Filter Stream to List - flutter

Question

I have the following stream builder:
streamCard() {
return StreamBuilder(
stream: cardsRef
.orderBy("timestamp", descending: true)
.limit(10)
.snapshots(),
builder: (context, snapshot) {
if (!snapshot.hasData) {
return circularProgress();
}
List<CustomCard> cards = [];
snapshot.data.documents.forEach((doc) {
cards.add(CustomCard.fromDocument(doc));
});
...
return Stack(
alignment: Alignment.center,
children: cards,
);
I need to filter certain cards from being added to the stream/displayed when:
I'm the owner of the card ('ownerId' == currentUserId)
I've liked the card ('liked.' contains = currentUserId)
OwnerId is a field inside each document and Liked is an array with Id's who have liked it.
I've tried to remove the cards from being added to the cards List<> with .where and .contains, but couldn't properly 'discard' them. I was thinking another option could be to modify the Stack directly, in
children: cards
with cards.removeWhere/.skip, or something like that.

Answer 1

To follow the bloc pattern, business logic should happen in your bloc class. Which mean that you should do all the sorting or filtering in the bloc. When you add a new object into sink, the streambuilder will rebuild.
class BlaBloc {
final BehaviorSubject<List<String>> _results =
BehaviorSubject<List<String>>();
getResults() {
List<String> yourresults = yourapi.getResults();
_results.sink.add(yourresults);
};
getResultsLikedByMe() {
List<String> yourresults = yourapi.getResultsLikedByMe();
_results.sink.add(yourresults);
}
getResultsOwnerIsMe() {
List<String> yourresults = yourapi.getResultsOwnerIsMe();
_results.sink.add(yourresults);
}
BehaviorSubject<List<String>> get results => _results;
}
final blaBloc = BlaBloc();
When you build your streambuilder, point to your Bloc, for example as below:
body: StreamBuilder<List<String>>(
stream: blaBloc.results,
builder: (context, AsyncSnapshot<RecipesResponse> snapshot) {
// build your list here...
}
)
To understand more about Bloc pattern, this is a very useful tutorial you could follow here: RxDart Bloc Pattern