File paging with volley

File Service
1

So I want to fetch images for a wallpaper app in android without using Backendless API.I used volley and it works but when I am using “pageSize” and “offset” as stated in one of docs.I am getting some files repeated in next set of images.

2

Hi Vikram

Please provide us request examples what return duplicates, maybe CURLs or a code snippet what we can run to reproduce the issue

Regards, Vlad

3

Hi here is a snippet from my android code.I am getting same files repeated some times.I am getting files from a folder in Backendless’s FILE system.

 mRecyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
        @Override
        public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
            super.onScrolled(recyclerView, dx, dy);

            visibleItemCounter = mRecyclerView.getChildCount();
            totalItemCounter = mGridLayoutManager.getItemCount();
            firstVisibleItem = mGridLayoutManager.findFirstVisibleItemPosition();

            if (processingNewItem) {
                if (totalItemCounter > previousTotalItem) {
                    processingNewItem = false;
                    previousTotalItem = totalItemCounter;
                    pageCounter++;
                }
            }

            if (!processingNewItem && (totalItemCounter - visibleItemCounter) <= (firstVisibleItem + visibleThresholdItem)) {
                Snackbar.make(mRecyclerView, "Loading More Pictures...",
                        Snackbar.LENGTH_LONG).show();
                mPictureUrl = ApiUrls.PICTURE_BASE_URL + "?"+ApiUrls.PAGE_OFFSET + "=" + String.valueOf(pageCounter) +
                        "&" + ApiUrls.PER_PAGE_ITEM_OFFSET + "=" + "15";
                getPictureListData(mPictureUrl);
                Log.d(TAG,mPictureUrl);
                processingNewItem = true;
            }
        }
4

And also pay attention, that if you added the records to the table between two ‘get’ requests, then it can happen.

5

There is no other CRUD methods in my app except GET.
https://api.backendless.com/APPID/RESTAPIKEY/files/FOLDERNAME?offset=1&pagesize15;
https://api.backendless.com/APPID/RESTAPIKEY/files/FOLDERNAME?offset=2&pagesize15;
and so on is the api call precisely.

6

I see, you use wrong “offset” it should be 0 for the first request and 15 for the second
see the doc: https://backendless.com/docs/js/data_data_paging.html

7

‘offset’ means the amount of records that must be skipped.

8

Thank you for the help I managed to solve it.Great community.
Is there a way to generate thumbnail for all images using Backendless.

9

Thank you for the quick help.It works now.

10

Please, see this article. It may help you to understand how to use backendless to create thumbnails.
https://backendless.com/how-to-split-images-into-small-medium-and-high-resolutions-with-backendless-api-service/