使用 RxJs forkJoin 将多个 api 调用合并到单个 output 数组中

Question

Let's say I have 4 API calls. In this case, each of the 4 calls return the same data structure so I don't need to manipulate the return types. They each return an array of objects. I'd like to call them all, but combine them into on output array. I tried combining forkJoin with .concat( ) but that didn't do what I expected (it put them inside of smaller arrays).

forkJoin([
  this.service.getData('something', 'somethingelse'),
  this.service.getData('something1', 'somethingelse2')
].concat()).subscribe(data => console.log(data))

Answer 1

Consider the following implementation: (concating the arrays is performed once data has been returned)

forkJoin([
  this.service.getData('something', 'somethingelse'),
  this.service.getData('something1', 'somethingelse2')
])
.pipe(
  map(x => x.reduce((arr, curr) => [...arr,...curr]))
)
.subscribe(data => console.log(data))

Or using ES2019 flat

forkJoin([
  this.service.getData('something', 'somethingelse'),
  this.service.getData('something1', 'somethingelse2')
])
.pipe(
  map(x => x.flat())
)
.subscribe(data => console.log(data))