//D:\C\WebApplication2\BooksController.cs

using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Mvc;
using WebApplication2.Models;

namespace WebApplication2
{
    [Route("api/[controller]")]
    [ApiController]
    public class BooksController : ControllerBase
    {
        private static long id = 1;
        private static (long, long) GetStartEnd(int cnt)
        {
            var end = Interlocked.Add(ref id, cnt);
            var start = end - cnt;
            return (start, end);
        }

        [HttpGet("/getbooks/{cnt}")]
        public List<Book> GetBooksList(int cnt = 1000000)
        {
            List<Book> bksList = new List<Book>(cnt);
            var (start, end) = GetStartEnd(cnt);
            for (long i = start; i < end; i++)
            {
                bksList.Add(new Book()
                {
                    Id = i,
                    Name = $"Name_{i}",
                    Comment = $"Comment_{i}",
                    Content = $"Content_{i}",
                    Author = $"Author_{i}",
                    ISBN = $"ISBN_{i}_{Guid.NewGuid():N}",
                    Summary = $"Summary_{i}",
                    Title = $"Title_{i}",
                    Topic = $"Topic_{i}"
                });
            }
            return bksList;
        }
    }
}


//D:\C\WebApplication2\Models\Book.cs
namespace WebApplication2.Models
{
    public class Book
    {
        public long Id { get; set; }
        public string Name { get; set;  }
        public string ISBN { get; set;  }
        public string Author { get; set;  }
        public string Comment { get; set; }
        public string Content { get; set; }
        public string Summary { get; set;  }
        public string Title { get; set; }
        public string Topic { get; set;  }
    }
}

//D:\C\WebApplication2\Program.cs

namespace WebApplication2
{
    public class Program
    {
        public static void Main(string[] args)
        {
            var builder = WebApplication.CreateBuilder(args);

            builder.WebHost.UseKestrel(x =>
            {
                x.ListenLocalhost(5000);
                x.ListenLocalhost(5001, o =>
                {
                    o.UseHttps();
                });
            });
            // Add services to the container.

            builder.Services.AddControllers();
            // Learn more about configuring OpenAPI at https://aka.ms/aspnet/openapi
            builder.Services.AddOpenApi();

            var app = builder.Build();

            // Configure the HTTP request pipeline.
            if (app.Environment.IsDevelopment())
            {
                app.MapOpenApi();
            }

            //app.UseHttpsRedirection();

            app.UseAuthorization();


            app.MapControllers();

            app.Run();
        }
    }
}

//

            var builder = WebApplication.CreateBuilder(args);

            builder.WebHost.UseKestrel(x =>
            {
                x.ListenLocalhost(5000);
                x.ListenLocalhost(5001, o =>
                {
                    o.UseHttps();
                });
            });

warn: Microsoft.AspNetCore.Server.Kestrel[0]
      Overriding address(es) 'https://localhost:7123, http://localhost:5062'. Binding to endpoints defined via IConfiguration and/or UseKestrel() instead.
info: Microsoft.Hosting.Lifetime[14]
      Now listening on: http://localhost:5000
info: Microsoft.Hosting.Lifetime[14]
      Now listening on: https://localhost:5001
info: Microsoft.Hosting.Lifetime[0]
      Application started. Press Ctrl+C to shut down.
info: Microsoft.Hosting.Lifetime[0]
      Hosting environment: Development
info: Microsoft.Hosting.Lifetime[0]
      Content root path: D:\C\WebApplication2

   <DataGrid.Columns>
       <DataGridTemplateColumn>
           <DataGridTemplateColumn.CellTemplate>
               <DataTemplate>
                   <ContentPresenter ContentTemplate="{StaticResource BookDataTemplate}"/>
               </DataTemplate>
           </DataGridTemplateColumn.CellTemplate>
       </DataGridTemplateColumn>
   </DataGrid.Columns>

Install-Package Newtonsoft.Json

<Window x:Class="WpfApp5.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:WpfApp5"
        mc:Ignorable="d"
        Title="{Binding MainTitle}" WindowState="Maximized">
    <Window.DataContext>
        <local:MainVM/>
    </Window.DataContext>
    <Window.Resources>

        <Style TargetType="TextBlock" x:Key="TbkStyle">
            <Setter Property="FontSize" Value="30"/>
            <Style.Triggers>
                <Trigger Property="IsMouseOver" Value="True">
                    <Setter Property="Foreground" Value="Red"/>
                    <Setter Property="FontWeight" Value="ExtraBold"/>
                </Trigger>
            </Style.Triggers>
        </Style>
        
