CODEWITHSUNDEEP
c#wpfvalidationxamlcontroltemplate
Faure Ugo
Faure Ugo

Reputation: 69

Change the default ValidationRule error behavior of a TextBox

I created a custom ControlTemplate for my TextBoxes and I can't manage to override the default behaviour of the ValidationRule errors.

The TextBox border just turn red and i can't find where to override this. The thing i'd like to to in my ControlTemplate is something like this : 

<EventSetter Event="HasError" Handler="TextBox_HasErrors"/>

And in my code behind :

private void TextBox_HasErrors(...)
{
  //Change few things in my TextBox
}

As I Overrided the default ControlTemplate of the TextBox, i have this ScrollViewer x:Name="PART_ContentHost" which I think is responsible for the border coloration, but i don't know how and where to change that

Actually my usage of the textBox is like this :

<TextBox Tag="Email">
  <TextBox.Text>
    <Binding Path="Email" UpdateSourceTrigger="LostFocus">
      <Binding.ValidationRules>
        <local:TextBoxEmailValidationRule Domain=".com"/>
      </Binding.ValidationRules>
    </Binding>
  </TextBox.Text>
</TextBox>

Does some one know how i could change the red border behavior ?

Upvotes: 1

Views: 500

Answers (1)

mm8
mm8

Reputation: 169160

The red border is defined in the default Validation.ErrorTemplate of the control. You can easily create your own error template by setting the attached property to a custom ControlTemplate:

<TextBox Tag="Email">
    <TextBox.Text>
        <Binding Path="Email" UpdateSourceTrigger="LostFocus">
            <Binding.ValidationRules>
                <local:TextBoxEmailValidationRule Domain=".com"/>
            </Binding.ValidationRules>
        </Binding>
    </TextBox.Text>
    <Validation.ErrorTemplate>
        <ControlTemplate>
            <StackPanel>
                <!-- Placeholder for the TextBox itself -->
                <AdornedElementPlaceholder x:Name="textBox"/>
                <TextBlock Text="{Binding [0].ErrorContent}" Foreground="Red"/>
            </StackPanel>
        </ControlTemplate>
    </Validation.ErrorTemplate>
</TextBox>

Please refer to this blog post for more information about this and data validation in WPF in general.

Upvotes: 3

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