Get ValidationError in specific xaml element using a template - wpf

Question

i have the following code snippet:
<ContentControl Height="16">
<ContentControl.Style>
<Style TargetType="ContentControl">
<Style.Triggers>
<DataTrigger Binding="{Binding ElementName=txtDistanceH, Path=(Validation.HasError)}" Value="True">
<Setter Property="Content" Value="{Binding ElementName=txtDistanceH, Path=(Validation.Errors)[0]}" />
</DataTrigger>
</Style.Triggers>
</Style>
</ContentControl.Style>
</ContentControl>
Now i want to put the style in a separate file instead of inline. However i would like to be able to specify which element it should get the Validation.Errors from, so i can use a single template for several different controls.
Is there any way to tell the template where it should get the Validation.Errors from, OTHER than binding to an element by name?
I tried setting the ContentControls DataContext to the element txtDistanceH, but then i just get a binding error saying that the property cannot be found on the root-element.

Answer 1

thanks for taking the time to answer my question. I've tried it and it works!
However i do have a comment and another related question.
The code i have now is:
<!-- Set content of contentcontrol to the ValidationError of a control stored in Tag, if there is one -->
<Style x:Key="ShowValidationError" TargetType="ContentControl">
<Style.Resources>
<x:Static x:Key="EmptyString" Member="System:String.Empty" />
</Style.Resources>
<Setter Property="Content" Value="{StaticResource EmptyString}" />
<Style.Triggers>
<DataTrigger Binding="{Binding RelativeSource={RelativeSource Self}, Path=Tag.(Validation.HasError)}" Value="True">
<Setter Property="Content" Value="{Binding RelativeSource={RelativeSource Self}, Path=Tag.(Validation.Errors).CurrentItem}" />
</DataTrigger>
</Style.Triggers>
</Style>
(Validation.Errors).CurrentItem is better than (Validation.Errors)[0], because the latter gives an out of range exception in the debug window when the error is resolved, see This Link for more information. The empty string ensures the control has the same size when its empty as when it has an error.
However even though it compiles and works, i still get some errors during design time. The code responsible is (Validation.HasError) and (Validation.Errors), respectively, in the above snippet.
Property 'Errors' is not attachable to elements of type 'Object'.
The property 'HasError' was not found in type 'Validation'.
Is there any way to fix / suppress these errors?

Answer 2

Bind the Tag property of the ContentControl to the target element using the element name binding and then update the style to use relative source self bindings to the tag to get at the validation errors.
Somewhere in Resources:
<Style x:Key=“ValidationStyle” TargetType="ContentControl">
<Style.Triggers>
<DataTrigger Binding="{Binding RelativeSource={RelativeSource Self}, Path=Tag.(Validation.HasError)}" Value="True">
<Setter Property="Content" Value="{Binding RelativeSource={RelativeSource Self}, Path=Tag.(Validation.Errors)[0]}" />
</DataTrigger>
</Style.Triggers>
</Style>
And use it thusly:
<ContentControl Style=“{StaticResource ValidationStyle}” Tag=“{Binding ElementName=txtDistanceH}” />