client/src/app/helpers/rxjs.ts

   1 import { uniq } from 'lodash-es'
   2 import { Observable } from 'rxjs'
   3 import { bufferTime, distinctUntilChanged, filter, map, share, switchMap } from 'rxjs/operators'
   4
   5 function buildBulkObservable <P extends number | string, R> (options: {
   6   notifierObservable: Observable<P>
   7   time: number
   8   bulkGet: (params: P[]) => Observable<R>
   9 }) {
  10   const { notifierObservable, time, bulkGet } = options
  11
  12   return notifierObservable.pipe(
  13     distinctUntilChanged(),
  14     bufferTime(time),
  15     filter(params => params.length !== 0),
  16     map(params => uniq(params)),
  17     switchMap(params => {
  18       return bulkGet(params)
  19         .pipe(map(response => ({ params, response })))
  20     }),
  21     share()
  22   )
  23 }
  24
  25 export {
  26   buildBulkObservable
  27 }