templatedUrl中ng-model中的值更改在指令中未定义

Question

最初当我加载它工作正常，但是当我更改模板URl中的值为ng-model scope.value在我的链接中是未定义的。我正在为datepicker bootstrap angularjs制作指令。

dateTime .directive("DatePicker", function(){

             return {
                        restrict: "E",
                        transclude: true,
                        require: "ngModel",
                        scope:{
                            ngModel: "=",
                            dateOptions: "=",
                            opened: "="
                        },

                        link: function($scope, element, attrs, datepickerModel) {

                            $scope.open = function(event){
                                event.preventDefault();
                                event.stopPropagation();
                                $scope.opened = true;
                            };

                            $scope.myModel = new Date();
                            datepickerModel.$setViewValue($scope.myModel);

                            $scope.$watch('myModel',function(){
                                console.log("value changed"+$scope.myModel);
                                datepickerModel.$setViewValue($scope.myModel);
                                console.log($scope.myModel);
                            })

                        template: ' <input type="date" class="form-control" datepicker-popup="{{format}}" ng-model="myModel" is-open="opened" min-date="minDate" max-date="'2015-06-22'" datepicker-options="dateOptions" date-disabled="disabled(date, mode)" ng-required="true" close-text="Close" />'
                    }
                })