Firebase返回空值

Question

This is the structure:

I wanna select the company, phone and city where the email = current email of the connected user.

This is my code:

DatabaseReference mDatabases = FirebaseDatabase.getInstance().getReference();

Query query = mDatabases.child("Users").orderByChild("email").equalTo(FirebaseAuth.getInstance().getCurrentUser().getEmail().toString());

query.addListenerForSingleValueEvent(new ValueEventListener() {
    @Override
    public void onDataChange(DataSnapshot dataSnapshot) {
        if (dataSnapshot.exists()) {


            User user =  dataSnapshot.getValue(User.class);
            String company = user.getCompany();
            String city = user.getCity);
        }
    }

    @Override
    public void onCancelled(DatabaseError databaseError) {

    }
});

The returned result is null.

When i change dataSnapshot.getValue(User.class) to dataSnapshot.getValue() , it return all values of the node.

Answer 1

You haven't indicated which user you want to retrieve. As your dataSnapshot returns a list of user values (even the list has only 1 element), you have to specify which user you want to get:

User user =  dataSnapshot.child(userId).getValue(User.class);

Replace userId to the id of the user you want to retrieve (current user I guess!)