// Filter out the already existing products inside Products list public async Task FilterProductsAsync(bool refreshProductsList) { List <Product> products = await OnlineDataManager.FilterProductsByCategoryLocationAsync(this.CategoryList, GetCurrencyString()); // Order by Date products = products.OrderByDescending(p => p.Date).ToList(); this.Products = new ObservableCollection <Product>(products); if (refreshProductsList) { ProductPage.UpdateProductListItemSource(); } }