NodeJS example - RxJS - Processing S3 Event keys and group them by account id

events-group-by-account-id.js

/**
* https://repl.it/@marquesanderson/pongo-aggregation-events-by-account-id
*/
const RxJS = require('rxjs')
const filter = require('rxjs/operators').filter
const map = require('rxjs/operators').map
const groupBy = require('rxjs/operators').groupBy
const flatMap = require('rxjs/operators').flatMap
const toArray = require('rxjs/operators').toArray

let eventKeys$ = RxJS.from([
  '2019/05/30/16/23/api-call/2/xpto-xpto-1',
  '2019/05/30/16/24/api-call/2/xpto-xpto-2',
  '2019/05/30/16/25/api-call/2/xpto-xpto-3',
  '2019/05/30/16/21/api-call/1/xpto-xpto-4',
  '2019/05/30/16/21/api-call/1/xpto-xpto-5'
])

eventKeys$.pipe(
  map((eventKey) => {
    const eventKeyParts = eventKey.split('/')
    return {
      accountId: eventKeyParts[6],
      eventKey: eventKey,
      eventName: eventKeyParts[5]
    }
  }),
  filter(e => e.eventName === 'api-call'),
  groupBy(e => e.accountId),
  flatMap(group => { 
    return group.pipe(toArray())
  }),
  map((group) => {
    return {
      accountId: group[0].accountId,
      events: group.map(event => {
        return event.eventKey
      })
    }
  })
).subscribe((data) => console.log(data))

/** 

Result:

{ accountId: '2',
  events:
   [ '2019/05/30/16/23/api-call/2/xpto-xpto-1',
     '2019/05/30/16/24/api-call/2/xpto-xpto-2',
     '2019/05/30/16/25/api-call/2/xpto-xpto-3' ] }
{ accountId: '1',
  events:
   [ '2019/05/30/16/21/api-call/1/xpto-xpto-4',
     '2019/05/30/16/21/api-call/1/xpto-xpto-5' ] }
*/