Question

如果具有相同的ID，我想将值合并到数组。我有一个这样的对象数组。

[ 
 { 
   id: 'Tony',
   type: 'hero',
   favorite: 'Rosie',
 },
 { 
   id: 'Jane',
   type: 'human',
   favorite: null,
 },
 { 
   id: 'Tony',
   type: 'hero',
   favorite: 'Lisa',
 },
 { 
   id: 'Steve',
   type: 'hero',
   favorite: 'Jennie',
 },
 { 
   id: 'Tony',
   type: 'hero',
   favorite: 'Jisoo',
 },
]

，我想将键favorite从字符串合并到数组。我想要这样的输出

[ 
 { 
   id: 'Tony',
   type: 'hero',
   favorite: ['Rosie', 'Lisa', 'Jisoo'],
 },
 { 
   id: 'Jane',
   type: 'human',
   favorite: null,
 },
 { 
   id: 'Steve',
   type: 'hero',
   favorite: ['Jennie'],
 }

并且我尝试编写如下代码：（from：Sum similar keys in an array of objects）

var obj = [
    {
      id: 'Tony',
      type: 'hero',
      favorite: 'Rosie',
    },
    {
      id: 'Jane',
      type: 'human',
      favorite: null,
    },
    {
      id: 'Tony',
      type: 'hero',
      favorite: 'Lisa',
    },
    {
      id: 'Steve',
      type: 'hero',
      favorite: 'Jennie',
    },
    {
      id: 'Tony',
      type: 'hero',
      favorite: 'Jisoo',
    },
  ];

  var holder = {};
  const ar = []
  obj.forEach(function (d) {
    if (holder.hasOwnProperty(d.id)) {
      holder[d.id] = ar.push(holder[d.id] + d.favorite);
    } else {
      holder[d.id] = d.favorite;
    }
  });

  var obj2 = [];

  for (var prop in holder) {
    obj2.push({ name: prop, favorite: holder[prop] });
  }

  console.log(obj2);

但是卖出的是

[ { name: 'Tony', favorite: 2 },
  { name: 'Jane', favorite: null },
  { name: 'Steve', favorite: 'Jennie' } ]

我该怎么做？

Answer 1

您可以使用单个Array.reduce进行此操作，这很可能是最简单，最有效的方法：

var data = [ { id: 'Tony', type: 'hero', favorite: 'Rosie', }, { id: 'Jane', type: 'human', favorite: null, }, { id: 'Tony', type: 'hero', favorite: 'Lisa', }, { id: 'Steve', type: 'hero', favorite: 'Jennie', }, { id: 'Tony', type: 'hero', favorite: 'Jisoo', }, ]

let result = data.reduce((r, {id,type,favorite}) => {
  r[id] = r[id] || {id, type, favorite: []}
  r[id].favorite.push(favorite)
  return r
}, {})

console.log(Object.values(result))

这个想法是对id进行“分组”，然后在每次迭代时继续推送到favorites数组。

对于ES5，您可以按照类似的方式进行操作：

var data = [ { id: 'Tony', type: 'hero', favorite: 'Rosie', }, { id: 'Jane', type: 'human', favorite: null, }, { id: 'Tony', type: 'hero', favorite: 'Lisa', }, { id: 'Steve', type: 'hero', favorite: 'Jennie', }, { id: 'Tony', type: 'hero', favorite: 'Jisoo', }, ]

let result = data.reduce(function(r, c){
   r[c.id] = r[c.id] || {id: c.id, type: c.type, favorite: []}
   r[c.id].favorite.push(c.favorite)
   return r
}, {})

console.log(Object.values(result))

lodash确实不需要实现这一点。

Answer 2

将id与_.group()分组，然后使用_.map()和_.mergeWith()合并每个分组，并将favorite收集到一个数组中：

const data = [{"id":"Tony","type":"hero","favorite":"Rosie"},{"id":"Jane","type":"human","favorite":null},{"id":"Tony","type":"hero","favorite":"Lisa"},{"id":"Steve","type":"hero","favorite":"Jennie"},{"id":"Tony","type":"hero","favorite":"Jisoo"}]

const result = _(data)
  .groupBy('id')
  .map(g => _.mergeWith({}, ...g, (o, s, k) => {
    if(k !== 'favorite') return // non favorite key are not collected to an array
    
    if(_.isNil(s)) return o // don't add null or undefined to array
    
    return [].concat(o || [], s) // concat other values to array
  }))
  .value()
  
console.log(result)

