AngularJS $watch not working in if-block

Question

I figured out, that my angular script is working:

$scope.CurrentUser = null;
$scope.DatePicker = new Date();
$scope.$watch('DatePicker', function (newValue, oldValue) {
    if (newValue > new Date())
        $scope.DatePicker = new Date();
}, true);

<div>
    <input data-ng-model="DatePicker" type="date" id="datepicker" />
</div>

but not if I add an if-statment:

<div data-ng-if="!CurrentUser">
    <input data-ng-model="DatePicker" type="date" id="datepicker" />
</div>

Try it: http://codepen.io/anon/pen/jWBEVM

But I don't understand why. Is there a known issue? Can anybody help?

Answer 1

from doc

This directive creates new scope.

so, in your case

<div data-ng-if="!CurrentUser">
    <input data-ng-model="DatePicker" type="date" id="datepicker" />
</div>

DatePicker here added in ng-if scope and not scope from controller.

for solving, you can use $parent property

<div data-ng-if="!CurrentUser">
    <input data-ng-model="$parent.DatePicker" type="date" id="datepicker" />
</div>

Or apply "dot rule"

<div data-ng-if="!CurrentUser">
    <input data-ng-model="data.DatePicker" type="date" id="datepicker" />
</div>

and in js

$scope.data = { DatePicker : new Date() };
$scope.$watch('data.DatePicker', function (newValue, oldValue) {
...

See a bit more about inheritance scope in wiki

Sample

var app = angular.module('myApp', []);

app.controller('BodyCtrl', function($scope, $http) {
  $scope.CurrentUser = null;
  $scope.DatePicker = new Date();
  $scope.data = { DatePicker : new Date() } ;
  $scope.$watch('DatePicker', function(newValue, oldValue) {
    if (newValue > new Date())
      $scope.DatePicker = new Date();
  }, true);
  $scope.$watch('data.DatePicker', function(newValue, oldValue) {
    if (newValue > new Date())
      $scope.data.DatePicker = new Date();
  }, true);

});

<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.4.7/angular.min.js"></script>
<div data-ng-app="myApp" data-ng-controller="BodyCtrl">
  <div>
    <span>scope id: {{$id}}</span>
    <input data-ng-model="DatePicker" type="date" id="datepicker" />
  </div>
  <div data-ng-if="!CurrentUser">
    <span>scope id: {{$id}}</span>
    <input data-ng-model="DatePicker" type="date"  />
  </div>
  <div data-ng-if="!CurrentUser">
    <span>scope id: {{$id}}</span>
    <input data-ng-model="$parent.DatePicker" type="date" />
  </div>
  <hr/>
  <div>
    <span>scope id: {{$id}}</span>
    <input data-ng-model="data.DatePicker" type="date" />
  </div>
  <div data-ng-if="!CurrentUser">
    <span>scope id: {{$id}}</span>
    <input data-ng-model="data.DatePicker" type="date"  />
  </div>
  
</div>