        <DataTemplate DataType="{x:Type local:Book}"
                      x:Key="BookDataTemplate">
            <Grid Margin="5"
                  Width="{x:Static SystemParameters.PrimaryScreenWidth}">
                <Grid.Resources>
                    <Style TargetType="TextBlock" BasedOn="{StaticResource TbkStyle}"/>
                </Grid.Resources>
                <Grid.RowDefinitions>
                    <RowDefinition/>
                    <RowDefinition/>
                    <RowDefinition/>
                </Grid.RowDefinitions>
                <Grid.ColumnDefinitions>
                    <ColumnDefinition Width="*"/>
                    <ColumnDefinition MaxWidth="300"/>
                    <ColumnDefinition MaxWidth="300"/>
                </Grid.ColumnDefinitions>
                <TextBlock Text="{Binding Id}" Grid.Row="0" Grid.Column="0"/>
                <TextBlock Text="{Binding Name}" Grid.Row="0" Grid.Column="1"/>
                <TextBlock Text="{Binding Author}" Grid.Row="0" Grid.Column="2"/>
                <TextBlock Text="{Binding ISBN}" Grid.Row="1" Grid.Column="0"/>
                <TextBlock Text="{Binding Comment}" Grid.Row="1" Grid.Column="1"/>
                <TextBlock Text="{Binding Content}" Grid.Row="1" Grid.Column="2"/>
                <TextBlock Text="{Binding Summary}" Grid.Row="2" Grid.Column="0"/>
                <TextBlock Text="{Binding Title}" Grid.Row="2" Grid.Column="1"/>
                <TextBlock Text="{Binding Topic}" Grid.Row="2" Grid.Column="2"/>
            </Grid>
        </DataTemplate>

        <ControlTemplate TargetType="ContentControl"
                         x:Key="DGTemplate">
            <DataGrid ItemsSource="{Binding BksCollection}"
                      VirtualizingPanel.IsVirtualizing="True"
                      VirtualizingPanel.VirtualizationMode="Recycling"
                      VirtualizingPanel.CacheLength="5,5"
                      VirtualizingPanel.CacheLengthUnit="Item"
                      ScrollViewer.CanContentScroll="True"
                      ScrollViewer.IsDeferredScrollingEnabled="True"
                      UseLayoutRounding="True"
                      SnapsToDevicePixels="True"
                      AutoGenerateColumns="False"
                      CanUserAddRows="False"
                      SelectionMode="Extended">
                <DataGrid.Columns>
                    <DataGridTemplateColumn>
                        <DataGridTemplateColumn.CellTemplate>
                            <DataTemplate>
                                <ContentPresenter ContentTemplate="{StaticResource BookDataTemplate}"/>
                            </DataTemplate>
                        </DataGridTemplateColumn.CellTemplate>
                    </DataGridTemplateColumn>
                </DataGrid.Columns>
                <DataGrid.ContextMenu>
                    <ContextMenu>
                        <MenuItem Header="Export Selected as Json"
                                  Width="400"
                                  FontSize="30"
                                  Command="{Binding ExportSelectedAsJsonCommand}"
                                  CommandParameter="{Binding RelativeSource={RelativeSource AncestorType=ContextMenu},
                            Path=PlacementTarget.SelectedItems}" />
                    </ContextMenu>
                </DataGrid.ContextMenu>
            </DataGrid>                      
        </ControlTemplate>
    </Window.Resources>
    <Grid>
        <ContentControl Template="{StaticResource DGTemplate}"/>
    </Grid>
</Window>


using Microsoft.Win32;
using Newtonsoft.Json;
using System.Collections.ObjectModel;
using System.ComponentModel;
using System.IO;
using System.Net.Http;
using System.Reflection.Metadata;
using System.Runtime.CompilerServices;
using System.Text;
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;

namespace WpfApp5
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
        }
    }

    public class MainVM : INotifyPropertyChanged
    {
        string url = "http://localhost:5000/getbooks/";
        private static HttpClient client = new HttpClient()
        {
            Timeout = TimeSpan.FromHours(1)
        };

        private bool isLoading = false;

        public MainVM()
        {
            if (!DesignerProperties.GetIsInDesignMode(new DependencyObject()))
            {
                _ = AutoLoadBooksAsync();
            }
        }

        private async Task AutoLoadBooksAsync(int cnt = 1000000)
        {
            while (true)
            {
                await LoadBooksAsync();
                await Task.Delay(2000);
            }
        }

        private async Task LoadBooksAsync(int cnt = 1000000)
        {
            if (isLoading)
            {
                return;
            }
            isLoading = true;

