//Работа с заглушкой картинки:
<Page.Resources>
        <BitmapImage x:Key="defaultImage" UriSource="/image/picture.png"/>
    </Page.Resources>
<Image Width="100" Height="100" Source="{Binding ProductPhoto, TargetNullValue={StaticResource defaultImage}}"/>
//Поиск, фильтрация, сортировка:
void Filter()
        {
            List<Product> product = new List<Product>();
            product = ClassDBase.DB.Product.ToList();

            //Поиск по названию
            if (!string.IsNullOrWhiteSpace(SearchName.Text))  // Проверка пустую запись и запись состоящую из пробелов
            {
                product = product.Where(x => x.ProductName.ToLower().Contains(SearchName.Text.ToLower())).ToList();
                if (product.Count == 0)
                {
                    MessageBox.Show("Записей с таким названием нет");
                    SearchName.Text = "";
                }
            }
            //Фильтрация по размеру скидки
            switch (Filtering.SelectedIndex)
            {
                case 0:
                    {
                        product = product.ToList();
                    }
                    break;
                case 1:
                    {
                        product = product.Where(x => ((x.ProductDiscountAmount >= 0) && (x.ProductDiscountAmount < 10))).ToList();
                    }
                    break;
                case 2:
                    {
                        product = product.Where(x => ((x.ProductDiscountAmount >= 10) && (x.ProductDiscountAmount < 15))).ToList();
                    }
                    break;
                case 3:
                    {
                        product = product.Where(x => (x.ProductDiscountAmount>= 15)).ToList();

                    }
                    break;
                
            }
            //сортировка
            switch (Sorting.SelectedIndex)
            {
                case 0:
                    {
                        product.Sort((x, y) => x.ProductCost.CompareTo(y.ProductCost));
                    }
                    break;
                case 1:
                    {
                        product.Sort((x, y) => x.ProductCost.CompareTo(y.ProductCost));
                        product.Reverse();
                    }
                    break;
            }

            ListProduct.ItemsSource = product;
            
//количество записей на странице
            if (product.Count == 0)
            {
                MessageBox.Show("нет записей");
                CountProduct.Text = ClassDBase.DB.Product.ToList().Count + "/" + ClassDBase.DB.Product.ToList().Count;
                SearchName.Text = "";
                Sorting.SelectedIndex = 0;
                Filtering.SelectedIndex = 0;

            }
            CountProduct.Text = product.Count + "/" + ClassDBase.DB.Product.ToList().Count;
        }
// добавление в корзину
// в классе с создание объекта бд
public static List<Product> products = new List<Product>();
// событие на правую кнопку мыши
<Grid.ContextMenu>
                                <ContextMenu>
                                    <MenuItem Header="Добавить к заказу" Click="MenuItem_Click" Uid="{Binding ProductArticleNumber}"/>
                                </ContextMenu>
</Grid.ContextMenu>
  private void MenuItem_Click(object sender, RoutedEventArgs e)
        {
            MenuItem mi = (MenuItem)sender;
            string index = mi.Uid;
            Product product = ClassDBase.DB.Product.FirstOrDefault(x => x.ProductArticleNumber == index);
            ClassDBase.products.Add(product);
            ShowOrders.Visibility = Visibility.Visible;
        }
// обновление суммы товаров корзины
  private void ButonDelete_Click(object sender, RoutedEventArgs e)
        {
            Button Buton = (Button)sender;
            int index = Convert.ToInt32(Buton.Uid);
            ProductBasket productBasket = bascet.FirstOrDefault(x => x.product.ID == index);
            _ = bascet.Remove(productBasket);
            if (bascet.Count == 0)
            {
                Close();
            }
            lvProduct.Items.Refresh();
            calculateSummaAndDiscount();
        }

        /// <summary>
        /// Подсчёт суммы заказа и скидок
        /// </summary>
        private void calculateSummaAndDiscount()
        {
            summa = 0;
            summaDiscount = 0;
            foreach (ProductBasket productBasket in bascet)
            {
                summa += productBasket.count * productBasket.product.costWithDiscount;
                summaDiscount += productBasket.count * ((double)productBasket.product.ProductCost - productBasket.product.costWithDiscount);
            }
            TBSumma.Text = "Сумма заказа: " + summa.ToString("0.00") + " руб.";
            TBSummaDiscount.Text = "Сумма скидки: " + summaDiscount.ToString("0.00") + " руб.";
        }

        private void TextBox_TextChanged(object sender, TextChangedEventArgs e)
        {
            TextBox TB = (TextBox)sender;
            int index = Convert.ToInt32(TB.Uid);
            ProductBasket productBasket = bascet.FirstOrDefault(x => x.product.ID == index);
            productBasket.count = TB.Text.Replace(" ", "") == "" ? 0 : Convert.ToInt32(TB.Text);
            if (productBasket.count == 0) // Если колличество 0, то продукт из корзины удаляется
            {
                _ = bascet.Remove(productBasket);
            }
            if (bascet.Count == 0) // Если в корзине нет товаров, то окно закрывается
            {
                Close();
            }
            lvProduct.Items.Refresh();
            calculateSummaAndDiscount();
        }

