logged in User Flutter return null ( data from Firebase )

Question

I made Flutter project, and I want to show the name of logged in user, but the code (the yellow highlight)( https://i.stack.imgur.com/E2mU1.jpg ) return null, the result be like "Name: + null" please help

I want to show the name of logged in user from the firebase

Answer 1

Use FutureBuilder, Example -

class GetUserName extends StatelessWidget {
  final String documentId;

  GetUserName(this.documentId);

  @override
  Widget build(BuildContext context) {
    CollectionReference users = FirebaseFirestore.instance.collection('users');

    return FutureBuilder<DocumentSnapshot>(
      future: users.doc(documentId).get(),
      builder:
          (BuildContext context, AsyncSnapshot<DocumentSnapshot> snapshot) {

        if (snapshot.hasError) {
          return Text("Something went wrong");
        }

        if (snapshot.hasData && !snapshot.data!.exists) {
          return Text("Document does not exist");
        }

        if (snapshot.connectionState == ConnectionState.done) {
          Map<String, dynamic> data = snapshot.data!.data() as Map<String, dynamic>;
          return Text("Full Name: ${data['full_name']} ${data['last_name']}");
        }

        return Text("loading");
      },
    );
  }
}

https://firebase.flutter.dev/docs/firestore/usage