Angular / Isolated nested form

isolate-form.directive.js

// credits to: http://jsfiddle.net/gikoo/eLv95st4
'use strict';

angular.module('m.isolate.form')

  .directive('isolateForm', [function () {
    return {
        restrict: 'A',
        require: '?form',
        link: function (scope, elm, attrs, ctrl) {
            if (!ctrl) {
                return;
            }

            // Do a copy of the controller
            var ctrlCopy = {};
            angular.copy(ctrl, ctrlCopy);

            // Get the parent of the form
            var parent = elm.parent().controller('form');
            // Remove parent link to the controller
            parent.$removeControl(ctrl);

            // Replace form controller with a "isolated form"
            var isolatedFormCtrl = {
                $setValidity: function (validationToken, isValid, control) {
                    ctrlCopy.$setValidity(validationToken, isValid, control);
                    parent.$setValidity(validationToken, true, ctrl);
                },
                $setDirty: function () {
                    elm.removeClass('ng-pristine').addClass('ng-dirty');
                    ctrl.$dirty = true;
                    ctrl.$pristine = false;
                },
            };
            angular.extend(ctrl, isolatedFormCtrl);
        }
    };
}]);