Angularjs select with additional option - angularjs

Question

I have a multiple select that is connectted to the model. I would like to add an additional option that's not part of the model and handle the click event. Is that possible and how?
Language:
<select multiple name="Language_Custom"
ng-model="model.Language_Custom"
ng-required="true"
ng-options="pn.Value as pn.Label for pn in Language_Custom_PossibleValues">
</select>

Answer 1

Create a function that returns a copy of your Language_Custom_PossibleValues array and appends your additional option to it. This lets you add an option without changing the underlying model.
$scope.getLanguages = function(){
var languages = [];
angular.forEach($scope.Language_Custom_PossibleValues, function(item){
languages.push(item);
});
languages.push({Value: 0, Label: 'Extra Option'});
return languages;
}
Now use that function as the source in the ng-options:
Language:<select multiple name="Language_Custom"
ng-model="model.Language_Custom"
ng-required="true"
ng-options="pn.Value as pn.Label for pn in getLanguages()"
ng-change="changeLanguage()"></select>
You also need a changeLanguage function that is called when the selected item in the list changes:
$scope.changeLanguage = function(){
if($scope.model.Language_Custom.indexOf(0) > -1)
alert('do somthing here');
}
Plunker

Answer 2

Here is the solution I used:
<div>
Language:<select multiple name="Language_Custom" ng-model="model.Language_Custom" ng-required="true">
<option ng-click="selectAllMultiValues(model, 'Language_Custom', Language_Custom_PossibleValues)">Select All</option>
<option ng-repeat="pn in Language_Custom_PossibleValues" ng-model="p.Value">{{pn.Label}}</option>
</select>
</div>