "1996", "name": "Jane" },
    { "birthdate": "1996", "name": "Janet" },
    { "birthdate": "1996", "name": "Dora" },
];
  
var result = _(source)
    .groupBy('birthdate')
    .map(function(items, bdate) {
      return {
        birthdate: bdate,
        names: _.map(items, 'name')
      };
    }).value();

document.body.innerHTML = '<pre>' + JSON.stringify(result, 0, 4) + '</pre>';

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.4/lodash.js"></script>

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