块 state 未更新

Question

I'm a bit confused as to why the cart counter is not updating when I select multiple items. It just shows 0. I have to switch between tabs to get the counter to change to the correct value.

CartBloc

class CartBloc{

  List<ProductModel> cart = [];
  double totalCartPrice = 0;
  int cartCount = 0;

  final _cartController = StreamController.broadcast();

  Stream get getCartStream => _cartController.stream;

  void addToCart(ProductModel product) {
    cart.add(product);
    cartCount = cartCount + 1;
    totalCartPrice = totalCartPrice + double.parse(product.price);
    _cartController.sink.add(cart);
  }

  void removeFromCart(ProductModel product) {
    cart.remove(product);
    cartCount = cartCount - 1;
    totalCartPrice = totalCartPrice - double.parse(product.price);
    _cartController.sink.add(cart);
  }

 void dispose() {
    _cartController?.close();
  }

}
final cartBloc = CartBloc();

MainScreen

BottomNavyBarItem(
  textAlign: TextAlign.center,
  activeColor: Color(0xFF010101),
  title: Text(' CART',style: TextStyle(
    color:Style.Colors.mainColor,fontSize: 13.0
  )),
  icon: Padding(
    padding: EdgeInsets.only(left:5.0),
    child: Badge(
        badgeColor: Style.Colors.mainColor,
        badgeContent: Text(cartBloc.cartCount.toString(),style: TextStyle(fontWeight: FontWeight.bold),),
        child: Icon(
          SimpleLineIcons.basket,
          size:18.0,
          color:_currentIndex == 1 ? Style.Colors.mainColor:Colors.white
        ),
    )
  )
),

Answer 1

Not sure, since I have never set-up a bloc like this - but as far as I can understand your code you are not changing the state. You always only use _cartController.sink.add(cart); . However, in order to update the ui, the state needs to change. So I always start on an event reaction with an InProgressState before I update the data with an DisplayDataState .

Anyways, maybe it is easier to use the bloc and the bloc_provider package and work with mapEventToState