            MainTitle = $"{DateTime.Now},loading...";
            try
            {
                string jsonStr = await client.GetStringAsync($"{url}{cnt}");
                var bks = JsonConvert.DeserializeObject<List<Book>>(jsonStr);
                if (bks != null && bks.Any())
                {
                    BksCollection = new ObservableCollection<Book>(bks);
                    MainTitle = $"{DateTime.Now},First Id:{BksCollection.FirstOrDefault()?.Id}," +
                        $"LastId:{BksCollection.LastOrDefault()?.Id}";
                    PrintMsg(MainTitle);
                }
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex?.Message);
            }
            finally
            {
                isLoading = false;
            }
        }

        private ICommand exportSelectedAsJsonCommand;
        public ICommand ExportSelectedAsJsonCommand
        {
            get
            {
                if(exportSelectedAsJsonCommand==null)
                {
                    exportSelectedAsJsonCommand = new DelegateCommand(ExportSelectedAsJsonCommandExecuted);
                }
                return exportSelectedAsJsonCommand;
            }
        }

        private void ExportSelectedAsJsonCommandExecuted(object? obj)
        {
            var items = ((System.Collections.IList)obj).Cast<Book>()?.ToList();
            if(items!=null && items.Any())
            {
                SaveFileDialog dlg = new SaveFileDialog();
                dlg.Filter = $"Json Files|*.json|All Files|*.*";
                dlg.FileName = $"Selected{DateTime.Now.ToString("yyyyMMddHHmmssffff")}.json";
                if(dlg.ShowDialog()==true)
                {
                    var jsonStr = JsonConvert.SerializeObject(items, Formatting.Indented);
                    using(StreamWriter writer=new StreamWriter(dlg.FileName,false,Encoding.UTF8))
                    {
                        writer.WriteLine(jsonStr);
                        MessageBox.Show($"Saved selected items to {dlg.FileName}");
                    }
                }
            }
        }

        private string mainTitle = $"{DateTime.Now}";
        public string MainTitle
        {
            get
            {
                return mainTitle;
            }
            set
            {
                if (value != mainTitle)
                {
                    mainTitle = value;
                    OnPropertyChanged();
                }
            }
        }

        private void PrintMsg(string msg)
        {
#if DEBUG
            System.Diagnostics.Debug.WriteLine(msg);
#else
            System.Diagnostics.Trace.WriteLine(msg);
#endif
        }

        private ObservableCollection<Book> bksCollection;
        public ObservableCollection<Book> BksCollection
        {
            get
            {
                return bksCollection;
            }
            set
            {
                if (value != bksCollection)
                {
                    bksCollection = value;
                    OnPropertyChanged();
                }
            }
        }

        public event PropertyChangedEventHandler? PropertyChanged;
        private void OnPropertyChanged([CallerMemberName] string propName = "")
        {
            var handler = Volatile.Read(ref this.PropertyChanged);
            if (handler == null)
            {
                return;
            }
            handler(this, new PropertyChangedEventArgs(propName));
        }
    }

    public class DelegateCommand : ICommand
    {
        private readonly Action<object?> execute;
        private readonly Func<object?, bool>? canExecute;
        public DelegateCommand(Action<object?> executeValue, Func<object?, bool>? canExecuteValue = null)
        {
            execute = executeValue ?? throw new ArgumentNullException(nameof(executeValue));
            canExecute = canExecuteValue;
        }

        public event EventHandler? CanExecuteChanged;

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

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

        public void RaiseCanExecuteChanged()
        {
            var handler = Volatile.Read(ref CanExecuteChanged);
            if (handler == null)
            {
                return;
            }

            var dispatcher = Application.Current.Dispatcher;
            if (dispatcher != null)
            {
                if (dispatcher.CheckAccess())
                {
                    handler(this, EventArgs.Empty);
                }
                else
                {
                    dispatcher.Invoke(() =>
                    {
                        handler(this, EventArgs.Empty);
                    }, System.Windows.Threading.DispatcherPriority.Background);
                }
            }
        }
    }

    public class Book
    {
        public long Id { get; set; }
        public string Name { get; set; }
        public string ISBN { get; set; }
        public string Author { get; set; }
        public string Comment { get; set; }
        public string Content { get; set; }
        public string Summary { get; set; }
        public string Title { get; set; }
        public string Topic { get; set; }
    }
}