title: How to fire a custom event to trigger partial form validation?
body: <p>Iam trying to validate my form step by step on clicking a button called 'next'.
  Is there a way to fire a custom event to trigger partial form validation?
  Something like that:</p>
  
  <pre><code>&lt;input type="text" id="age-id" name="age" 
    ng-model-options="{updateOn: 'ValidateStepOne'}" 
    min="18"
    max="99"
    ng-model="data.age"
  &gt;
  </code></pre>
  
  <p>Triggering the event onclick at a button:</p>
  
  <pre><code>$scope.validate = function() {
      $rootScope.$broadcast('ValidateStepOne');
  };
  </code></pre>
  
  <p>Any help would be kindly appreciated.
  Kind regards</p>
  
  <p>OliverKK</p>