How to put objects in an array into new array sorting by date?

Question

I want to use SectionList in React Native. Datas that SectionList needs to render looks like this:

sections=[
 {
   date: 'May 24 2019', 
   data: [
     {
       id:1,
       msg: 'msg1',
       date: 'May 24 2019'
     },
     {
       id:2,
       msg: 'msg2',
       date: 'May 24 2019'
     },
 ]},
 {
   date: 'May 25 2019', 
   data: [
     {
       id:3,
       msg: 'msg1',
       date: 'May 25 2019'
     },
     {
       id:4,
       msg: 'msg2',
       date: 'May 25 2019'
     },
 ]},
];

But data that I receive from server looks like this:

data:[
  {
       id:1,
       msg: 'msg1',
       date: 'May 24 2019'
  },
  {
       id:2,
       msg: 'msg2',
       date: 'May 24 2019'
  },
  {
       id:3,
       msg: 'msg1',
       date: 'May 25 2019'
  },
  {
       id:4,
       msg: 'msg1',
       date: 'May 25 2019'
  },
];

So how can I convert "data" to look like "sections". I appreciate your help. And sorry for my English.

The wrapping object literals {} in your output are wrong. They should be removed — Maheer Ali
– Maheer Ali, Commented May 23, 2019 at 7:05

Akrion · Accepted Answer · 2019-05-23 07:22:57Z

2

You could use Array.reduce to create the actual grouping and then extract the values via Object.values:

let data = [ { id:1, msg: 'msg1', date: 'May 24 2019' }, { id:2, msg: 'msg2', date: 'May 24 2019' }, { id:3, msg: 'msg1', date: 'May 25 2019' }, { id:4, msg: 'msg1', date: 'May 25 2019' }, ];

let result = data.reduce((r,{ date, ...other}) => {
  r[date] = r[date] || { date, data: [] }
  r[date].data = [...r[date].data, { date, ...other }]
  return r
}, {})

console.log(Object.values(result))

edited May 23, 2019 at 7:22

answered May 23, 2019 at 7:10

Akrion

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Comments

Maheer Ali · Accepted Answer · 2019-05-23 07:15:28Z

1

You can do that in following steps:

Use reduce() to build up an an object whose keys will different dates and values will be array containing items
Then get values of that object using Object.values()
Then use map() on that and add additional property date and return the object.

const data = [ { id:1, msg: 'msg1', date: 'May 24 2019' }, { id:2, msg: 'msg2', date: 'May 24 2019' }, { id:3, msg: 'msg1', date: 'May 25 2019' }, { id:4, msg: 'msg1', date: 'May 25 2019' }, ]

const res = Object.values(
                  data.reduce((ac,a) => (ac[a.date] = (ac[a.date] || []).concat(a),ac),{})
             ).map(x => ({data:[...x],date:x[0].date}))

console.log(res)

edited May 23, 2019 at 7:15

answered May 23, 2019 at 7:10

Maheer Ali

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Comments

iambinodstha · Accepted Answer · 2019-05-23 11:26:26Z

0

let data = [
    {
        id: 1,
        msg: 'msg1',
        date: 'May 24 2019'
    },
    {
        id: 2,
        msg: 'msg2',
        date: 'May 24 2019'
    },
    {
        id: 3,
        msg: 'msg1',
        date: 'May 25 2019'
    },
    {
        id: 4,
        msg: 'msg1',
        date: 'May 25 2019'
    },
];

let result = {}

data.map(val=>{
    if(result[val.date]){
        return result[val.date] = {...result[val.date], value: [...result[val.date].value, val]}
    }else{
        return result[val.date] = {date: val.date, value: [val]}
    }
})

console.log(Object.values(result));

answered May 23, 2019 at 11:26

iambinodstha

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