Question

In my WPF application, I want to set NotifyOnValidationError to true (the framework defaults it to false) for all child controls/bindings if they have any ValidationRules attached to the binding. Indeed, it would be nice to specify other binding defaults too – e.g. ValidatesOnDataErrors should also always be true.

For example, in the following text box I don’t want to have to manually specify the NotifyOnValidationError property.

<TextBox>
    <TextBox.Text>
        <Binding Path="PostalCode" 
                 ValidatesOnDataErrors="True" 
                 NotifyOnValidationError="True">
            <Binding.ValidationRules>
                <rules:PostalCodeRule />
            </Binding.ValidationRules>
        </Binding>
    </TextBox.Text>
</TextBox>

Answer 1

Since Binding is just a markup extension you could create a custom Markup Extensions that extends Binding and sets those properties to your desired defaults.