How To Get Documents Id ? Firestore Paginate

I am using Firebase Firestore Database, I am trying to load data using dual query for pagination recyclerver data, using this Stackoverflow ans link My code is for recycerview to

Solution 1:

It could be because you are sending the position and you that gives you the error, try to send final String postid=task.getResult().getDocuments().get(position-1).getId(); and see if you are getting the object that you want.Let me know it that works for you

Solution 2:

finally i solved error. the error is size of next query querysnapshot size. i use new List for saving document ids using this method on both side in first query and next quesry

           for (QueryDocumentSnapshot document : t.getResult()) {
                                                listId.add(document.getId());
                                            }

and in on Adapter get id using listId with position. final query code is

        Task<QuerySnapshot> mSnapy;
    boolean isScrolling = false;
    boolean isLastItemReached = false;
    DocumentSnapshot lastVisible;
    NewPostAdapter mNewPostAdapter;

    private void getNewFireData() {

        final int limit = 3;
        mRecyclerView = rootView.findViewById(R.id.rv_post_list);
        final LinearLayoutManager mManeger=new LinearLayoutManager(getActivity());
        mRecyclerView.setLayoutManager(mManeger);
        mRecyclerView.setHasFixedSize(true);

        mRecyclerView.invalidate();
        final List<Posts> list = new ArrayList<>();
        final List<String> listId=new ArrayList<>();

        FirebaseFirestore rootRef = FirebaseFirestore.getInstance();
        final CollectionReference postRef = rootRef.collection("posts");
        Query query = postRef.orderBy("datetime",
                Query.Direction.DESCENDING).limit(limit);
        query.get().addOnCompleteListener(new OnCompleteListener<QuerySnapshot>() {
            @Override
            public void onComplete(@NonNull Task<QuerySnapshot> task) {


                if(task.isSuccessful()){

                    lastVisible = task.getResult().getDocuments().get(task.getResult().size() - 1);

                    for (DocumentSnapshot document : task.getResult()) {
                        Posts postModel = document.toObject(Posts.class);
                        list.add(postModel);
                    }
                    for (QueryDocumentSnapshot document : task.getResult()) {
                        listId.add(document.getId());
                    }
                    mSnapy=task;
                    mNewPostAdapter = new NewPostAdapter(list,getActivity()
                            , mSnapy,listId,myContext);


                    mRecyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
                        @Override
                        public void onScrollStateChanged(@NonNull RecyclerView recyclerView, int newState) {
                            super.onScrollStateChanged(recyclerView, newState);
                            if(newState==AbsListView.OnScrollListener.SCROLL_STATE_TOUCH_SCROLL){

                                isScrolling =true;
                            }
                        }

                        @Override
                        public void onScrolled(@NonNull RecyclerView recyclerView, int dx, int dy) {
                            super.onScrolled(recyclerView, dx, dy);

                            LinearLayoutManager linearLayoutManager = ((LinearLayoutManager) recyclerView.getLayoutManager());
                            int firstVisibleItemPosition = linearLayoutManager.findFirstVisibleItemPosition();
                            int visibleItemCount = linearLayoutManager.getChildCount();
                            int totalItemCount = linearLayoutManager.getItemCount();

                            if (isScrolling && (firstVisibleItemPosition + visibleItemCount ==
                                    totalItemCount) && !isLastItemReached) {
                                isScrolling = false;
                                Query nextQuery = postRef.orderBy("datetime",
                                        Query.Direction.DESCENDING).startAfter(lastVisible).limit(limit);
                                nextQuery.get().addOnCompleteListener(new OnCompleteListener<QuerySnapshot>() {
                                    @Override
                                    public void onComplete(@NonNull Task<QuerySnapshot> t) {
                                        if (t.isSuccessful()) {
                                            for (DocumentSnapshot d : t.getResult()) {
                                                Posts productModel = d.toObject(Posts.class);
                                                list.add(productModel);

                                            }
                                            for (QueryDocumentSnapshot document : t.getResult()) {
                                                listId.add(document.getId());
                                            }
                                            mSnapy = t;
                                            System.out.println("Task Data "+mSnapy.getResult().getDocuments());
                                            mNewPostAdapter.notifyDataSetChanged();

                                            lastVisible = t.getResult().getDocuments().get(t.getResult().size() - 1);

                                            if (t.getResult().size() < limit) {
                                                isLastItemReached = true;
                                            }
                                        }
                                    }
                                });
                            }

                        }
                    });

          //          mNewPostAdapter.setHasStableIds(true);

                    mRecyclerView.setAdapter(mNewPostAdapter);


                }

            }
        });

    }

Solution 3:

I found another answer that code is below Just create a new obejct on Modal Post.class dodId and use it like below

                    for (QueryDocumentSnapshot document : task.getResult()) {
                        Posts modal=document.toObject(Posts.class);
                        modal.setDoc_id(document.getId());
                        list.add(modal);
                    }