DataBinding is not working in my Controller

I'm wondering why my DatBinding is not working.

The problem is in the function foo where the $scope.data.time is set properly but my input-value does not change. Why?

Here is the Code of my Controller:

.controller('MyCtrl', function($scope, $ionicPopup, $cordovaDatePicker) {    

    $scope.foo = function() {
        $cordovaDatePicker.show().then(function(date){
            // PROBLEM: the $scope.data is set right, but my input value does not change
            $scope.data.time = date;    
        });
    };

    $scope.showPopup = function() {
        $scope.data = {};
        $scope.data.time = new Date();

      var myPopup = $ionicPopup.show({
        template: '<input type="text" ng-click="foo()" value="{{data.time.toDateString()}}">'
        title: 'Enter new record',
        scope: $scope,
        ...
      });
     };

});