WPF implement ICommand with async execute

public class DelCommand : ICommand
{
    private Action<object?>? syncExecute;
    private readonly Func<object?, Task> asyncExecute;
    private Predicate<object?>? canExecute;
    public DelCommand(Action<object?>? executeValue, Predicate<object?>? canExecuteValue = null)
    {
        syncExecute = executeValue ?? throw new ArgumentNullException(nameof(executeValue));
        canExecute = canExecuteValue;
    }

    public DelCommand(Func<object?, Task> asyncExecuteValue, Predicate<object?>? canExecuteValue = null)
    {
        asyncExecute = asyncExecuteValue ?? throw new ArgumentNullException(nameof(asyncExecuteValue));
        canExecute = canExecuteValue;
    }

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

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

    public async void Execute(object? parameter)
    {
        if (!CanExecute(parameter))
        {
            return;
        }

        if (asyncExecute != null)
        {
            await asyncExecute(parameter);
        }
        else if (syncExecute != null)
        {
            syncExecute(parameter);
        }
    }
}

private ICommand mouseDownCommand;
public ICommand MouseDownCommand
{
    get
    {
        if (mouseDownCommand == null)
        {
            mouseDownCommand = new DelCommand(MouseDownCommandExecuted);
        }
        return mouseDownCommand;
    }
}

private async Task MouseDownCommandExecuted(object? obj)
{
    var btnEventArgs = obj as MouseButtonEventArgs;
    if (btnEventArgs != null)
    {
        await InitBooksCollectionAsync();
        string msg = $"MinId:{BooksCollection.OrderBy(x => x.Id).FirstOrDefault()?.Id}\n" +
            $"MaxId:{BooksCollection.OrderByDescending(x => x.Id).FirstOrDefault()?.Id}";
        MessageBox.Show($"{msg}", 
            $"{DateTime.Now}");
    }
}

private async Task InitBooksCollectionAsync()
{
    string dataUrl = "https://localhost:7146/api/book";
    using (HttpClient client = new HttpClient())
    {
        string jsonStr = await client.GetStringAsync(dataUrl);
        if (!string.IsNullOrWhiteSpace(jsonStr))
        {
            List<Book>? bksList = JsonConvert.DeserializeObject<List<Book>>(jsonStr);
            if (bksList != null && bksList.Any())
            {
                BooksCollection = new ObservableCollection<Book>(bksList);
                MainTitle = $"{DateTime.Now},loaded last idx:{bksList.OrderByDescending(x => x.Id).FirstOrDefault()?.Id}";
            }
        }
    }
}

 

 

 

 

 

 

 

 

 

 

 

 

//WebAPI
namespace WebApplication2.Models
{
    public class Book
    {
        public int Id {  get; set; }
        public string Name {  get; set; }
        public string ISBN {  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; }
    }
}
using WebApplication2.Models;

namespace WebApplication2.Services
{
    public class BookService:IDisposable
    {
        int idx = 0;
        private int GetIdx()
        {
            return Interlocked.Increment(ref idx);
        }

        public List<Book> GetBooksList(int cnt=10000)
        {
            List<Book> booksList=new List<Book>();
            for(int i=0;i<cnt;i++)
            {
                int a=GetIdx();
                booksList.Add(new Book()
                {
                    Id = a,
                    Name = $"Name_{a}",
                    ISBN = $"ISBN_{a}_{Guid.NewGuid():N}",
                    Comment =$"Comment_{a}",
                    Content=$"Content_{a}",
                    Title=$"Title_{a}",
                    Topic=$"Topic_{a}"
                });
            }
            return booksList;
        }

        public void Dispose()
        {
            idx = 0;
        }
    }
}
using Microsoft.AspNetCore.Mvc;
using WebApplication2.Models;
using WebApplication2.Services;

namespace WebApplication2.Controllers
{
    [ApiController]
    [Route("api/[controller]")]
    public class BookController : Controller
    {
        private BookService bkService;
        public BookController(BookService bkServiceValue)
        {
            bkService= bkServiceValue;
        }

        [HttpGet]
        [ProducesResponseType(StatusCodes.Status200OK)]
        public ActionResult<List<Book>> GetBooksList()
        {
            var bksList = bkService.GetBooksList();
            return Ok(bksList);
        }



    }
}

using WebApplication2.Services;

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

            // Add services to the container.

