如何从firebase按值获取数据？

Question

How do i call value from firebase when have two child? If value is Guru then go to DashboardGuru if value is Murid then go to DashboardMurid Here Firebase Database i just got null value

Here's my code

 db.getReference().child(FirebaseAuth.getInstance().getCurrentUser().getUid())
                                            .addListenerForSingleValueEvent(new ValueEventListener() {
                                                @Override
                                                public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
                                                    Common.currentUser = dataSnapshot.getValue(Pengguna.class);
                                                    waitingDialog.dismiss();
                                                    String priv = dataSnapshot.child("Guru").getValue().toString();
                                                    if(priv.equals("Guru")){
                                                    startActivity(new Intent(MainActivity.this, DashboardGuru.class));
                                                    finish();
                                                    }
                                                    else{
                                                        startActivity(new Intent(MainActivity.this, DashboardMurid.class));
                                                        finish();
                                                    }
                                                }

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

                                                }
                                            });

Answer 1

I would suggest having one child that holds all the users like

Then when you want to select each by category you:

query = databaseReference.child("users").orderByChild("userID")
                        .equalTo(user.getUid());

                query.addListenerForSingleValueEvent(new ValueEventListener() {
                    @Override
                    public void onDataChange(@NonNull DataSnapshot dataSnapshot) {
                        if(dataSnapshot.exists()){
                            for (DataSnapshot userDetails : dataSnapshot.getChildren()){
                                UserAccount userAccount =userDetails.getValue(UserAccount.class);

                                assert userAccount != null;
                                if(userAccount.userCategory.equals("Fisher Man")){
                                    Intent startActivityForFisherMan = new Intent(LoginActivity.this, FisherManActivity.class);
                                    startActivity(startActivityForFisherMan);
                                    finish();
                                }else{
                                    Intent startActivityForCustomer = new Intent(LoginActivity.this, CustomerMainActivity.class);
                                    startActivity(startActivityForCustomer);
                                    finish();
                                }
                            }

                        }else{
                            Toast.makeText(LoginActivity.this, "Invalid User: Kindly Register", Toast.LENGTH_SHORT).show();
                        }
                    }

Answer 2

dataSnapshot.child("Guru").getValue().toString() searches for a key named " Guru " which does not exist in the JSON under an id of a user. so it returns null value . From the question if the privilege is Guru then go to DashboardGuru activity, if the privilege is Murid goto DashboardMurid. So the updated code should be :

String priv = dataSnapshot.child("privilege").getValue().toString();