flutter data not retrieved from firestore when using stream - flutter

Question

DatabaseService databaseService = new DatabaseService();
Stream questionsSnapshot;
so Im using a stream and and a database service to retrieve data (questions and answers of a quiz) to my listView builder
the called function from database service is
getAquizData(String quizId) async{
return await Firestore.instance
.collection("quiz")
.document(quizId)
.collection("questionReponses")
.snapshots();
}
the init state function
#override
void initState() {
databaseService.getAquizData(widget.quizId).then((value){
questionsSnapshot = value;
setState(() {});
});
super.initState();
}
my listViewBuilder
#override
Widget build(BuildContext context) {
return Scaffold(
// an appbar
) ,
body: Container(
child: Column(children: <Widget>[
StreamBuilder(
stream: questionsSnapshot,
builder: (context, snapshot) {
return snapshot.data == null
? Container(child: Text("empty"),) : ListView.builder(
shrinkWrap: true,
physics: ClampingScrollPhysics(),
itemCount: snapshot.data.documents.length,
itemBuilder: (context,index){
return QuizPlayTile(
questionModel: getQuestionModelFromDatasnapshot(
snapshot.data.documents[index]),
index: index,
);
});
},
)
],)
)
);
}
}
when running it just show the word empty for a second and then it shows questions without answers
[1]: https://i.stack.imgur.com/E4CS4.jpg

Answer 1

We can use stream builder without calling it in initState method. Following code works for me. user quizStreamer in build method.
quizStreamer(){
return StreamBuilder(
stream: Firestore.instance
.collection('quiz')
.document(quizId)
.collection('questionReponses')
.snapshots(),
builder: (context, AsyncSnapshot<QuerySnapshot> snapshot) {
//loadWidgets method takes snapshot and render defined widgets
return loadWidgets(snapshot);
},
);
}