title: How do I force Angular to run a validation cycle (for built in validation)?
body: <p>I need to <strong>update the model</strong> of a text field, then <strong>fire validation</strong> to show the user visual feedback that it is a valid entry.</p>
  
  <p>I have tried two methods, but I can only get one of the requirements to work at the expense of the other.</p>
  
  <p><strong>First option</strong>: <a href="http://jsfiddle.net/TZQjS/" rel="nofollow">http://jsfiddle.net/TZQjS/</a></p>
  
  <pre>
    // changing the model in controller updates the field
    // but the `required` directive will not run.
    $scope.populateValid = function () {
       $scope.testField = 'yes, yes, yes';
    }
  </pre>
  
  <p><strong>Second option</strong>:<a href="http://jsfiddle.net/R3b7Y/" rel="nofollow">http://jsfiddle.net/R3b7Y/</a></p>
  
  <pre>
    // `$setViewValue()` of the ngModel API updates the model 
    // but two-way binding seems to fail
    $scope.populateValid = function () {
       $scope.testForm.testField.$setViewValue('yes, yes, yes');
    }
  </pre>
  
  <p>How can I make both things happen, that is update the field with text, and also run validation immediately after?</p>
  
  <p>I have read in places of <code>$parsers</code> and <code>$formatters</code> but I cannot understand how to use them in this context - many discussions talk about them in terms of custom validation directives.</p>