Turning paginated requests into an Observable stream with RxJs

Question

I have a service which returns data in pages. The response to one page contains details on how to query for the next page.

My approach is to return the response data

Answer 1

EDIT Ah! I see the problem you're facing. A bit of tail call optimization should fix you up:

function mockGetPageAjaxCall(index) {
  // return dummy data for testcase
  return Promise.resolve({nextpage:index+1, data:[1,2,3]});
}

function getPageFromServer(index) {
  return Observable.create(function(obs) {
    mockGetPageAjaxCall(index).then(function(page) {
      obs.onNext(page);
    }).catch(function(err) {
      obs.onError(err)
    }).finally(function() {
      obs.onCompleted();
    });
  });
}

function getPagedItems(index) {
    return Observable.create(function(obs) {
        // create a delegate to do the work
        var disposable = new SerialDisposable();
        var recur = function(index) {
            disposable.setDisposable(getPageFromServer(index).retry().subscribe(function(page) {
                obs.onNext(page.items);
                if(page.nextpage === null) {
                  obs.onCompleted();   
                }

                // call the delegate recursively
                recur(page.nextpage);
            }));
        };

        // call the delegate to start it
        recur(0);

        return disposable;
    });
}

getPagedItems(0).subscribe(
  function(item) {
    console.log(new Date(), item);
  },
  function(error) {
    console.log(error);
  }
)