// вывод на всякий
<ListView Grid.Row="3" Name="ListProduct" Height="300" ScrollViewer.HorizontalScrollBarVisibility="Hidden" HorizontalContentAlignment="Stretch">
            <ListView.ItemTemplate>
                <DataTemplate>
                    <Border Style="{StaticResource BorderStyle}">
                        <Grid Height="150"  VerticalAlignment="Center"  Background="{Binding Brush}">
                            <Grid.ContextMenu>
                                <ContextMenu>
                                    <MenuItem Header="Добавить к заказу" Click="MenuItem_Click" Uid="{Binding ProductArticleNumber}"/>
                                </ContextMenu>
                            </Grid.ContextMenu>
                            <Grid.ColumnDefinitions>
                                <ColumnDefinition Width="300"/>
                                <ColumnDefinition/>
                                <ColumnDefinition/>
                            </Grid.ColumnDefinitions>
                            <Grid Grid.Column="0" >
                                <Image Width="100" Height="100" Source="{Binding ProductPhoto, TargetNullValue={StaticResource defaultImage}}"/>
                            </Grid>
                            <Grid Grid.Column="1">
                                <Grid>
                                    <StackPanel>
                                        <StackPanel Orientation="Horizontal">
                                            <TextBlock Text="Название:"/>
                                            <TextBlock Name="product" Text="{Binding ProductName}" FontWeight="Bold" Style="{StaticResource TextList}"></TextBlock>
                                        </StackPanel>
                                        <StackPanel Orientation="Horizontal">
                                            <TextBlock Text="Описание:"/>
                                            <TextBlock Name="Description" Text="{Binding ProductDescription}" Style="{StaticResource TextList}"></TextBlock>
                                        </StackPanel>
                                        <StackPanel Orientation="Horizontal">
                                            <TextBlock Text="Производитель:"/>
                                            <TextBlock Name="Manufacturer" Text="{Binding Manufacturer.NameProductManufacturer}" Style="{StaticResource TextList}"></TextBlock>
                                        </StackPanel>
                                        <StackPanel Orientation="Horizontal">
                                            <TextBlock Text="Цена:"/>
                                            <TextBlock Name="Price" Text="{Binding Price}" Style="{StaticResource TextList}"></TextBlock>
                                            <TextBlock Name="Cost" Text="{Binding Cost}" TextDecorations="Strikethrough" Style="{StaticResource TextList}"></TextBlock>
                                        </StackPanel>                                     
                                    </StackPanel>
                                </Grid>                                
                            </Grid>
                            <Grid Grid.Column="2">
                                <Grid.RowDefinitions>
                                    <RowDefinition Height="1*"/>
                                    <RowDefinition Height="1*"/>
                                </Grid.RowDefinitions>
                                <StackPanel Orientation="Horizontal" Grid.Row="0">
                                    <TextBlock Name="Discount" Text="{Binding Discount}" Style="{StaticResource TextList}"></TextBlock>
                                </StackPanel>
                                <Button Grid.Row="1" Name="Delete" Visibility="Collapsed" Content="Удалить" Click="Delete_Click" Uid="{Binding ProductArticleNumber}" Loaded="Delete_Loaded" Template="{StaticResource ButtonInElement}"/>
                            </Grid>
                        </Grid>
                    </Border>
                </DataTemplate>
            </ListView.ItemTemplate>
        </ListView>    
// частичный класс 
               public partial class Order
    {
        public string FullName
        {
            get
            {
                return User.UserSurname + " " + User.UserName + " " + User.UserPatronymic;
            }
        }
                
        public string OrderComposition
        {
            get
            {
                string str = "Состав заказа: ";
                List<OrderProduct> orderProducts = ClassDBase.DB.OrderProduct.Where(x => x.OrderID == OrderID).ToList();
                foreach (OrderProduct prod in orderProducts)
                {
                    Product product = ClassDBase.DB.Product.FirstOrDefault(z => z.ProductArticleNumber == prod.ProductArticleNumber);
                    str += product.ProductName + " (" + product.ProductArticleNumber + "), ";
                }
                str = str.Substring(0, str.Length - 2);
                return str;
            }
        }

        public string OrderAmountPrint
        {
            get
            {
                double resultCost = 0;
                List<OrderProduct> orderProducts = ClassDBase.DB.OrderProduct.Where(x => x.OrderID == OrderID).ToList();
                foreach (OrderProduct prod in orderProducts)
                {
                    Product product = ClassDBase.DB.Product.FirstOrDefault(z => z.ProductArticleNumber == prod.ProductArticleNumber);
                    resultCost += product.CostOrder;
                }
                return "Стоимость заказа: " + resultCost;
            }
        }

