ng-model: empty strings should be null

Question

If I use ng-model for an input field and empty it, angular sets it to \'\' instead of null even if it was null before.

Answer 1

You may want to $watch for the empty value and set it to null:

<input type="text" ng-model="test.value" />

$scope.$watch('test.value', function (newValue, oldValue) {
  if(newValue === "")
    $scope.test.value = null;
});

Another way would be to use a custom directive and apply a $parsers in it:

<input type="text" ng-model="test.value" empty-to-null />

myApp.directive('emptyToNull', function () {
    return {
        restrict: 'A',
        require: 'ngModel',
        link: function (scope, elem, attrs, ctrl) {
            ctrl.$parsers.push(function(viewValue) {
                if(viewValue === "") {
                    return null;
                }
                return viewValue;
            });
        }
    };
});