RxJs Observable Pagination

Question

First: This is the first project in which I am using RxJs, I thought I will learn best by using it.

I found this answer: Turning paginated requests into an Observabl

Answer 1

Here is my solution using the rxjs operators expand, reduce and empty using the HttpClient module:

Suppose your API response is an object containing shaped like the following

interface Response {
  data: items[]; // array of result items
  next: string|null; // url of next page, or null if there are no more items
}

You could use expand and reduce like so

getAllResults(url) {
  return this.http.get(url).pipe(
    expand((res) => res.next ? this.http.get(res.next) : EMPTY),
    reduce((acc, res) => acc.concat(res.data), [])
  );
}