How to have entry variable in a stateful widget?

Question

I'm just beginning to use firestore, and in the same time learning to use flutter and dart. I have two widgets : a stateless one and a stateful one, both returning the age of a user in a collection 'users'. The stateless one has the user id as argument, but cannot handle real time changes. I don't know how to modify the stateful one, which does handle real time changes, so that it takes the user id as argument as well. The stateless one :

class GetAge extends StatelessWidget {
  final String documentId;

  const GetAge(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 const Text("Something went wrong");
        }

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

        if (snapshot.connectionState == ConnectionState.done) {
          Map<String, dynamic> data =
              snapshot.data!.data() as Map<String, dynamic>;
          return Text('Age : ${data['age']} €');
        }

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

The statefull one :

class getAgeRT extends StatefulWidget {
  const getAgeRT({super.key});

  @override
  State<getAgeRT> createState() => _getAgeRTState();
}

class _getAgeRTState extends State<getAgeRT> {
  @override
  Widget build(BuildContext context) {
    return StreamBuilder<DocumentSnapshot<Map<String, dynamic>>>(
        stream: FirebaseFirestore.instance
            .collection('Users')
            .doc('User1')
            .snapshots(),
        builder: (BuildContext context,
            AsyncSnapshot<DocumentSnapshot<Map<String, dynamic>>> snapshot) {
          if (snapshot.hasError) {
            return const Text('Something went wrong');
          }

          if (snapshot.connectionState == ConnectionState.waiting) {
            return const Text("Loading");
          }

          Map<String, dynamic> data =
              snapshot.data!.data() as Map<String, dynamic>;
          return Text(" age :  ${data['age']} ");
        });
  }
}

I tried to copy the stateless one's model to the stateful one but with no success... I don't think it's related to firestore, just a lack of practice from me ! thanks in advance !

Answer 1

The StatefulWidget can receive args too.

class getAgeRT extends StatefulWidget {
  const getAgeRT({required this.documentId, super.key});

  final String documentId;

  @override
  State<getAgeRT> createState() => _getAgeRTState();
}

class _getAgeRTState extends State<getAgeRT> {
  @override
  Widget build(BuildContext context) {
    return StreamBuilder<DocumentSnapshot<Map<String, dynamic>>>(
        stream: FirebaseFirestore.instance
            .collection('Users')
            .doc(widget.documentId)
            .snapshots(),
            ...
}

You can access the args with widget. before