Validation.error event in event command

Question

I have a text box:

    <TextBox Height="20" Width="150" Text="{Binding MyProperty,NotifyOnValidationError=True,ValidatesOnDataErrors=True}" >
          <i:Interaction.Triggers>
          <i:EventTrigger EventName="Validation.Error">
                <mvvm:EventToCommand Command="{Binding MyCmd}" PassEventArgsToCommand="True" ></mvvm:EventToCommand>
            </i:EventTrigger>
        </i:Interaction.Triggers>
    </TextBox>

My ViewModel looks like this:

  public class MyViewModel : ValidationViewModelBase, INotifyPropertyChanged
{
    private int myVar;

    [Range(0, 10)]
    public int MyProperty
    {
        get { return myVar; }
        set
        {
            myVar = value;
            OnPropertyChanged("MyProperty");
        }
    }



    public MyViewModel()
    {
        MyCmd = new RelayCommand<RoutedEventArgs>(Valid);
    }

    public RelayCommand<RoutedEventArgs> MyCmd { get; set; }

    private void Valid(RoutedEventArgs args)
    {
        //Do something
    }

    #region INotifyPropertyChanged

    public event PropertyChangedEventHandler PropertyChanged;

    public void OnPropertyChanged(string name)
    {
        if (PropertyChanged != null)
        {
            PropertyChanged(this, new PropertyChangedEventArgs(name));
        }
    }

    #endregion INotifyPropertyChanged
}

When I catch the event Validation.Error in Code Behind it works:

But when I try to run it this way with the Event Command is not coming Valid function.

Did I miss something?

Answer 1

Since Validation.Error is Attached Event, then it does not work with EventToCommand normally.

The answer you will find at the link below:

EventToCommand with attached event

Answer 2

There is no Validation.Error event for TextBox. Furthermore, there is no Validating event for System.Controls.TextBox (which you are using).

Use LostFocus to validate the textbox or see this question if you want to use Validation with MVVM pattern