Question

在this之后，我尝试用我的Firestore中的帖子填充RecyclerView。

我的Firestore的结构与链接的答案完全相同，因此我尝试复制它。我认为我的问题是我没有正确访问文档的名称。我是否必须使用.get()来检索名称？以下是我所拥有的：

private CollectionReference userFollowingReference = rootRef.collection("following/"+ currentUser.getUid()+"/UserIsFollowing");

Query first = rootRef.collection("posts/"+ userFollowingReference.getId()+"/userPosts")
                .orderBy("date", Query.Direction.DESCENDING)
                .limit(3);
        first.get().addOnCompleteListener(new OnCompleteListener<QuerySnapshot>() {
            @Override
            public void onComplete(@NonNull final Task<QuerySnapshot> task) {
                if (task.isSuccessful()) {
                    for (DocumentSnapshot document : task.getResult()) {
                        Post post = document.toObject(Post.class);
                        list.add(post);
                    }
                    followerAdapter.notifyDataSetChanged();

                    RecyclerView.OnScrollListener onScrollListener = new RecyclerView.OnScrollListener() {
                        @Override
                        public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
                            super.onScrollStateChanged(recyclerView, newState);
                            if (newState == AbsListView.OnScrollListener.SCROLL_STATE_TOUCH_SCROLL) {
                                isScrolling = true;
                            }
                        }

                        @Override
                        public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
                            super.onScrolled(recyclerView, dx, dy);
                            lastVisible = task.getResult().getDocuments().get(task.getResult().size() - 1);
                            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 = userFollowingReference.startAfter(lastVisible).limit(3);
                                nextQuery.get().addOnCompleteListener(new OnCompleteListener<QuerySnapshot>() {
                                    @Override
                                    public void onComplete(@NonNull Task<QuerySnapshot> t) {
                                        if (t.isSuccessful()) {
                                            for (DocumentSnapshot d : t.getResult()) {
                                                Post post = d.toObject(Post.class);
                                                list.add(post);
                                            }
                                            followerAdapter.notifyDataSetChanged();
                                            lastVisible = t.getResult().getDocuments().get(t.getResult().size() - 1);

                                            if (t.getResult().size() < 3) {
                                                isLastItemReached = true;
                                            }
                                        }
                                    }
                                });
                            }
                        }
                    };
                    recyclerView.addOnScrollListener(onScrollListener);
                }
            }
        });

应该从当前用户关注的所有用户那里发布帖子，但我的输出为空

编辑： 这是我的数据库的屏幕截图：子集合UserIsFollowing包含以用户关注的用户命名的文档，其唯一字段是将布尔值设置为true。

编辑2：

我更改了代码，以便首先检索关注者列表，然后使用该列表获取其帖子，但这仍然不起作用：

Query first = userFollowingReference;//TODO Realtime updates
        first.get().addOnCompleteListener(new OnCompleteListener<QuerySnapshot>() {
            @Override
            public void onComplete(@NonNull final Task<QuerySnapshot> task) {
                if (task.isSuccessful()) {
                    for (DocumentSnapshot document : task.getResult()) {
                        String id = document.getId();
                        followingList.add(id);
                    }
                    followerAdapter.notifyDataSetChanged();
                    if(!followingList.isEmpty()) {
                        Query second = rootRef.collection("posts/" + followingList.get(0) + "/userPosts")
                                .orderBy("date", Query.Direction.ASCENDING)
                                .limit(3);
                        second.get().addOnCompleteListener(new OnCompleteListener<QuerySnapshot>() {
                            @Override
                            public void onComplete(@NonNull final Task<QuerySnapshot> task) {
                                if(task.isSuccessful()) {
                                    List<Post> list = new ArrayList<>();
                                    for(DocumentSnapshot document : task.getResult()){
                                        Post post = document.toObject(Post.class);
                                        list.add(post);
                                    }
                                    recyclerView.setAdapter(followerAdapter);
                                    followerAdapter.notifyDataSetChanged();
                                    lastVisible = task.getResult().getDocuments().get(task.getResult().size() - 1);

                                    RecyclerView.OnScrollListener onScrollListener = new RecyclerView.OnScrollListener() {
                                        @Override
                                        public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
                                            super.onScrollStateChanged(recyclerView, newState);
                                            if (newState == AbsListView.OnScrollListener.SCROLL_STATE_TOUCH_SCROLL) {
                                                isScrolling = true;
                                            }
                                        }

                                        @Override
                                        public void onScrolled(final RecyclerView recyclerView, int dx, int dy) {
                                            super.onScrolled(recyclerView, dx, dy);
                                            lastVisible = task.getResult().getDocuments().get(task.getResult().size() - 1);
                                            int firstVisibleItemPosition = linearLayoutManager.findFirstVisibleItemPosition();
                                            int visibleItemCount = linearLayoutManager.getChildCount();
                                            int totalItemCount = linearLayoutManager.getItemCount();

                                            if (isScrolling && (firstVisibleItemPosition + visibleItemCount == totalItemCount) && !isLastItemReached) {
                                                isScrolling = false;
                                                Query nextQuery = rootRef.collection("posts")
                                                        .orderBy("date", Query.Direction.ASCENDING)
                                                        .startAfter(lastVisible).limit(3);
                                                nextQuery.get().addOnCompleteListener(new OnCompleteListener<QuerySnapshot>() {
                                                    @Override
                                                    public void onComplete(@NonNull Task<QuerySnapshot> t) {
                                                        if (t.isSuccessful()) {
                                                            for (DocumentSnapshot d : t.getResult()) {
                                                                Post post = d.toObject(Post.class);
                                                                postList.add(post);
                                                            }
                                                            followerAdapter.notifyDataSetChanged();
                                                            lastVisible = task.getResult().getDocuments().get(task.getResult().size() - 1);

                                                            if (t.getResult().size() < 3) {
                                                                isLastItemReached = true;
                                                            }
                                                        }
                                                    }
                                                });
                                            }
                                        }
                                    };

                                    recyclerView.addOnScrollListener(onScrollListener);
                                }

                            }
                        });
                    }
                }
            }
        });

修改3：

我收到此错误：

E/RecyclerView: No adapter attached; skipping layout
    No adapter attached; skipping layout

如何正确访问Firestore中的文档名称以填充RecyclerView？

0 个答案: