title: Symfony2 Validator Constraint GreaterThan on other property
body: <p>My validations are defined in a yaml file like so;  </p>
  
  <pre><code># src/My/Bundle/Resources/config/validation.yml
  My\Bundle\Model\Foo:
      properties:
          id:
              - NotBlank: 
                  groups: [add]
          min_time:
              - Range:
                  min: 0
                  max: 99
                  minMessage: "Min time must be greater than {{ limit }}"
                  maxMessage: "Min time must be less than {{ limit }}"
                  groups: [add]
          max_time:
              - GreaterThan:
                  value: min_time
                  groups: [add]
  </code></pre>
  
  <p>How do I use the validator constraint <code>GreaterThan</code> to check against another property?<br>
  E.g make sure max_time is greater than min_time?</p>
  
  <p>I know I can create a custom constraint validator, but surely you can do it using the <code>GreaterThan</code> constraint.<br>
  Hopefully I am missing something really simple here</p>