Angular how to have multiple selected - angularjs

Question

I have this array of objects. that holds somethings like this.
[
{
id: 1,
name: "Extra Cheese"
},
{
id: 2,
name: "No Cheese"
}
]
im iterating thru the array here
<select ng-model="item.modifiers" multiple chosen class="chosen-select" tabindex="4" ng-options="modifier._id as modifier.name for modifier in modifiers"></select>
The thing item.modifiers model that has an array of this 2 id
[
1,2
]
I want the multi select to auto selected the two ids that are in the item.model
I want the final result to look something like this

Answer 1

Your code is pretty much working already, maybe some of the variables are not assigned correctly (eg. id instead of _id)
angular.module('test', []).controller('Test', Test);
function Test($scope) {
$scope.modifiers = [
{
id: 1,
name: "Extra Cheese"
},
{
id: 2,
name: "No Cheese"
}
]
$scope.item = {};
// add this for pre-selecting both options
$scope.item.modifiers = [1,2];
}
<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.5.8/angular.min.js"></script>
<div ng-app='test' ng-controller='Test'>
<select ng-model="item.modifiers" multiple chosen class="chosen-select" tabindex="4" ng-options="modifier.id as modifier.name for modifier in modifiers"></select>
</div>

Answer 2

If I understand the question correctly, you're wanting to pre-select the two options.
To do this you will need to set your ng-model to point to the actual objects you are iterating over.
You will also need to change your ng-options to ng-options="modifier as modifier.name for modifier in modifiers" rather than just iterating over the ids.
Here's the relevant documentation under Complex Models (objects or collections)
https://docs.angularjs.org/api/ng/directive/ngOptions
Something like this should work:
HTML:
<select ng-model="$ctrl.item.modifiers"
ng-options="modifier as modifier.name for modifier in $ctrl.modifiers"
multiple chosen class="chosen-select" tabindex="4" >
</select>
JS:
app.controller("my-controller", function() {
var $ctrl = this;
$ctrl.modifiers = [{
id: 1,
name: "Extra Cheese"
}, {
id: 2,
name: "No Cheese"
}];
$ctrl.item = {
modifiers: []
}
$ctrl.$onInit = function() {
const id1 = 1;
const id2 = 2;
for (const modifier of $ctrl.modifiers) {
if (modifier.id === id1 || modifier.id === id2) {
$ctrl.item.modifiers.push(modifier);
}
}
}
}
Here's a pen showing the result:
http://codepen.io/Lahikainen/pen/WooaEx
I hope this helps...