如何从Firebase中删除一个子节点而不删除所有子节点

Question

I need to remove a child node from firebase on a button click but when I use .RemoveValue() it deletes all the child nodes not just one.

 LeaderClass leader = new LeaderClass((uploadCurrent.getName()).trim(),
                        (uploadCurrent.getCategory()).trim(),(Integer.toString(mCountLikes )));
                mDatabaseLike.removeValue();

The full code is below:

    //Count Likes functionality
    mDatabaseRef.child((uploadCurrent.getName())).addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(@NonNull DataSnapshot dataSnapshot) {

            if(dataSnapshot.exists())
            {
                //Counting likes in 'Likes' database by counting children
                mCountLikes = (int) dataSnapshot.getChildrenCount();
                holder.mCountbtn.setText(Integer.toString(mCountLikes ) + " Likes" );


               LeaderClass leader = new LeaderClass((uploadCurrent.getName()).trim(),
                     (uploadCurrent.getCategory()).trim(),(Integer.toString(mCountLikes )));

              mDatabaseLike.push().setValue(leader);




            }
            else{
                holder.mCountbtn.setText("0 Likes");

                LeaderClass leader = new LeaderClass((uploadCurrent.getName()).trim(),
                        (uploadCurrent.getCategory()).trim(),(Integer.toString(mCountLikes )));
                mDatabaseLike.removeValue();


            }
        }

        @Override
        public void onCancelled(@NonNull DatabaseError databaseError) {

        }
    });

Here is my firebase structure:

CountLikes: {
   "-LXBQRbkiL3fZUnRedrB": {
      category: "Technology"
      name: "Project 467"
      vote: "1"
   }

Answer 1

When you call removeValue on a DatabaseReference Firebase removes all data at that reference. It looks like your mDatabaseLike points to CountLikes , so calling mDatabaseLike.removeValue() removes all data under that location.

To remove a single child node, you'll need to know the key of the like to remove, ie the -LXBQRbkiL3fZUnRedrB in the JSON you shared.

When you know that, removing just that one child node is as simple as:

mDatabaseLike.child("-LXBQRbkiL3fZUnRedrB").removeValue();