retrieve data currentuser. from firebase return null

问题

Hello I'm trying to retrieve the data from a realtime firebase field but it returns null. I checked with textView52.setText (firebaseUser.getEmail ()); to see if it was really connected and it works. the problem is in recovering a value from the database which in this case is the field "name" could someone help me? am i doing something wrong? any help is welcome.

    DatabaseReference ref = FirebaseDatabase.getInstance().getReference("Users");
    ref.child("Users").addListenerForSingleValueEvent(new ValueEventListener() {
        FirebaseUser user = FirebaseAuth.getInstance().getCurrentUser();
        String userUid = user.getUid();
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            String data = dataSnapshot.child("name").getValue(String.class);
            textView52.setText(data);
        }

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

        }
    });

}

回答1:

try

FirebaseUser user = FirebaseAuth.getInstance().getCurrentUser();
String userUid = user.getUid();
DatabaseReference ref = FirebaseDatabase.getInstance().getReference();
ref.child("Users").child(userUid).addListenerForSingleValueEvent(new ValueEventListener() {

    @Override
    public void onDataChange(DataSnapshot dataSnapshot) {
        String data = dataSnapshot.child("name").getValue();
        textView52.setText(data);
    }

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

    }
});}

回答2:

UPDATED! check those lines

DatabaseReference ref = FirebaseDatabase.getInstance().getReference("Users");
ref.child("Users").addListenerForSingleValueEvent(new ValueEventListener() {...}

Basically you try to call in Users another child called User, to understand very easy, replace the of that user here

ref.child("use_that_key_here").addListenerForSingleValueEvent(new ValueEventListener() {...}

Is not a solution, you cannot hard code every key, but with this you should see the data

try something like that:

// ref to db
DatabaseReference ref= FirebaseDatabase.getInstance();
ref.child("Users").addListenerForSingleValueEvent(new ValueEventListener() {
    @Override
    public void onDataChange(DataSnapshot dataSnapshot) {
       //debug this par and check if you can see your user
    }

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

    }
});

来源：https://stackoverflow.com/questions/60050114/retrieve-data-currentuser-from-firebase-return-null

标签

android

firebase

firebase-realtime-database