如何使用 Retrofit 和 RxJava 重试对餐馆的相同搜索查询以从 Google Map Api 获取下一页结果

Question

I'm doing request to Google Map, to get a list of restaurants, using the Nearby Search Api. https://developers.google.com/maps/documentation/places/web-service/search-nearby The server sends its response through pages containing a maximum of 20 results. If an extra page is available, the json next_page_token attribute is set, containing the value to be passed as a parameter to the next search. Using retrofit and RxJava, I know how to do the first search, and get the next_page_token. But I don't know how to retry the same request. Any help will be appreciated.

public Observable<PlaceNearbySearch> streamFetchRestaurants(String location, int radius, String type) {
// search for the list of restaurants
    RestoApi restoApi = RetrofitBuilder.getRetrofit().create(RestoApi.class);
        return restoApi.getRestoFirsttPage(location, radius, type, GOOGLE_MAP_API_KEY) 
                .subscribeOn(Schedulers.io())
                .observeOn(AndroidSchedulers.mainThread())
                .timeout(10, TimeUnit.SECONDS);
}
public Observable<PlaceDetail> streamFetchDetails(String placeId) {
// search details for each restaurants of the list
RestoApi restoApi = RetrofitBuilder.getRetrofit().create(RestoApi.class);
return restoApi.getPlaceDetails(placeId, GOOGLE_MAP_API_KEY)
        .subscribeOn(Schedulers.io())
        .observeOn(AndroidSchedulers.mainThread())
        .timeout(10, TimeUnit.SECONDS);
}

public Single<List<PlaceDetail>> streamFetchRestaurantDetails(String location, int radius, String type) {
// chains the 2 previous requests
    return streamFetchRestaurants(location, radius, type)
            .flatMapIterable(new Function<PlaceNearbySearch, List<PlaceNearbySearchPlace>>() {
                @Override
                public List<PlaceNearbySearchPlace> apply(PlaceNearbySearch placeNearbySearch) throws Exception {
                    // Is next_page_token set?
                    // In case it is, how would you query the next page??
                    Log.d(TAG, "apply: next_page_token: " + placeNearbySearch.getNext_page_token());
                    return placeNearbySearch.getResultSearches();

                }
            })
            .flatMap(new Function<PlaceNearbySearchPlace, Observable<PlaceDetail>>() {
                @Override
                public Observable<PlaceDetail> apply(PlaceNearbySearchPlace placeNearbySearchPlace) throws Exception {
                    return streamFetchDetails(placeNearbySearchPlace.getPlaceId());
                }
            })
            .toList()
            .subscribeOn(Schedulers.io())
            .observeOn(AndroidSchedulers.mainThread());
}

private void test_streamFetchRestaurantDetails() throws InterruptedException {
// test method
    String location = "48.854685336064264, 2.3467574997969596";
    int radius = 1500;
    String type = "restaurant";
    callstreamFetchRestaurantDetails(location, radius, type);
}

private void callstreamFetchRestaurantDetails(String location, int radius, String type) {
    streamFetchRestaurantDetails(location, radius, type)
            .subscribe(new DisposableSingleObserver<List<PlaceDetail>>() {
                @RequiresApi(api = Build.VERSION_CODES.N)
                @Override
                public void onSuccess(@io.reactivex.rxjava3.annotations.NonNull List<PlaceDetail> placeDetails) {
                    // handle list of placeDetails
                }

                @Override
                public void onError(@io.reactivex.rxjava3.annotations.NonNull Throwable e) {
                    Log.d(TAG, "onError: " + e.getMessage());
                }
            });
}

Answer 1

You need to use the "next_page_token" this will return you the next 20 results. If there are no more results available it will not send you the next_page_token. Check this document for usage of this token.