WPF usercontrol listbox mvvm contextmenu memuitem command commandparameter

//xaml
<UserControl x:Class="WpfApp155.UCLbx"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
             xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
             xmlns:local="clr-namespace:WpfApp155"
             mc:Ignorable="d" 
             d:DesignHeight="450" d:DesignWidth="800">
    <Grid>
        <ListBox
                ItemsSource="{Binding BooksCollection,Mode=TwoWay,UpdateSourceTrigger=PropertyChanged}"
                Width="{Binding ActualWidth,RelativeSource={RelativeSource Mode=FindAncestor,AncestorType={x:Type Window}}}"
                Height="{Binding ActualHeight,RelativeSource={RelativeSource Mode=FindAncestor,AncestorType={x:Type Window}}}"
                VirtualizingPanel.IsVirtualizing="True"
                VirtualizingPanel.VirtualizationMode="Recycling"
                >
            <ListBox.ItemTemplate>
                <DataTemplate>
                    <Grid
                        TextBlock.FontSize="100"
                        TextBlock.Foreground="Red"
                         Width="{Binding ActualWidth,RelativeSource={RelativeSource Mode=FindAncestor,AncestorType={x:Type Window}}}"
                         Height="{Binding ActualHeight,RelativeSource={RelativeSource Mode=FindAncestor,AncestorType={x:Type Window}}}">
                        <Grid.Background>
                            <ImageBrush ImageSource="{Binding DataContext.ImgSource,RelativeSource={RelativeSource 
                                Mode=FindAncestor,AncestorType={x:Type ListBoxItem}}}"
                                        Stretch="Uniform"/>
                        </Grid.Background>
                        <Grid.RowDefinitions>
                            <RowDefinition/>
                            <RowDefinition/>
                        </Grid.RowDefinitions>
                        <Grid.ColumnDefinitions>
                            <ColumnDefinition/>
                            <ColumnDefinition/>
                            <ColumnDefinition/>
                        </Grid.ColumnDefinitions>
                        <TextBlock Grid.Row="0"
                                   Grid.Column="0"
                                   Text="{Binding DataContext.Id,RelativeSource={RelativeSource Mode=FindAncestor,AncestorType={x:Type ListBoxItem}}}"/>
                        <TextBlock Grid.Row="0"
                                   Grid.Column="1"
                                   Text="{Binding DataContext.Name,RelativeSource={RelativeSource Mode=FindAncestor,AncestorType={x:Type ListBoxItem}}}"/>
                        <TextBlock Grid.Row="0"
                                   Grid.Column="2"
                                   Text="{Binding DataContext.Topic,RelativeSource={RelativeSource Mode=FindAncestor,AncestorType={x:Type ListBoxItem}}}"/>
                        <TextBlock Grid.Row="1"
                                   Grid.Column="0"
                                   Grid.ColumnSpan="3"
                                   Text="{Binding DataContext.ISBN,RelativeSource={RelativeSource Mode=FindAncestor,AncestorType={x:Type ListBoxItem}}}"/>
                        
                    </Grid>
                </DataTemplate>
            </ListBox.ItemTemplate>
            <ListBox.ContextMenu>
                <ContextMenu>
                    <MenuItem Header="Export">
                        <MenuItem Header="Export CSV"
                                  Command="{Binding ExportCSVCommand}"
                                  CommandParameter="{Binding Path=PlacementTarget,RelativeSource={RelativeSource 
                            Mode=FindAncestor,AncestorType={x:Type ContextMenu}}}"/>
                    </MenuItem>
                </ContextMenu>
            </ListBox.ContextMenu>
        </ListBox>
    </Grid>
</UserControl>


