Need get the count of likes

Question

I can't get done the count of likes. The users can like a post and I want Firebase count how many likes post gets from users.

My code:

viewHolder.mThumb.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View view) {
    mProcessLikes = true;
    mDatabaseLikes.addValueEventListener(new ValueEventListener() {
       @Override
       public void onDataChange(DataSnapshot dataSnapshot) {
       if (mProcessLikes){
          if (dataSnapshot.child(post_key).hasChild(mAuth.getCurrentUser().getUid())){                                            mDatabaseLikes.child(post_key).child(mAuth.getCurrentUser().getUid()).removeValue();
          mProcessLikes = false;
          } else {mDatabaseLikes.child(post_key).child(mAuth.getCurrentUser().getUid()).setValue("like");
          mProcessLikes = false;
          }
       }
    }
    @Override
    public void onCancelled(DatabaseError databaseError) {}
    });
  }
});

What code should I add in the code above to achieve the result is showed on attached image?

Combining the likes and the like counts like this is a bad idea. I'd use separate nodes for these, e.g. `/Likes/$postid/$uid` and `LikeCounts/$postid`. — Frank van Puffelen, Dec 09 '16 at 10:06
Firebase has recently released Cloud Functions. Have a look at this [answer](http://stackoverflow.com/a/42713792/5861618) for more details — Rosário Pereira Fernandes, Mar 10 '17 at 08:57

score 1 · Answer 1 · answered Dec 09 '16 at 10:11

Remove the count field from you table. If I understand correctly.. When an object is being liked, some user id is being added. This works and is sufficient. Query your like count as followed:

databaseRef.child("Likes").child(*key*).addListenerForSingleValueEvent(new ValueEventListener() {

      @Override
      public void onDataChange (DataSnapshot dataSnapshot) {
        dataSnapshot.getChildrenCount(); <- like count
      }

      @Override
      public void onCancelled (DatabaseError databaseError) {

      }
    });

Brilliant!! getChildrenCount suits perfect! Thanx! – Ya Si Dec 09 '16 at 13:10 — Ya Si, Dec 09 '16 at 13:10

score 0 · Answer 2 · answered Dec 09 '16 at 08:14

You should read about Save data as transactions from the Firebase Documentation,

For example :

private void onStarClicked(DatabaseReference postRef) {
    postRef.runTransaction(new Transaction.Handler() {
        @Override
        public Transaction.Result doTransaction(MutableData mutableData) {
            Post p = mutableData.getValue(Post.class);
            if (p == null) {
                return Transaction.success(mutableData);
            }

            if (p.stars.containsKey(getUid())) {
                // Unstar the post and remove self from stars
                p.starCount = p.starCount - 1;
                p.stars.remove(getUid());
            } else {
                // Star the post and add self to stars
                p.starCount = p.starCount + 1;
                p.stars.put(getUid(), true);
            }

            // Set value and report transaction success
            mutableData.setValue(p);
            return Transaction.success(mutableData);
        }

        @Override
        public void onComplete(DatabaseError databaseError, boolean b,
                               DataSnapshot dataSnapshot) {
            // Transaction completed
            Log.d(TAG, "postTransaction:onComplete:" + databaseError);
        }
    });
}

Full example here

Need get the count of likes

2 Answers2