Complex query on Firebase for Android

Question

I have got data structure like below. I need to a query for FirebaseRecyclerAdapter like this;

 Query query = dbPosts.orderByChild("createDate").orderByChild("status").equlTo(0).orderByChild("voteSum").biggerThan(20);

I want to sort by the date of creation first, then sort by a specific situation, and finally, bring those who follow a certain situation.

I know there are not such as specifications but I think, you are understand what I mean it. So how can I do like this query or how can I do it in other ways to show my wishes to RecyclerView.

ps: Sorry for my poor English.

Data Structure

"posts" : {
"-K_FaI8rsasB0hvFNTTv" : {
  "category" : 0, -> int
  "createdDate" : 1483115934775,
  "image" : "https://firebasestorage.googleapis.com/...",
  "status" : 0, -> int
  "title" : "sadfsadfsadf",
  "userId" : "iuHJQ044GrMPjRMF1CxPq15tp6g2",
  "username" : "someone",
  "voteSum" : 34 -> Long
},
"-K_GI57zSiPP6ETgctPD" : {
  "category" : 0, -> int
  "createdDate" : 1483127677924,
  "image" : "https://firebasestorage.googleapis.com/...",
  "status" : 0, ->int
  "title" : "qwewqeqwe",
  "userId" : "MWv568D0f3VO1y683kZumOQ7gHZ2",
  "username" : "idiots",
  "voteSum" : 13 -> Long
}

}

FirebaseRecyclerAdapter:

public FirebaseRecyclerAdapter recyclerAdapter(Query query) {

    FirebaseRecyclerAdapter<Post, PostViewHolder> firebaseRecyclerAdapter = new FirebaseRecyclerAdapter<Post, PostViewHolder>(
            Post.class,
            R.layout.card_view_post,
            PostViewHolder.class,
            query
    ) {
        @Override
        protected void populateViewHolder(final PostViewHolder viewHolder, Post model, int position) {

            final String postId = getRef(position).getKey();
            // TODO sum vote
            viewHolder.setTitle(model.getTitle());
            viewHolder.setImage(getContext(), model.getImage());
            viewHolder.setSumVotes(postId);
            viewHolder.setSumComments(postId);
            if (checkAuthUser()) {
                viewHolder.setUpVote(postId);
                viewHolder.setDownVote(postId);
            }

            viewHolder.txtTitle.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View view) {
                    Intent intent = new Intent(getActivity(), SinglePostActivity.class);
                    intent.putExtra(Enums.PostKeys.postId.getValue(), postId);
                    startActivity(intent);
                }
            });

            viewHolder.imvImage.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View view) {
                    Intent intent = new Intent(getActivity(), SinglePostActivity.class);
                    intent.putExtra(Enums.PostKeys.postId.getValue(), postId);
                    startActivity(intent);
                }
            });

            viewHolder.imbComment.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View view) {
                    Intent intent = new Intent(getActivity(), CommentsActivity.class);
                    intent.putExtra(Enums.PostKeys.postId.getValue(), postId);
                    startActivity(intent);
                }
            });


            viewHolder.imbUpVote.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View view) {

                    if (!checkAuthUser()) {
                        startActivity(new Intent(getActivity(), SignUpActivity.class));
                        return;
                    }
                    processVote = true;

                    Singleton.getDbPostDownVote().child(postId).addValueEventListener(new ValueEventListener() {
                        @Override
                        public void onDataChange(DataSnapshot dataSnapshot) {
                            if (processVote == true) {
                                if (dataSnapshot.hasChild(getUserId())) {
                                    Singleton.getDbPostDownVote().child(postId).child(getUserId()).removeValue();
                                }
                            }
                        }

                        @Override
                        public void onCancelled(DatabaseError databaseError) {

                        }
                    });

                    Singleton.getDbPostUpVote().child(postId).addValueEventListener(new ValueEventListener() {
                        @Override
                        public void onDataChange(DataSnapshot dataSnapshot) {


