Validation Rule for Radio buttons wpf

I have a RadioButton inside ItemsControl. By default Radio Buttons will be unchecked. I want the user to select either of the radio buttons if a particular value (string value) is configured in another screen. I need to apply a validation rule for the same. If the user does not select either of the radio buttons, then on click on a submit button, I should display validation error.

XAML

<StackPanel Grid.Row="1" Visibility="{Binding Path=IsUpdateSendDateConfigured}" Orientation="Horizontal" Margin="0,2,0,0">
        <TextBlock Text="{Binding Path=UpdateSendDate, UpdateSourceTrigger=PropertyChanged}" FontWeight="Bold" FontSize="12" Width="400" TextWrapping="WrapWithOverflow" />
        <ItemsControl Name="updateSendDateLevelItemsControl" ItemsSource="{Binding UpdateSendDateLevel}" Margin="10,5,0,10">
                 <ItemsControl.ItemsPanel>
                         <ItemsPanelTemplate>
                                <StackPanel Orientation="Horizontal"/>
                         </ItemsPanelTemplate>
                 </ItemsControl.ItemsPanel>
                 <ItemsControl.ItemTemplate>
                         <DataTemplate>
                                <RadioButton Height="25" GroupName="updateSendDateLevel" IsChecked="{Binding Selected, ValidatesOnDataErrors=True}" Padding="10,0,10,0" >  <!--Need to apply Validation rule here -->
                                       <TextBlock Text="{Binding Description}"/>
                                </RadioButton>
                         </DataTemplate>
                  </ItemsControl.ItemTemplate>
        </ItemsControl>
</StackPanel>

UpdateSendDateLevel is a view model which I am updating in the controller.

if (!string.IsNullOrEmpty(configuredUpdateDueDateSelection))
{
       UpdateSendDateViewModel updateSendDateLevelViewModel = null;
       foreach (SendDate value in Enum.GetValues(typeof(SendDate)).Cast<SendDate>())
       {
             updateSendDateLevelViewModel = new UpdateSendDateViewModel();
             updateSendDateLevelViewModel.UpdateSendDateLevel = value;
             updateSendDateLevelViewModel.Description = EnumHelper.GetDescription(value);

             m_sendDataContext.UpdateSendDateLevel.Add(updateSendDateLevelViewModel);
        }

}

Can someone please help with with adding xaml side validation rule or point me in the right direction?

Let me know if you need any other details.

ValidationRules can be added as an extension of the Binding property, like so:

<RadioButton>
    <TextBlock Text="{Binding Description}"/>
    <RadioButton.IsChecked>
        <Binding Path="Selected" UpdateSourceTrigger="PropertyChanged">
          <Binding.ValidationRules>
            <rules:YourValidationRule Min="21" Max="130"/>
          </Binding.ValidationRules>
        </Binding>
    </RadioButton.IsChecked>
</RadioButton>

(Note for the above that you don't actually need to use a TextBlock if all you're doing is putting text in the block. You can just include that text binding in the Content="" field on the RadioButton.)

Then you'd also need to define an object (YourValidationRule) that inherits from ValidationRule and overrides public ValidationResult Validate(object value, CultureInfo cultureInfo), and add a static reference (rules, in this case) to the namespace in which your custom ValidationRule exists.

An in-depth tutorial for ValidationRules exists on MSDN at this link: http://msdn.microsoft.com/en-us/library/ms753962%28v=vs.110%29.aspx

However, Miiko is correct - it may be easier for you to use an object that implements ICommand, and use CanExecute to determine whether the customer may proceed. The main downside of this is that a ghosted, unusable button is not necessarily communicative, and you should be careful to ensure that your customers understand why they're unable to use the button.