Firebase：如果我在 Firestore 集合中查询一条记录并将一列数据传递到 model，我的应用程序是否会对下一个 model 进行第二次查询？

Question

I have a function called getNotifications that queries a collection in Firestore. I am running it on my Notifications screen.

On this screen, I want to optimize the number of Firestore querying to only query once. When the user gets to this screen, the app should query the data once, determine the notifID for the current index, then pass the initial data into the appropriate model. If the notifID == '1' , then the initial data should be transformed via the GroupModel . If the notifID == '2' , then transform via the FriendRequestModel . In doing all this, am I correct in assuming that Firestore will only query once, ie it will not re-query when passing the data through either the GroupModel or the FriendRequestModel ? I'm worried because CommonModel only needs to read the notifID . I'm not even defining any other data fields in it, so I worry that this might signal to the Flutter framework that it needs to re-query.

notifications.dart

class ScreenNotifications extends StatefulWidget {
  const ScreenNotifications({Key? key}) : super(key: key);

  @override
  State<ScreenNotifications> createState() => _ScreenNotificationsState();
}

class _ScreenNotificationsState extends State<ScreenNotifications> {

void initialize() async {
  tempNotifsList = await database.getNotifications();
  setState(() {
    notifsList = tempNotifsList;
  });
}

@override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Notifications'),
      ),
      body: Column(
        children: [
          Expanded(
            child: ListView.builder(
              itemCount: notifsList?.length ?? 0,
              itemBuilder: (context, index) {

                final notif = CommonModel.fromJson(data);
                final notifID = notif.notifID;

                if (notifID == '1') {
                  final group = GroupModel.fromJson(data);
                }

                if (notifID == '2') {
                  final friendRequest = FriendRequestModel.fromJson(data);
                }

              }
              ...//rest of code//

database.dart

Future<List> getNotifications() async {
    final uid = getUID();
    List notifsList = [];
    FirebaseFirestore firestore = FirebaseFirestore.instance;
    CollectionReference notifCollection = firestore.collection('notifications_' + uid);

    final docsRef = await notifCollection.get();
    docsRef.docs.forEach((element) {
      Map<dynamic, dynamic> docMap = {'docID': element.id, 'data': element.data()};
      notifsList.add(docMap);
    });

    return notifsList;
}

Answer 1

the best way to go about this is to the defined a notification type as part of fields while storing your notification,

"nofiType":....//here will be group of friends

so in your ListView.builder then you check if the notif.notiType is equl to the value show the widget