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.11/lodash.js"></script>

Answer 3

在将favorite属性转换为数组之后，只需遍历数组并构造一个新数组，然后对于具有相同id的下一个元素，推入favorite数组

let users = [{id: 'Tony', type: 'hero', favorite: 'Rosie',}, {id: 'Jane', type: 'human', favorite: null,}, {id: 'Tony', type: 'hero', favorite: 'Lisa',}, {id: 'Steve', type: 'hero', favorite: 'Jennie',}, {id: 'Tony', type: 'hero', favorite: 'Jisoo',},];

// To combine friends of the same user in an array at property friendNames
let merged = {};
for (let user of users) {
    if (typeof merged[user.id] === 'undefined') {
        user.favorite = [user.favorite];
        merged[user.id] = user;
    } else {
        merged[user.id].favorite.push(user.favorite)
    }
}

console.log(Object.values(merged));

Answer 4

使用map和Set获得此结果。

首先，我们使用Set字段创建一个新的唯一id。

我们从中播种一个新的新array并调用map方法。

const arr = [ 
 { 
   id: 'Tony',
   type: 'hero',
   favorite: 'Rosie',
 },
 { 
   id: 'Jane',
   type: 'human',
   favorite: null,
 },
 { 
   id: 'Tony',
   type: 'hero',
   favorite: 'Lisa',
 },
 { 
   id: 'Steve',
   type: 'hero',
   favorite: 'Jennie',
 },
 { 
   id: 'Tony',
   type: 'hero',
   favorite: 'Jisoo',
 },
];

const masterArr = [...new Set(arr.map((e) => e.id))].map(a => ({
  id: a,
  type: arr.find(x => x.id === a).type,
  favorites: arr.filter(x => x.id === a).map(y => y.favorite)
}));

console.log(masterArr);

Answer 5

您可以在数组上使用reduce。

const arr = [ 
 { 
   id: 'Tony',
   type: 'hero',
   favorite: 'Rosie',
 },
 { 
   id: 'Jane',
   type: 'human',
   favorite: null,
 },
 { 
   id: 'Tony',
   type: 'hero',
   favorite: 'Lisa',
 },
 { 
   id: 'Steve',
   type: 'hero',
   favorite: 'Jennie',
 },
 { 
   id: 'Tony',
   type: 'hero',
   favorite: 'Jisoo',
 },
]
const out = arr.reduce((result, el)=> {
    const id = result.findIndex(e => e.id ===el.id)

    if(id> -1){
        result[id] = {...result[id], favorite: [...result[id].favorite, el.favorite]}
    } else {result.push({...el, favorite: [el.favorite].filter(x => x) })}
    return result
}, [])
console.log(out)

Answer 6

与Lodash：

var data = [ { id: 'Tony', type: 'hero', favorite: 'Rosie', }, { id: 'Jane', type: 'human', favorite: null, }, { id: 'Tony', type: 'hero', favorite: 'Lisa', }, { id: 'Steve', type: 'hero', favorite: 'Jennie', }, { id: 'Tony', type: 'hero', favorite: 'Jisoo', }, ]


var result = _(data).groupBy(a => a.id).map((objs, key) => ({
        'id': key,
        'type': _.head(objs).type,
        'favorite': _.map(objs, 'favorite')
    }))
    .value();

console.log(result);

<script src="https://cdn.jsdelivr.net/lodash/4.17.2/lodash.min.js"></script>

如果ID相同，如何将数组对象值合并到数组中

6 个答案: