Multiuser application using flutter - dart

Question

I am working on one application which has multiple users. I have a list of resources, this list of resources are like a list of chocolates (only one and unique). Now, I am showing this chocolates on the home screen of all active users. Now, user can click on chocolate and it will be given to them. But, when this happens i want to refresh all logged in users so to ensure that no two users are having same chocolate.
I am using database trigger to monitor the change in DB. I am able to do that but my concern is how to refresh listView.
My Algorithm is as below:
1) Monitor changes in Database.
2) Get Fresh set of data.
3) Update View
I tried creating syncDatabaseFunction as below:
Future syncDatabaseFunction() async {
CollectionReference reference = Firestore.instance.collection('Chocolates');
reference.snapshots().listen((querySnapshot){
querySnapshot.documentChanges.forEach((change){
print("Changed Chocolate");
BackendOperations.getAllChocolates().then((value){
var chocolateTemp = (value as List<ChocolateModel>)
.where((element) => (element.chocolateColor == "Brown"))
.toList();
print("Count is ");
return chocolateTemp;
});
});
});
}
For listview I am using futureBuilder.

Answer 1

I think that if you use StreamBuilder you will solve the problem.
When a user remove or add a new Comment it show for all users.
StreamBuilder was made to do this, be a Observer of the Stream.
This is my code:
Widget getListComment() {
return StreamBuilder<QuerySnapshot>(
stream: Firestore.instance
.collection('comments')
.where('post', isEqualTo: postRef)
.orderBy('createdAt', descending: true)
.snapshots(),
builder: (BuildContext context, AsyncSnapshot<QuerySnapshot> snapshot) {
if (snapshot.hasError) return new Text('Error: ${snapshot.error}');
switch (snapshot.connectionState) {
case ConnectionState.waiting:
return Column(
children: <Widget>[
CircularProgressIndicator(),
],
);
default:
return new ListView(
children:
snapshot.data.documents.map((DocumentSnapshot document) {
return CommentItem(
key: Key(document.documentID),
comment: Comment.fromDoc(document),
myUser: widget.myUser,
);
}).toList(),
);
}
},
);
}
I receive comments from Firebase and show in a ListView, I think that is like your chocolates.