How do I read data from the Flutter Firebase Real-Time Database?

Question

I've used the Real-Time Database with this setup:

->users
->uid
    ->name
    ->email
    ->other info

If I wanted to save the user data I would use my User class and then set the object in the database like this:

final FirebaseUser user = await FirebaseAuth.instance.currentUser(); FirebaseDatabase.instance.reference().child("kullanıcılar").child(user.uid).child("takip").set({"uid":"uid"});

I tried it and it works fine.

But how can I retrieve these values from the database? For instance, once I set a User object as shown above, I may want to retrieve the user's email. I don't mean getting the email through the sign-in provider. I want the email through the real-time database. I've tried working this out for a while now but the documentation isn't helping much. All it shows is to setup listeners in order to wait for changes to the data. But I'm not waiting for changes, I don't want a listener. I want to directly get the values in the database by using the keys in the JSON tree. Is this possible via the real-time database? If so, how can it be done because either the documentation doesn't explain it or I'm just not understanding it.Thanks.

Answer 1

You can retrieve the value once using .once(). Here's an example: https://github.com/flutter/plugins/blob/master/packages/firebase_database/example/lib/main.dart#L62

or better, with async/await:

Future<String> getEmail() async {
  String result = (await FirebaseDatabase.instance.reference().child("path/to/user/record/email").once()).value;
  print(result);
  return result;
}

Answer 2

You can't retrieve the single value from firebase, it always return the DocumentSnapshot of the whole record. You can get a single record from user table by using user id like this:

getData() async {
  final FirebaseUser user = await _firebaseAuth.currentUser();
  return await FirebaseDatabase.instance.reference().child('user').equalTo(user.uid);
}

Get it like this:

getData().then((val){
    print(val.email);
});