How to filter a list of obseravble in rxdart

问题

I am trying to implement bloc pattern in rxdart . I am trying to build todo app type of app . I implemented showing all items in list but what I want is not to show completed and uncompleted items in different part . However I am not able to filter the items based on completed on rxdart .

import 'package:rxdart/rxdart.dart';
import '../models/ShoppingItem.dart';
class ShoppingItemBloc {
  final _shoppingItems = BehaviorSubject<List<ShoppingItem>> 
(seedValue: []);

Observable<List<ShoppingItem>> get allShoppingItems => 
_shoppingItems.stream;

 //Getter to implement
 Observable<List<ShoppingItem>> get completedShoppingItems =>

 dispose() {
  _shoppingItems.close();
 }
}

What I wanted is to get the completed shoppingItems . The class ShoppingItem has a boolean property completed . I wanted to filter it on that basis .

Any help would be appricated thanks

回答1:

you can use where on the stream to filter out as per your need. Since you are observing list of item you need to map before filtering individual item. In our case it would be something like this.

 Observable<List<ShoppingItem>> get completedShoppingItems => 
    _shoppingItems.stream.map((itemList) =>
        itemList.where((item) => item.completed));

来源：https://stackoverflow.com/questions/54500308/how-to-filter-a-list-of-obseravble-in-rxdart