Find if child inside child data is exist or not Android Firebase

Question

This may be duplicate Question but i have tries alot but i didnt get my result, Here is my firebase structure

Updated

I need to fin

Answer 1

As AlexMamo said you need to restructure database, i.e to flatten two levels hierarchy to only one level. As shown below:

Expense_Month
   |
   --- November_2018
          |
          --- 3_-LQ ... Gb
          |     |
          |     --- expensesName: "gross"
          |     |
          |     --- total: 66
          |     |
          |     --- day: "Monday"
          |     |
          |     --- day: 3
          |
          --- 4_-LQ ... LO
                |
                --- expensesName: "oil"
                |
                --- total: 33
                |
                --- day: "Tuesday"
                |
                --- day: 4

Notice each node in November_2018 is organised by the key formed by day followed by push Id separated by underscore. i.e "day_pushId". You can also add additional field for day (incase for particular day query is required). Then the query can be formed in the similar fashion as for "expensesName":

//Here monthyr is the November_2018
          expensesaddref = databaseReference.child(username).child("Expense_Month").child(monthyr);
expensesaddref.orderByChild("expensesName").equalTo("oil").addListenerForSingleValueEvent(new ValueEventListener() {
            @Override
            public void onDataChange(@NonNull DataSnapshot dataSnapshot) {

                if(dataSnapshot.getChildrenCount() > 0){
                    Toast.makeText(getContext(), "Exist", Toast.LENGTH_SHORT).show();

                }else
                    Toast.makeText(getContext(), "not", Toast.LENGTH_SHORT).show();
            }

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

            }
        });