Retrieve Current User's Data (user_id) Firebase?

问题

        firebaseAuth = FirebaseAuth.getInstance();
        mDatabase = FirebaseDatabase.getInstance();
        mDb = mDatabase.getReference();
        FirebaseUser user = firebaseAuth.getCurrentUser();
        userKey = user.getUid();

        mDb.child(userKey).addValueEventListener(new ValueEventListener() {
            @Override
            public void onDataChange(DataSnapshot dataSnapshot) {
                Log.d(TAG, "Name: " + dataSnapshot.child("user_id").getValue());

                userID = String.valueOf(dataSnapshot.child("user_id").getValue());
            }

            @Override
            public void onCancelled(DatabaseError databaseError) {

            }
        });

I do not know what is wrong with my code, I want to retrieve value of user id.

回答1:

To solve this, please use the following code:

firebaseAuth = FirebaseAuth.getInstance();
mDatabase = FirebaseDatabase.getInstance();
mDb = mDatabase.getReference();
FirebaseUser user = firebaseAuth.getCurrentUser();
userKey = user.getUid();

mDb.child("Tunanetra").child(userKey).addValueEventListener(new ValueEventListener() {
    @Override
    public void onDataChange(DataSnapshot dataSnapshot) {
        String userID = dataSnapshot.child("user_id").getValue(String.class);
        Log.d(TAG, "Name: " + userID);
    }

    @Override
    public void onCancelled(DatabaseError databaseError) {}
});

With this code, you'll be able to print out in the logcat, the id of the users that is authenticated and exists under Tunanetra node. If the user exists under the Orangtua node, then just change Tunanetra with Orangtua.

回答2:

I think instead of

mDb = mDatabase.getReference(); 

you should be using

mDb = mDatabase.getReference("Tunanetra");

because that's where the user you're looking for is nested at.

回答3:

It's simple. If you want to retrieve user data. Then you have to first select the child node in which you want to look for the user.

You have to Nodes Tunanetra and Orangtua

Else you can try this order by approach.

FirebaseAuth firebaseAuth = FirebaseAuth.getInstance();
        FirebaseDatabase mDatabase = FirebaseDatabase.getInstance();
        DatabaseReference mDb = mDatabase.getReference();
        FirebaseUser user = firebaseAuth.getCurrentUser();
        String userKey = user.getUid();

        //First Approach
        mDb.child("Tunanetra").child(userKey).addValueEventListener(new ValueEventListener() {
            @Override
            public void onDataChange(DataSnapshot dataSnapshot) {
                String userID = String.valueOf(dataSnapshot.child("user_id").getValue());
            }

            @Override
            public void onCancelled(DatabaseError databaseError) {

            }
        });

        //Second Approach
        mDb.child("Tunanetra").orderByChild("email").equalTo(user.getEmail()).limitToFirst(1).addValueEventListener(new ValueEventListener() {
            @Override
            public void onDataChange(DataSnapshot dataSnapshot) {

                if(dataSnapshot.getChildrenCount()>0){
                    for(DataSnapshot data : dataSnapshot.getChildren()){
                        String userID = String.valueOf(data.child("user_id").getValue());
                    }
                }
            }

            @Override
            public void onCancelled(DatabaseError databaseError) {

            }
        });

来源：https://stackoverflow.com/questions/49409468/retrieve-current-users-data-user-id-firebase