title: AngularJS ngSubmit only dirty fields
body: <p>I was wondering if there is a way to submit the form with only <code>$dirty</code> fields, currently I am using <code>ng-change</code> to manually add every field to the request on change. But the problem with that is, its not very reusable.</p>
  
  <p>in form.html</p>
  
  <pre><code>&lt;input name="status" id="status" ng-model="campaign.status" ng-change="change('status')"&gt;
  </code></pre>
  
  <p>in controller.js</p>
  
  <pre><code>$scope.updates = {};
  $scope.change = function (field) {
      $scope.updates[field] = $scope.campaign[field];
  };
  Campaign.update({id: $scope.campaign.id}, $scope.updates).$promise.then(function () {
      // success
  }, function () {
      //error
  });
  </code></pre>
  
  <p>I am looking for a better way to do this, maybe for example without the <code>updates</code> variable.</p>