        public double OrderAmount
        {
            get
            {
                double resultCost = 0;
                List<OrderProduct> orderProducts = ClassDBase.DB.OrderProduct.Where(x => x.OrderID == OrderID).ToList();
                foreach (OrderProduct orderProduct in orderProducts)
                {
                    Product product = ClassDBase.DB.Product.FirstOrDefault(z => z.ProductArticleNumber == orderProduct.ProductArticleNumber);
                    resultCost += product.CostOrder;
                }
                return resultCost;
            }
        }

        public string DiscountOrderPrint
        {
            get
            {
                double discount = 0;
                double withoutDiscount = 0;
                double newAmount = 0;
                List<OrderProduct> orderProducts = ClassDBase.DB.OrderProduct.Where(x => x.OrderID == OrderID).ToList();
                foreach (OrderProduct prod in orderProducts)
                {
                    Product product = ClassDBase.DB.Product.FirstOrDefault(z => z.ProductArticleNumber == prod.ProductArticleNumber);
                    withoutDiscount += (double)product.ProductCost;
                    newAmount += product.CostOrder;
                }
                discount = 100 - 100 * newAmount / withoutDiscount;
                return "Общая скидка: " + discount + "%";
            }
        }

        public double DiscountOrder
        {
            get
            {
                double discount = 0;
                double withoutDiscount = 0;
                double newAmount = 0;
                List<OrderProduct> orderProducts = ClassDBase.DB.OrderProduct.Where(x => x.OrderID == OrderID).ToList();
                foreach (OrderProduct prod in orderProducts)
                {
                    Product product = ClassDBase.DB.Product.FirstOrDefault(z => z.ProductArticleNumber == prod.ProductArticleNumber);
                    withoutDiscount += (double)product.ProductCost;
                    newAmount += product.CostOrder;
                }
                discount = 100 - 100 * newAmount / withoutDiscount;
                return discount;
            }
        }

        public SolidColorBrush ColorOrder
        {
            get
            {
                bool moreThree = false;
                bool zero = false;
                List<OrderProduct> orderProducts = ClassDBase.DB.OrderProduct.Where(x => x.OrderID == OrderID).ToList();
                foreach (OrderProduct prod in orderProducts)
                {
                    Product product = ClassDBase.DB.Product.FirstOrDefault(z => z.ProductArticleNumber == prod.ProductArticleNumber);
                    if (product.ProductQuantityInStock > 3)
                    {
                        moreThree = true;
                    }
                    else
                    {
                        moreThree = false;
                        if (product.ProductQuantityInStock == 0)
                        {
                            moreThree = false;
                            zero = true;
                            goto met;
                        }
                    }
                }
            met: if (moreThree == true)
                {
                    return (SolidColorBrush)new BrushConverter().ConvertFrom("#20b2aa");
                }
                else if (zero == true)
                {
                    return (SolidColorBrush)new BrushConverter().ConvertFrom("#ff8c00");
                }
                else
                {
                    return Brushes.White;
                }
            }
        }
    }
              
// и еще один
              public partial class Product
    {
        public SolidColorBrush Brush
        {
            get
            {
                var brushConverter = new BrushConverter();

                if (ProductDiscountAmount < 15 || ProductDiscountAmount == null)
                {
                    return Brushes.White;
                }
                else
                {
                    return (SolidColorBrush)(Brush)brushConverter.ConvertFrom("#7fff00");

                }

            }
        }
        public string Price
        {
            get
            {
                if (ProductDiscountAmount != null)
                {
                    double b = (Convert.ToDouble(ProductCost) / 100) * (100 - ProductDiscountAmount.Value);                   
                    return b + "";
                }
                else
                {
                    double a = Convert.ToDouble(ProductCost);                   
                    return a + "";
                }
            }
        }
        public string Cost

        {
            get
            {
                if (ProductDiscountAmount != null)
                {
                   
                    return Math.Round(Convert.ToDouble(ProductCost)) + " ";
                }
                return "";

            }
        }
        public double PriceOrder
        {
            get
            {
                if (ProductDiscountAmount != null)
                {
                    double b = (Convert.ToDouble(ProductCost) / 100) * (100 - ProductDiscountAmount.Value);
                    return b;
                }
                else
                {
                    double a = Convert.ToDouble(ProductCost);
                    return a;
                }
            }
        }
        public double CostOrder

        {
            get
            {
                if (ProductDiscountAmount != null)
                {

                    return Math.Round(Convert.ToDouble(ProductCost));
                }

                return 0;
            }
        }

        public string Discount
        {
            get
            {
                return ProductDiscountAmount + "%";
            }
        }
    }