How to make a Sink to format the result of a Stream?

Posted by Pinki | Updated on May 3, 2020

Want to make a Sink to format the result of a Stream? Use the combineLatest function from the rxdart package. It takes the latest values of input streams, so any time either the locale or cart items change it will calculate and format the total cost.

import 'dart:async'; // Sink, Stream

import 'dart:ui'; // Locale

import 'package:rxdart/rxdart.dart'; // Observable, *Subject

class Bloc {

var _locale = BehaviorSubject<Locale>(seedValue: Locale('en', 'US'));

var _items = BehaviorSubject<List<CartItem>>(seedValue: []);

Stream<String> _totalCost;

Sink<Locale> get locale => _locale.sink;

Stream<List<CartItem>> get items => _items.stream;

Stream<String> get totalCost => _totalCost;

Bloc() {

_totalCost = Observable.combineLatest2<Locale, List<CartItem>, String>(

_locale, _items, (locale, items) {

// TODO calculate total price of items and format based on locale

return 'USD 10.00';

}).asBroadcastStream();

}

void dispose() {

_locale.close();

_items.close();

}

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How to make a Sink to format the result of a Stream?

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