I've got an object array which I have to group and sort:
[
{
id: 123,
group: 'abc',
metadata: {
name: 'tom'
},
date: ISODate("2019-07-08T20:33:40.475Z")
},
{
id: 456,
group: 'def',
metadata: {
name: 'bob'
},
date: ISODate("2019-07-08T20:33:40.475Z")
},
{
id: 789,
group: 'def',
metadata: {
name: 'bob'
},
date: ISODate("2019-07-10T20:33:40.475Z")
},
{
id: 234,
group: 'ghi',
metadata: {
name: 'frank'
},
date: ISODate("2019-07-10T20:33:40.475Z")
},
{
id: 567,
group: 'abc',
metadata: {
name: 'tom'
},
date: ISODate("2019-07-10T20:33:40.475Z")
}
]
Firstly I need to group the elements by the group value, then I need to sort the elements of this grouped array by date.
For grouping I've tried this:
const result = array.reduce(function (r, a) {
r[a.group] = r[a.group] || [];
r[a.group].push(a);
return r;
}, Object.create(null));
But the result is not as expected and the elements are not sorted by date.
The result could/should look something like this:
[
[
{
id: 123,
group: 'abc',
metadata: {
name: 'tom'
},
date: ISODate("2019-07-08T20:33:40.475Z")
},
{
id: 567,
group: 'abc',
metadata: {
name: 'tom'
},
date: ISODate("2019-07-10T20:33:40.475Z")
}
],
[
{
id: 456,
group: 'def',
metadata: {
name: 'bob'
},
date: ISODate("2019-07-08T20:33:40.475Z")
},
{
id: 789,
group: 'def',
metadata: {
name: 'bob'
},
date: ISODate("2019-07-10T20:33:40.475Z")
}
],
[
{
id: 234,
group: 'ghi',
metadata: {
name: 'frank'
},
date: ISODate("2019-07-10T20:33:40.475Z")
}
]
]
Use reduce
to group the values, and sort
to sort them, using map
as well due to the nested array structure.
const arr = [{id:123,group:'abc',metadata:{name:'tom'},date:"2019-07-08T20:33:40.475Z"},{id:456,group:'def',metadata:{name:'bob'},date:"2019-07-08T20:33:40.475Z"},{id:789,group:'def',metadata:{name:'bob'},date:"2019-07-10T20:33:40.475Z"},{id:234,group:'ghi',metadata:{name:'frank'},date:"2019-07-10T20:33:40.475Z"},{id:567,group:'abc',metadata:{name:'tom'},date:"2019-07-10T20:33:40.475Z"}]; const res = Object.values(arr.reduce((a, { group, ...r }) => { (a[group] = a[group] || []).push({ group, ...r }); return a; }, {})).map(e => e.sort(({ date: a }, { date: b }) => new Date(a) - new Date(b))); console.log(res);
.as-console-wrapper { max-height: 100% !important; top: auto; }
(I've taken out the ISODate
function and just kept the string date to make the snippet executable.)
I would suggest to use lodash .
var ISODate = function(str) { return str };
var data = [
{
id: 123,
group: 'abc',
metadata: {
name: 'tom'
},
date: ISODate("2019-07-08T20:33:40.475Z")
},
{
id: 456,
group: 'def',
metadata: {
name: 'bob'
},
date: ISODate("2019-07-08T20:33:40.475Z")
},
{
id: 789,
group: 'def',
metadata: {
name: 'bob'
},
date: ISODate("2019-07-10T20:33:40.475Z")
},
{
id: 234,
group: 'ghi',
metadata: {
name: 'frank'
},
date: ISODate("2019-07-10T20:33:40.475Z")
},
{
id: 567,
group: 'abc',
metadata: {
name: 'tom'
},
date: ISODate("2019-07-10T20:33:40.475Z")
}
]
console.log(
_.mapValues(
_.groupBy(data, 'group'),
function(item) { return _.orderBy(item, ['date'], ['asc']) }
)
)
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