手柄带RxJava分页 [英] Handle Paging with RxJava

问题描述

我使用的是改造+ RxJava在Android的应用程序，我问自己如何处理的API分页链的呼叫，直到所有数据被检索到。是这样的：

I'm using Retrofit + RxJava on an Android app and am asking myself about how to handle the API pagination to chain calls until all data is being retrieved. Is something like this:

Observable<ApiResponse> getResults(@Query("page") int page);

的 ApiResponse 的对象有一个简单的结构：

The ApiResponse object has a simple structure:

class ApiResponse {
    int current;
    Integer next;
    List<ResponseObject> results;
}

该API将直到最后一页返回的下一步值。

有一些实现这个好办法？尝试结合一些的 flatMaps（）的，但没有成功。

There's some good way to achieve this? Tried to combine some flatMaps(), but had no success.

推荐答案

您可以递归模型是：

Observable<ApiResponse> getPageAndNext(int page) {
  return getResults(page)
      .concatMap(new Func1<ApiResponse, Observable<ApiResponse>>() {

        @Override
        public Observable<ApiResponse> call(ApiResponse response) {
          // Terminal case.
          if (response.next == null) {
            return Observable.just(response);
          }
          return Observable.just(response)
              .concatWith(getPageAndNext(response.next));
        }

      });
}

然后，要使用它，

Then, to consume it,

getPageAndNext(0)
    .concatMap(new Func1<ApiResponse, Observable<ResponseObject>>() {

        @Override
        public Observable<ResponseObject> call(ApiResponse response) {
          return Observable.from(response.results);
        }

    })
    .subscribe(new Action1<ResponseObject>() { /** Do something with it */ });

这应该让你 ResponseObject 流将在顺序到达，并在页面大小的块最有可能到达。

That should get you a stream of ResponseObject that will arrive in order, and most likely arrive in page-size chunks.

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