如何创建 Flutter stream 构建器？

Question

I have an "updateDatabase" function that retrieves the data from the Firebase Real-Time Database and saves it in the shared preferences... I put this function in the Init State of my home page but I would like this to become a stream builder这样就不必每次都重新打开页面来获取更新的数据，而是立即拥有它们。

这是我的更新数据库 function 的一部分：

updateDatabase() async {
  final prefs = await SharedPreferences.getInstance();

  DatabaseReference starCountRef =
      FirebaseDatabase.instance.ref('/utenti/$uid/');
  starCountRef.onValue.listen((DatabaseEvent event) {
    final data = event.snapshot.value as Map;
    prefs.setInt("videoAgosto2022", data["videoAgosto2022"]);
ect...
}

这是我主页的一部分...

小部件构建（BuildContext context）{ double altezza = MediaQuery.of(context).size.height;

  return StreamBuilder(
        stream: What should I put here?,
        builder: (context, snapshot) => SingleChildScrollView(
              child: Center(
                child: Column(
                  mainAxisAlignment: MainAxisAlignment.center,
                  mainAxisSize: MainAxisSize.min,
                  children: <Widget>[
                    Column(

我应该在“dada”字段中输入什么？

Answer 1

A stream function 必须标记为async*

然后，您只需将 function 放入StreamBuilder小部件的stream属性中