title: CakePHP Validation depending on other field
body: <p>I wonder if it is possible with CakePHP validation rules to validate a field depending on another.</p>
  
  <p>I have been reading the <a href="http://book.cakephp.org/2.0/en/models/data-validation.html#adding-your-own-validation-methods" rel="noreferrer">documentation about custom validation rules</a> but the <code>$check</code> param only contains the value of the current field to validate.</p>
  
  <p>For example. I would like to define the <strong>verify_password</strong> field as <em>required</em> <strong>only if</strong> the <strong>new_password</strong> field is not empty. (in case </p>
  
  <p>I could do it with Javascript anyway but i wonder if it is possible to do it directly with CakePHP.</p>