                            if (processVote == true) {
                                if (dataSnapshot.hasChild(getUserId())) {
                                    Singleton.getDbPostUpVote().child(postId).child(getUserId()).removeValue();
                                    processVote = false;
                                } else {
                                    Singleton.getDbPostUpVote().child(postId).child(getUserId()).setValue(0);
                                    processVote = false;
                                }
                            }
                        }

                        @Override
                        public void onCancelled(DatabaseError databaseError) {

                        }
                    });

                }
            });

            viewHolder.imbDownVote.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View view) {

                    if (!checkAuthUser()) {
                        startActivity(new Intent(getActivity(), SignUpActivity.class));
                        return;
                    }

                    processVote = true;

                    Singleton.getDbPostUpVote().child(postId).addValueEventListener(new ValueEventListener() {
                        @Override
                        public void onDataChange(DataSnapshot dataSnapshot) {
                            if (processVote == true) {
                                if (dataSnapshot.hasChild(getUserId())) {
                                    Singleton.getDbPostUpVote().child(postId).child(getUserId()).removeValue();
                                }
                            }
                        }

                        @Override
                        public void onCancelled(DatabaseError databaseError) {

                        }
                    });

                    Singleton.getDbPostDownVote().child(postId).addValueEventListener(new ValueEventListener() {
                        @Override
                        public void onDataChange(DataSnapshot dataSnapshot) {

                            if (processVote == true) {

                                if (dataSnapshot.hasChild(getUserId())) {
                                    Singleton.getDbPostDownVote().child(postId).child(getUserId()).removeValue();
                                    processVote = false;
                                } else {
                                    Singleton.getDbPostDownVote().child(postId).child(getUserId()).setValue(1);
                                    processVote = false;
                                }
                            }
                        }

                        @Override
                        public void onCancelled(DatabaseError databaseError) {

                        }
                    });

                }
            });


            viewHolder.imbMenu.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    Context context = new ContextThemeWrapper(getContext(), R.style.popupMenuStyle);
                    PopupMenu popup = new PopupMenu(context, viewHolder.imbMenu);
                    //inflating menu from xml resource
                    popup.inflate(R.menu.post_menu);
                    //adding click listener
                    popup.setOnMenuItemClickListener(new PopupMenu.OnMenuItemClickListener() {
                        @Override
                        public boolean onMenuItemClick(MenuItem item) {
                            switch (item.getItemId()) {
                                case R.id.deletePost:
                                    break;
                                case R.id.reportPost:

                                    break;
                            }
                            return false;
                        }
                    });
                    //displaying the popup
                    popup.show();
                }
            });

        }


    };

    return firebaseRecyclerAdapter;
}

Answer 1

First read my previous answer on the same topic: Query based on multiple where clauses in firebase .

You have a variation of that. You can combine the status and voteSum values in a single property and then perform the createdDate sorting client-side.

"posts" : {
    "-K_FaI8rsasB0hvFNTTv" : {
      "status_voteSum": "0_34",
      "category" : 0,
      "createdDate" : 1483115934775,
      "image" : "https://firebasestorage.googleapis.com/...",
      "status" : 0,
      "title" : "sadfsadfsadf",
      "userId" : "iuHJQ044GrMPjRMF1CxPq15tp6g2",
      "username" : "someone",
      "voteSum" : 34
    },
    "-K_GI57zSiPP6ETgctPD" : {
      "status_voteSum": "0_13",
      "category" : 0,
      "createdDate" : 1483127677924,
      "image" : "https://firebasestorage.googleapis.com/...",
      "status" : 0,
      "title" : "qwewqeqwe",
      "userId" : "MWv568D0f3VO1y683kZumOQ7gHZ2",
      "username" : "idiots",
      "voteSum" : 13
    }
}

Now you can query for all items with status=0 and voteSum>20 with:

ref.orderByChild("status_voteSum").startAt("0_21")...

You'll still need to find a way to re-order the items on createdDate client-side, since the approach can only be used for one relation operation (the value at the end).

In addition to the answer I linked, this approach is also covered in one of the episodes of our video series Firebase for SQL developers .