title: Yii form model validation- either one is required
body: <p>I have two fields on the form ( forgotpassword form ) username and email Id . User should enter one of them .  I mean to retrieve the password user can enter user name or the email id  . Could some one point me the validation rule for this ?</p>
  
  <p>Is there any inbuilt rule I can use ?</p>
  
  <p>( Sorry if it is already discussed or if I missed)</p>
  
  <p>Thanks for your help</p>
  
  <p>Regards</p>
  
  <p>Kiran</p>