Wpf TextBox style with tooltip - wpf

Question

I want my text boxes to show a specific text as tool tip depending on the validation status. To do this I currently use the following code and it works:
<TextBox Name="textBox1">
<TextBox.Style>
<Style TargetType="{x:Type TextBox}">
<Style.Triggers>
<Trigger Property="Validation.HasError" Value="False">
<Setter Property="ToolTip" Value="{Binding XPath=HelpText/Description, Mode=OneTime}" />
</Trigger>
<Trigger Property="Validation.HasError" Value="True">
<Setter Property="ToolTip" Value="{Binding RelativeSource={x:Static RelativeSource.Self}, Path=(Validation.Errors)[0].ErrorContent}" />
</Trigger>
</Style.Triggers>
</Style>
</TextBox.Style>
</TextBox>
When there is no error, a description text read from an xml-file is displayed and when there is an error the validation error string is displayed.
The problem is that now I have to copy this style and apply it to every textbox (and change the XPath, it is unique for each text box), what I would want to do is put the style in Window.Resources so that I can just reference it for every text box like this:
<TextBox Name="textBox2" Style="{StaticResource TextBoxStyle}" />
But the XPath will be different for each textbox so I cannot just place my style in Window.Resources. How can I make an instance specific XPath available in the style? Is there a way to do this without creating a new text box and derive from TextBox? I was wondering if one could use an attached property in this case but I don't know how they work.
Thanks in advance.

Answer 1

I haven't completely tested this, but you could use an attached property
Something like:
class ToolTipHelper {
public static readonly DependencyProperty ToolTipProperty =
DependencyProperty.RegisterAttached("ToolTip", typeof(string) ...
Then you modify your trigger:
<Trigger Property="Validation.HasError" Value="False">
<Setter Property="ToolTip" Value="{Binding RelativeSource={RelativeSource Self}, Path=(ToolTipHelper.ToolTip}, Mode=OneTime}" />
</Trigger>
And you use it like
<TextBox ToolTipHelper.ToolTip="{Binding XPath=HelpText/Description, Mode=OneTime}" />

Answer 2

You could use the Tag Property and change your style to
<Style TargetType="{x:Type TextBox}">
<Setter Property="ToolTip" Value="{Binding RelativeSource={RelativeSource Self}, Path=Tag}" />
<Style.Triggers>
<Trigger Property="Validation.HasError" Value="True">
<Setter Property="ToolTip" Value="{Binding RelativeSource={RelativeSource Self}, Path=(Validation.Errors)[0].ErrorContent}" />
</Trigger>
</Style.Triggers>
</Style>
Then you bind the desired XPath to the Tag property of each specific TextBox
<TextBox Tag="{Binding XPath=HelpText/Description, Mode=OneTime}" />