Preserve empty field in model with Angular - angularjs

Question

If I have an angular form like this
<form name="myForm">
<input type="text" required ng-model="field1" />
<input type="text" ng-model="field2" />
</form>
When I access the model it will only hold those fields that have values so if both fields have values json will be {"field1":"value1","field2":"value2"}. If only field1 is has a value json will be {"field1":"value1"}. Can I instruct Angular to keep empty fields in the model with null values?
UPDATE:
My controller looks like below. I'm loading the data as json from the server. When the data comes from the server I get this {"field1":"value1","field2":"value2"} but when saveContent is run and only field1 has a value the server gets this {"field1":"value1"}.
var myApp = angular.module('myApp', []);
myApp.controller('contentEditController', ['$scope', '$http',
function ($scope, $http) {
$scope.saveContent = function () {
$http.post("/api/ContentData", $scope.formdata);
};
$scope.loadContent = function (contentId) {
$http.get("/api/ContentData/" + contentId)
.success(function (response) {
$scope.formdata = response;
});
}
}]);
So fields that had values when they came from the server don't get sent back as empty.
-Mathias

Answer 1

Initialize the values on the scope in the controller,
.controller('formcontroller', [ '$scope', function($scope){
$scope.field1 = "";
$scope.field2 = "";
})];

Answer 2

The proper way to do this is to initialize the variables. You should in your controller have
$scope.field1 = ""
$scope.field2 = ""
or a more crude way to do is in to use ng-init (try not to use ng-init if you can)
<input type="text" required ng-model="field1" ng-init="field1=''"/>
<input type="text" ng-model="field2" ng-init="field2=''"/>