Simple MVVM example in Windows Forms

This is my simplified example of Klaus Loeffelmann article. With my example will just execute MessageBox.Show("Hello world");

First I have started new WinForms with .NET 8.0 support, and installed nuGet package CommunityToolkit.Mvvm, then I have added new button, and the class SimpleCommandViewModel which inherits INotifyPropertyChanged:

public class SimpleCommandViewModel: INotifyPropertyChanged
{
    public event PropertyChangedEventHandler? PropertyChanged;

    protected void OnPropertyChanged([CallerMemberName] string propertyName = "")
        => PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));

    private RelayCommand _sampleCommand;

    public SimpleCommandViewModel()
    {
        _sampleCommand = new RelayCommand(ExecuteSampleCommand);
    }

    public void ExecuteSampleCommand()
        => MessageBox.Show("Hello world");

    public RelayCommand SampleCommand
    {
        get => _sampleCommand;
        set
        {
            if (_sampleCommand == value)
            {
                return;
            }

            _sampleCommand = value;
            OnPropertyChanged();
        }
    }
}

Here notice:

new RelayCommand(ExecuteSampleCommand);

That means that by default my button is enabled, in comparsion of Klaus Loeffelmann article:

new RelayCommand(ExecuteSampleCommand, CanExecuteSampleCommand);

Where his button will enabled only if CanExecuteSampleCommand is set to true.

Now, build it at least once.

Then in Properties -> DataBindings -> Command -> add new Object DataSource -> choose SimpleCommandViewModel, after choose SampleCommand from dropdown list. In Form Load event add code:

private void Form1_Load(object sender, EventArgs e)
{
	simpleCommandViewModelBindingSource.DataSource = new SimpleCommandViewModel();
}

Example download from here.