firestore_listview.dart

class UserListView extends StatelessWidget {
  UserListView({Key? key}) : super(key: key);

  // live Firestore query
  final usersCollection = FirebaseFirestore.instance.collection('users');

  @override
  Widget build(BuildContext context) => Scaffold(
        appBar: AppBar(title: const Text('Contacts')),
        body: FirestoreListView<Map>(
          query: usersCollection,
          pageSize: 15,
          primary: true,
          padding: const EdgeInsets.all(8),
          itemBuilder: (context, snapshot) {
            final user = snapshot.data();

            return Column(
              children: [
                Row(
                  children: [
                    CircleAvatar(
                      child: Text((user['firstName'] ?? 'Unknown')[0]),
                    ),
                    const SizedBox(width: 8),
                    Column(
                      crossAxisAlignment: CrossAxisAlignment.start,
                      mainAxisAlignment: MainAxisAlignment.center,
                      mainAxisSize: MainAxisSize.min,
                      children: [
                        Text(
                          '${user['firstName'] ?? 'unknown'} '
                          '${user['lastName'] ?? 'unknown'}',
                          style: Theme.of(context).textTheme.subtitle1,
                        ),
                        Text(
                          user['number'] ?? 'unknown',
                          style: Theme.of(context).textTheme.caption,
                        ),
                      ],
                    ),
                  ],
                ),
                const Divider(),
              ],
            );
          },
        ),
      );
}