映射数组的对象到映射分组的对象键js不可变

Question

我想映射一个数组的对象到输出的Immutable map按特定的对象键分组。

array looks like
[
 {id:1, time:19072016},
 {id:2, time:19072016},
 {id:3, time:19072015},
]
output im seeking is
[
 byId: {
  1:{id:1, time:19072016},
  2:{id:2, time:19072016},
  3:{id:3, time:19072015},
 },
 byTime: {
  19072016:[1,2],
  19072015:[3],
 }
]

使用immutablejs或seamless-immutable最有效的方法是什么?

当前使用的是reduce:

array.reduce( (final,row) =>final.setIn(['byId',row.id],row) ,
              Immutable.Map({byId:{},byTime:{}});

这个输出byIds，因为我想要它，但byTime的问题是，我需要合并而不是覆盖。

i tried with seamless-immutable i did:

Seamless(arr).toObject(i=>[i.id,i]) //this will return byId as i want it
Seamless(arr).toObject(i=>[i.time,[i.id]]) //this will not merge [1,2] :(

Answer 1

你可以通过使用.groupBy()和.map()得到你想要的。

const data = Immutable.fromJS([
  {id:1, time:19072016},
  {id:2, time:19072016},
  {id:3, time:19072015},
]);
const byId = data
  .groupBy(item => item.get('id'))
  .map(items => items.first());
console.log(byId);
const byTime = data
  .groupBy(item => item.get('time'))
  .map(items => items.map(item => item.get('id')));
console.log(byTime);

<script src="https://cdnjs.cloudflare.com/ajax/libs/immutable/3.8.2/immutable.js"></script>