问题
I wanted to query firestore database with the timestamp recently posted For ex: I have collection of posts Indexed with timestamp ascending and descending order when the user opens the feed it will show the today's date(timestamp Today Descending ) Posts. when the user scrolls it fetches next 3 ids and so on and ends with last item of today.But without ending with last item post of today I wanted to show the next day posts and so on for last seven days so the recycler view will be endless like instagram or fb feed. the initial try method was to get the recently posted post alone of timestamp.
private int limit = 3;
private int PostLimit = 1;
private void ReadingPosts() {
String userId = FirebaseAuth.getInstance().getUid();
FirebaseFirestore db = FirebaseFirestore.getInstance();
Calendar calendar = Calendar.getInstance();
final Date currentTime = Calendar.getInstance().getTime();
calendar.setTime(currentTime);
calendar.add(Calendar.DAY_OF_YEAR, - 7);
final Date pastThreeDays = calendar.getTime();
followingList.add(userId);
final CollectionReference UserRef = db.collection("UserPosts");
Query query = UserRef.limit(limit);
query.get().addOnCompleteListener(new OnCompleteListener<QuerySnapshot>() {
@Override
public void onComplete(@NonNull final Task<QuerySnapshot> task) {
if (task.isSuccessful()) {
for (QueryDocumentSnapshot documentSnapshot : task.getResult()) {
for (String id : followingList) {
if (documentSnapshot.getId().equals(id)) {
Log.d(TAG, "onComplete: IDS3 :" + id);
FirebaseFirestore db = FirebaseFirestore.getInstance();
CollectionReference PostRef = db.collection("UserPosts")
.document(id)
.collection("Posts");
Query query = PostRef.orderBy("timestamp", Query.Direction.DESCENDING).limit(PostLimit);
query.get().addOnCompleteListener(new OnCompleteListener<QuerySnapshot>() {
@Override
public void onComplete(@NonNull Task<QuerySnapshot> task) {
if (task.isSuccessful()) {
for (QueryDocumentSnapshot documentSnapshot1 : task.getResult()) {
Posts posts = documentSnapshot1.toObject(Posts.class);
postsList.add(posts);
}
}
postsAdapter.notifyDataSetChanged();
swipeRefreshLayout.setRefreshing(false);
}
})
.addOnFailureListener(new OnFailureListener() {
@Override
public void onFailure(@NonNull Exception e) {
Log.d(TAG, "onFailure: Failed to get the posts");
}
});
}
}
postsAdapter.notifyDataSetChanged();
}
lastVisible = task.getResult().getDocuments().get(task.getResult().size() - 1);
RecyclerView.OnScrollListener onScrollListener = 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 = UserRef.startAfter(lastVisible).limit(limit);
nextQuery.get().addOnCompleteListener(new OnCompleteListener<QuerySnapshot>() {
@Override
public void onComplete(@NonNull Task<QuerySnapshot> task1) {
if (task1.isSuccessful()) {
for (QueryDocumentSnapshot documentSnapshot : task1.getResult()) {
Log.d(TAG, "Works" + documentSnapshot.getId() + " => " + documentSnapshot.getData());
for (String id : followingList) {
if (documentSnapshot.getId().equals(id)) {
Log.d(TAG, "onComplete: IDS3 :" + id);
FirebaseFirestore db = FirebaseFirestore.getInstance();
CollectionReference PostRef = db.collection("UserPosts")
.document(id)
.collection("Posts");
Query query = PostRef.orderBy("timestamp", Query.Direction.DESCENDING).limit(PostLimit);
query.get().addOnCompleteListener(new OnCompleteListener<QuerySnapshot>() {
@Override
public void onComplete(@NonNull Task<QuerySnapshot> task) {
if (task.isSuccessful()) {
for (QueryDocumentSnapshot documentSnapshot1 : task.getResult()) {
Posts posts = documentSnapshot1.toObject(Posts.class);
postsList.add(posts);
}
}
postsAdapter.notifyDataSetChanged();
}
})
.addOnFailureListener(new OnFailureListener() {
@Override
public void onFailure(@NonNull Exception e) {
Log.d(TAG, "onFailure: Failed to get the posts");
}
});
}
}
}
postsAdapter.notifyDataSetChanged();
Log.d(TAG, "onComplete: resultSize " + task1.getResult().size());
lastVisible = task1.getResult().getDocuments().get(task1.getResult().size() - 1);
if (task1.getResult().size() < limit) {
isLastItemReached = true;
}
}
}
});
}
}
};
post_recycler_view.addOnScrollListener(onScrollListener);
} else {
Log.d(TAG, "Error getting documents: ", task.getException());
}
}
});
}
I tried doing this Query so can i get the last seven days But don't how to query it with paging:
Query query = PostRef.whereLessThan("timestamp",currentTime).whereGreaterThan("timestamp",pastSevenDays);
Started learning about paging recently. So I used this reference to construct this whole method https://stackoverflow.com/a/50742175/4232013. so if anyone can guide me how can i achieve this way of paging would be great thanks!
来源：https://stackoverflow.com/questions/62927499/how-to-use-pagination-to-firestore-query-using-timestamp