ValidationRules without binding

Question

I want to use the ValidationRules (and it's UI effects) on the textbox without actually binding anything to the textbox.

I want to use the textbox for some input that doesn't bound to anything but need to validate the input after focus is lost using the ValidationRules.

Can it be done?

<TextBox.Text>
   <Binding Path="" UpdateSourceTrigger="LostFocus">
     <Binding.ValidationRules>
        <local:IntegersOnlyValidator/>
     </Binding.ValidationRules>
   </Binding>
 </TextBox.Text>

Answer 1

This worked for me:

<TextBox.Text>
    <Binding RelativeSource="{RelativeSource Self}" Path="Text" UpdateSourceTrigger="LostFocus">
      <Binding.ValidationRules>
        <Filters:IntegersOnlyValidator/>
      </Binding.ValidationRules>
   </Binding>
 </TextBox.Text>

Answer 2

You could bind to just any string, e.g. create one as the source for the binding:

xmlns:sys="clr-namespace:System;assembly=mscorlib.dll"

  <TextBox>
    <TextBox.Text>
      <Binding Path=".">
        <Binding.Source>
          <sys:String>Default Text</sys:String>
        </Binding.Source>
        <Binding.ValidationRules>
          <!-- Validation Rules -->
        </Binding.ValidationRules>
      </Binding>
    </TextBox.Text>
  </TextBox>

Answer 3

Your code-behind should be as independent of the GUI as possible, so I would recommend you to create a property and bind to that. When you want to pass the text to the method, just pass the value of the property.