title: AngularJS $scope.$watch properties of $scope.foo but send old values to server before change
body: <p>I have an object $scope.foo in my controller.  I want to watch for any changes in $scope.foo.bar and $scope.foo.baz and do a get request and replace all the data in $scope.foo object.  Before this change happens, I would like to send the data of $scope.foo to the server with the old $scope.foo.bar and $scope.foo.baz.</p>
  
  <pre><code>$scope.$watch('foo.bar + form.baz', function() {
      // send old $scope.foo to server with the 
      // previous $scope.foo.bar and $scope.foo.baz
  });
  </code></pre>
  
  <p>How would I go about doing this? TIA</p>