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

            builder.Services.AddSingleton<BookService>();
            var app = builder.Build();

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

            app.UseHttpsRedirection();

            app.UseAuthorization();


            app.MapControllers();

            app.Run();
        }
    }
}



//WPF
<Window x:Class="WpfApp7.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:WpfApp7"
        xmlns:behavior="http://schemas.microsoft.com/xaml/behaviors"
        mc:Ignorable="d"
        WindowState="Maximized"
        Title="{Binding MainTitle}" Height="450" Width="800">
    <behavior:Interaction.Triggers>
        <behavior:EventTrigger EventName="MouseDown">
            <behavior:InvokeCommandAction
                    Command="{Binding MouseDownCommand}"
                 PassEventArgsToCommand="True"/>
        </behavior:EventTrigger>
    </behavior:Interaction.Triggers>
    <Window.DataContext>
        <local:MainVM/>
    </Window.DataContext>
    <Grid>
        <DataGrid ItemsSource="{Binding BooksCollection}"
                  IsReadOnly="True"
                  VirtualizingPanel.IsVirtualizing="True"
                  VirtualizingPanel.VirtualizationMode="Recycling"
                  EnableRowVirtualization="True"
                  EnableColumnVirtualization="True"
                  ScrollViewer.CanContentScroll="True"
                  ScrollViewer.IsDeferredScrollingEnabled="True"
                  VirtualizingPanel.CacheLength="2,2"
                  VirtualizingPanel.CacheLengthUnit="Item"
                  AutoGenerateColumns="True"
                  CanUserAddRows="False">
            <DataGrid.Resources>
                <Style TargetType="DataGridRow">
                    <Setter Property="FontSize" Value="30"/>
                    <Style.Triggers>
                        <Trigger Property="IsMouseOver" Value="True">
                            <Setter Property="FontSize" Value="50"/>
                            <Setter Property="Foreground" Value="Red"/>
                        </Trigger>
                    </Style.Triggers>
                </Style>
            </DataGrid.Resources>
            <behavior:Interaction.Triggers>
                <behavior:EventTrigger EventName="PreviewMouseDown">
                    <behavior:InvokeCommandAction
                    Command="{Binding MouseDownCommand}"
                 PassEventArgsToCommand="True"/>
                </behavior:EventTrigger>
            </behavior:Interaction.Triggers>
        </DataGrid>
    </Grid>
</Window>

using System.Collections.ObjectModel;
using System.ComponentModel;
using System.Net.Http;
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;
using Newtonsoft.Json;

namespace WpfApp7
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
        }
    }

    public class MainVM : INotifyPropertyChanged
    {
        public MainVM()
        {
            _=InitBooksCollectionAsync();
        }

        private ICommand mouseDownCommand;
        public ICommand MouseDownCommand
        {
            get
            {
                if (mouseDownCommand == null)
                {
                    mouseDownCommand = new DelCommand(MouseDownCommandExecuted);
                }
                return mouseDownCommand;
            }
        }

        private async Task MouseDownCommandExecuted(object? obj)
        {
            var btnEventArgs = obj as MouseButtonEventArgs;
            if (btnEventArgs != null)
            {
                await InitBooksCollectionAsync();
                string msg = $"MinId:{BooksCollection.OrderBy(x => x.Id).FirstOrDefault()?.Id}\n" +
                    $"MaxId:{BooksCollection.OrderByDescending(x => x.Id).FirstOrDefault()?.Id}";
                MessageBox.Show($"{msg}", 
                    $"{DateTime.Now}");
            }
        }

        private async Task InitBooksCollectionAsync()
        {
            string dataUrl = "https://localhost:7146/api/book";
            using (HttpClient client = new HttpClient())
            {
                string jsonStr = await client.GetStringAsync(dataUrl);
                if (!string.IsNullOrWhiteSpace(jsonStr))
                {
                    List<Book>? bksList = JsonConvert.DeserializeObject<List<Book>>(jsonStr);
                    if (bksList != null && bksList.Any())
                    {
                        BooksCollection = new ObservableCollection<Book>(bksList);
                        MainTitle = $"{DateTime.Now},loaded last idx:{bksList.OrderByDescending(x => x.Id).FirstOrDefault()?.Id}";
                    }
                }
            }
        }

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

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

        public event PropertyChangedEventHandler? PropertyChanged;

        private void OnPropertyChanged([CallerMemberName] string propertyName = "")
        {
            var handler = PropertyChanged;
            if (handler != null)
            {
                handler?.Invoke(this, new PropertyChangedEventArgs(propertyName));
            }
        }
    }


    public class DelCommand : ICommand
    {
        private Action<object?>? syncExecute;
        private readonly Func<object?, Task> asyncExecute;
        private Predicate<object?>? canExecute;
        public DelCommand(Action<object?>? executeValue, Predicate<object?>? canExecuteValue = null)
        {
            syncExecute = executeValue ?? throw new ArgumentNullException(nameof(executeValue));
            canExecute = canExecuteValue;
        }

        public DelCommand(Func<object?, Task> asyncExecuteValue, Predicate<object?>? canExecuteValue = null)
        {
            asyncExecute = asyncExecuteValue ?? throw new ArgumentNullException(nameof(asyncExecuteValue));
            canExecute = canExecuteValue;
        }

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

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

        public async void Execute(object? parameter)
        {
            if (!CanExecute(parameter))
            {
                return;
            }

            if (asyncExecute != null)
            {
                await asyncExecute(parameter);
            }
            else if (syncExecute != null)
            {
                syncExecute(parameter);
            }
        }
    }

    public class Book
    {
        public int Id { get; set; }
        public string Name { get; set; }
        public string ISBN { 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; }
    }
}