[Solved] Set validationState in Behavior

[Matej]

Hi

I am trying set validation state with custom Behavior:
My behaviour is:

public class ValidationBehavior : Behavior<RadTextBox>
   {
       public String ValidationError
       {
           get { return (String)GetValue(ValidationErrorProperty); }
           set { SetValue(ValidationErrorProperty, value); }
       }

       // Using a DependencyProperty as the backing store for ValidationError.  This enables animation, styling, binding, etc...
       public static readonly DependencyProperty ValidationErrorProperty =
           DependencyProperty.Register("ValidationError", typeof(String), typeof(ValidationBehavior), new PropertyMetadata(null, validationErrorChanged));

       private static void validationErrorChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
       {
           if ((d as ValidationBehavior).AssociatedObject != null)
           {
               (d as ValidationBehavior).UpdateValidationError();
           }
       }

       protected override void OnAttached()
       {
           base.OnAttached();

           UpdateValidationError();
       }

       void UpdateValidationError()
       {
           if (ValidationError == null)
               AssociatedObject.ChangeValidationState(ValidationState.NotValidated, "");
           else
               AssociatedObject.ChangeValidationState(ValidationState.Invalid, ValidationError);
       }
   }

My xaml is:

<StackPanel
      x:Name="ContentPanel"
      Grid.Row="1"
      Margin="12,0,12,0">

      <telerikPrimitives:RadTextBox
          x:Name="text1" />
      <telerikPrimitives:RadTextBox
          x:Name="text2">
          <i:Interaction.Behaviors>
              <local:ValidationBehavior
                  ValidationError="Error" />
          </i:Interaction.Behaviors>

      </telerikPrimitives:RadTextBox>

  </StackPanel>

To textbox1 I set validationState in codebehind, textbox2 has set throw behavior. But result is different, see screenshots.
No error messages showed, but focus state is correct.

[Matej]

Is this bug in your control or in my code? (it is WP8.0 Silverlight project and controls are in version 2014.2.617.3040)

[Tsvyatko]

Hello Matej,

it seems that using beahvior results in scenario in which ValidationState is set before the item is loaded. To avoid that you can modify OnAttached method in the following way:

protected override void OnAttached()
{
    base.OnAttached();

    this.AssociatedObject.Loaded += (s, e) => this.UpdateValidationError();
}

As this does not seems to be expected behavior we will log this as bug and look for solution to support the scenario without the code proposed.

Thank you for bringing your attention into this. I have updated your telerik points accordingly.

Regards,
Tsvyatko
Telerik