Question

我正在尝试检索当前用户的CircleMembers下加入的电话号码，但datasnapshot返回null。请帮帮我。哪种方法是检索mycircle下成员的正确方法？谢谢你。

我的firebase数据库在下面

这是我的代码。

 
   userReference = FirebaseDatabase.getInstance().getReference().child( "Users" );
       databaseReference = FirebaseDatabase.getInstance().getReference().child( "Users").child( user.getUid() ).child( "CircleMembers" );
     databaseReference.addListenerForSingleValueEvent( new ValueEventListener() {
            @Override
            public void onDataChange(@NonNull DataSnapshot dataSnapshot) {

            nameList.clear();

            if(dataSnapshot.exists()){
                for(DataSnapshot  dss:dataSnapshot.getChildren()){
                    String circlememberID = dss.child( "CircleMembers" ).getValue(String.class);
                    userReference.child( circlememberID )
                            .addListenerForSingleValueEvent( new ValueEventListener() {
                                @Override
                                public void onDataChange(@NonNull DataSnapshot dataSnapshot) {


                                    phone = dataSnapshot.getValue( Phone.class );
                                    //fetching phone numbers under Circlemembers (to which circle current user is joined)
                                    nameList.add( phone);
                                    adapter.notifyDataSetChanged();
                                }

                                @Override
                                public void onCancelled(@NonNull DatabaseError databaseError) {
                                    Toast.makeText( getApplicationContext(), databaseError.getMessage(), Toast.LENGTH_SHORT ).show();
                                }
                            } );

                    adapter = new MembersAdaptor(nameList,getApplicationContext());
                    recyclerView.setAdapter( adapter );
                    adapter.notifyDataSetChanged();

                }

            }
            else{
                Toast.makeText( getApplicationContext(), "No circle", Toast.LENGTH_SHORT ).show();
            }

        }

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

        }
    } );

Answer 1

进行试用。我认为这是代码应遵循的方式：

ObjectMapper objectMapper = new ObjectMapper();

Answer 2

要获取CircleMemebers节点下存在的所有电话号码，请使用以下代码：

String phoneNo = FirebaseAuth.getInstance().getCurrentUser().getPhoneNumber();
DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
DatabaseReference circleMemebersRef = rootRef.child("Users").child(phoneNo).child("CircleMemebers");
ValueEventListener valueEventListener = new ValueEventListener() {
    @Override
    public void onDataChange(DataSnapshot dataSnapshot) {
        for(DataSnapshot ds : dataSnapshot.getChildren()) {
            String phoneNumber = ds.getValue(String.class);
            Log.d(TAG, phoneNumber);
        }
    }

    @Override
    public void onCancelled(@NonNull DatabaseError databaseError) {
        Log.d(TAG, databaseError.getMessage());
    }
};
circleMemebersRef.addListenerForSingleValueEvent(valueEventListener);

您的logcat中的输出将是：

+919212143422
+615325453454

如何从Android中的Firebase中从特定节点检索数据

2 个答案: