How to pass the binding path to DataTrigger in a WPF style? - wpf

Question

I've several style with only a little difference in binding path:
<Style TargetType="FrameworkElement" x:Key="FieldValidationErrorStyle">
<Setter Property="Visibility" Value="Visible" />
<Style.Triggers>
<DataTrigger Binding="{Binding Path=FieldValidationError}" Value="">
<Setter Property="Visibility" Value="Collapsed" />
</DataTrigger>
</Style.Triggers>
</Style>
<Style TargetType="FrameworkElement" x:Key="NumberValidationErrorStyle">
<Setter Property="Visibility" Value="Visible" />
<Style.Triggers>
<DataTrigger Binding="{Binding Path=NumberValidationError}" Value="">
<Setter Property="Visibility" Value="Collapsed" />
</DataTrigger>
</Style.Triggers>
</Style>
<Style TargetType="FrameworkElement" x:Key="TextValidationErrorStyle">
<Setter Property="Visibility" Value="Visible" />
<Style.Triggers>
<DataTrigger Binding="{Binding Path=TextValidationError}" Value="">
<Setter Property="Visibility" Value="Collapsed" />
</DataTrigger>
</Style.Triggers>
</Style>
<Style TargetType="FrameworkElement" x:Key="DateTimeValidationErrorStyle">
<Setter Property="Visibility" Value="Visible" />
<Style.Triggers>
<DataTrigger Binding="{Binding Path=DateTimeValidationError}" Value="">
<Setter Property="Visibility" Value="Collapsed" />
</DataTrigger>
</Style.Triggers>
</Style>
<Style TargetType="FrameworkElement" x:Key="DateValidationErrorStyle">
<Setter Property="Visibility" Value="Visible" />
<Style.Triggers>
<DataTrigger Binding="{Binding Path=DateValidationError}" Value="">
<Setter Property="Visibility" Value="Collapsed" />
</DataTrigger>
</Style.Triggers>
</Style>
<Style TargetType="FrameworkElement" x:Key="TimeValidationErrorStyle">
<Setter Property="Visibility" Value="Visible" />
<Style.Triggers>
<DataTrigger Binding="{Binding Path=TimeValidationError}" Value="">
<Setter Property="Visibility" Value="Collapsed" />
</DataTrigger>
</Style.Triggers>
</Style>
We can find the only difference between the styles is the {Binding Path=xyz} in DataTrigger, can I remove the duplication with only XMAL markup? I know we can create custom styles as in this question but the setters are hard coded - can we only extend DataTrigger?

Answer 1

You can use a single style with a MultiBinding DataTrigger and an OR Converter in it.
<Window.Resources>
<local:AtleastOneEmptyConverter x:Key="AtleastOneEmptyConverter"/>
<Style TargetType="{x:Type FrameworkElement}">
<Setter Property="Visibility" Value="Visible" />
<Style.Triggers>
<DataTrigger Value="True">
<DataTrigger.Binding>
<MultiBinding
Converter="{StaticResource AtleastOneEmptyConverter}">
<Binding Path="FieldValidationError"/>
<Binding Path="NumberValidationError"/>
<Binding Path="TextValidationError"/>
...
<Binding Path="DateTimeValidationError"/>
</MultiBinding>
</DataTrigger.Binding>
<Setter Property="Visibility" Value="Collapsed"/>
</DataTrigger>
</Style.Triggers>
</Style>
</Window.Resources>
Code Behind:
public class AtleastOneEmptyConverter : IMultiValueConverter
{
public object Convert(object[] values, Type targetType,
object parameter, CultureInfo culture)
{
return values.Cast<string>().Any(p => string.IsNullOrEmpty(p));
}
public object[] ConvertBack(object value, Type[] targetTypes,
object parameter, CultureInfo culture)
{
throw new NotImplementedException();
}
}
I do suggest, to skip applying styles to all framework elements in your application. It can make your application GUI slow if it grows complex in the future and seek an alternate approach such as Validation Model of WPF.
If you still want to apply style to all types of framework elemetns in your application then you can alternately explore App.xaml way to override styles of all framework elements in your application...

Answer 2

Seems like you want to create a template for a DataTrigger. Since you can't style DataTriggers, you have to resort to creating your own:
public class CollapsingDataTrigger : DataTrigger
{
public CollapsingDataTrigger()
{
base.Setters.Add(new Setter(FrameworkElement.VisibilityProperty, Visibility.Collapsed));
}
}
Then update your XAML to use this CollapsingDataTrigger instead of the regular one(you will have to reference the namespace this is created in).