//cs
using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.ComponentModel;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;
using Newtonsoft.Json;

namespace WpfApp155
{
    /// <summary>
    /// Interaction logic for UCLbx.xaml
    /// </summary>
    public partial class UCLbx : UserControl
    {
        public UCLbx()
        {
            InitializeComponent();
            var vm = new UCLbxVM();
            this.DataContext = vm;
        }
    }

    public class UCLbxVM : INotifyPropertyChanged
    {

        public UCLbxVM()
        {
            InitBooksCollection();
            InitCommands();
        }

        private void InitCommands()
        {
            ExportCSVCommand = new DelCommand(ExportCSVCommandExecuted);
        }

        private void ExportCSVCommandExecuted(object? obj)
        {
            var lbx = obj as ListBox;
            if (lbx != null)
            {
                var jsonStr = JsonConvert.SerializeObject(lbx.ItemsSource, Formatting.Indented);
                string jsonFile = $"Json_{DateTime.UtcNow.ToString("yyyyMMddHHmmssffff")}.json";
                File.WriteAllText(jsonFile, jsonStr);
                MessageBox.Show(jsonFile, "Saved in Json");
            }
        }

        public DelCommand ExportCSVCommand { get; set; }

        private void InitBooksCollection()
        {
            BooksCollection = new ObservableCollection<Book>();
            var imgs = Directory.GetFiles(@"../../../Images");
            int imgsCount = imgs.Count();
            for (int i = 0; i < 100; i++)
            {
                BooksCollection.Add(new Book()
                {
                    Id = i + 1,
                    Name = $"Name_{i + 1}",
                    ISBN = $"ISBN_{Guid.NewGuid().ToString("N")}",
                    Topic = $"Topic_{i + 1}",
                    ImgSource = GetImgSourceViaUrl(imgs[i % imgsCount])
                });
            }
        }

        private ImageSource GetImgSourceViaUrl(string imgUrl)
        {
            BitmapImage bmi = new BitmapImage();
            bmi.BeginInit();
            bmi.UriSource = new Uri(imgUrl, UriKind.RelativeOrAbsolute);
            bmi.EndInit();
            if (bmi.CanFreeze)
            {
                bmi.Freeze();
            }
            return bmi;
        }

        private ObservableCollection<Book> booksCollection;
        public ObservableCollection<Book> BooksCollection
        {
            get
            {
                return booksCollection;
            }
            set
            {
                if (value != booksCollection)
                {
                    booksCollection = value;
                    OnPropertyChanged(nameof(BooksCollection));
                }
            }
        }

        public event PropertyChangedEventHandler? PropertyChanged;
        private void OnPropertyChanged(string propertyName)
        {
            var handler = PropertyChanged;
            if (handler != null)
            {
                handler(this, new PropertyChangedEventArgs(propertyName));
            }
        }
    }
}










//
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Input;

namespace WpfApp155
{
    public class DelCommand : ICommand
    {
        private Action<object?> execute;
        private Predicate<object?> canExecute;
        public DelCommand(Action<object?> executeValue, Predicate<object?> canExecuteValue = null)
        {
            execute = executeValue;
            canExecute = canExecuteValue;
        }

        public event EventHandler? CanExecuteChanged
        {
            add
            {
                CommandManager.RequerySuggested += value;
            }
            remove
            {
                CommandManager.RequerySuggested -= value;
            }
        }

        public bool CanExecute(object? parameter)
        {
            if (canExecute == null)
            {
                return true;
            }
            return canExecute(parameter);
        }

        public void Execute(object? parameter)
        {
            execute(parameter);
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Media;

namespace WpfApp155
{
    public class Book
    {
        public int Id { get; set; }

        public string Name { get; set; }

        public string ISBN { get; set; }

        public string Topic { get; set; }

        public ImageSource ImgSource { get; set; }
    }
}

 

 

 

<Window x:Class="WpfApp155.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:WpfApp155"
        WindowState="Maximized"
        mc:Ignorable="d"
        Title="MainWindow" Height="450" Width="800">
    <Grid>
        <local:UCLbx/>
    </Grid>
</Window>