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Attached DependencyProperty and generic styles

Posted By:      Posted Date: October 28, 2010    Points: 0   Category :WPF

Hi All,

I created an attached dependency property, let's say "MyProperty.MyAttachedDependencyProperty".
When I use this attached dependency properties straight on a control, everything works fine.

For instance:


<TextBox MyProperty.MyAttachedDependencyProperty="True" Text="SomeText" />


Now, I want to assign this value for my attached dependency property in a style.
I know it should be possible to set values for attached dependency properties in style, because for instance
the System.Windows.Controls.Validation.ErrorTemplate attached dependency property can be set in style as well.

So I create my style like this:

<Style x:Key="MyStyle" TargetType="{x:Type TextBox}">
  <Setter Property="MyProperty.MyAttachedDependencyProperty" Value="True"/>


<TextBox Style="{StaticResource MyStyle}" Text="SomeText" />



Then I get an exception saying:

'Set property 'System.Windows.Setter.Property' threw an exception.' Line number '46' and line position '14'.
"Value cannot be null.\r\nParameter name: property"

   at System.Win

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