AngularJS Select Not Binding To Ng-Model - angularjs

Question

My angular select isn't binding. I can tell the value is correct, but the select isn't updated. Why is not binding if the value is there?
<div ng-controller="MyController" ng-app>
<select class="form-control" ng-model="colorId"ng-options="color.id as color.name for color in colorList">
<option value="">--Select a Color--</option>
</select>
<input type="button" value="submit" ng-click="Select()"></input>
function MyController($scope) {
$scope.colorList = [{
id: '1',
name: 'red'
}, {
id: '2',
name: 'blue'
}, {
id: '3',
name: 'green'
}];
var colorId = 3;
$scope.colorId = colorId;
alert($scope.colorId);
$scope.Select = function () {
var colorId = 2;
$scope.colorId = colorId;
}
}
Here is a fiddle:
http://jsfiddle.net/ky5F4/23/

Answer 1

you need to change the id to a string when doing Select
$scope.Select = function () {
console.log('select fired');
var colorId = 1;
$scope.mySelection.colorId = colorId + "";
}
http://jsfiddle.net/bxkwfo0s/2/
next you should use a property of an object rather than just a scope variable, this will ensure proper model binding
ng-model="mySelection.colorId"
where the object could be something simple
$scope.mySelection = {colorId : colorId };

Answer 2

There are two errors with your code:
You are using colorList as your model in ng-options, but you are calling it datasets in your controller.
You use strings for the id, but set the $scope.colorId to a number.
Here is an updated fiddle changing ids to numbers and changing $scope.datasets to $scope.colorList
function MyController($scope) {
$scope.colorList = [{
id: 1,
name: 'red'
}, {
id: 2,
name: 'blue'
}, {
id: 3,
name: 'green'
}];
var colorId = 3;
$scope.colorId = colorId;
alert($scope.colorId);
$scope.Select = function () {
var colorId = 2;
$scope.colorId = colorId;
}
}

Answer 3

Consider making your ng-model be an object, specifically one of the objects that are already in your $scope.colorList. If you do that you should be able to avoid the post-processing you're doing in the click handler.
So your select will look like this:
<select class="form-control" ng-model="selectedColor"
ng-options="color.name for color in colorList"></select>
One gotcha is that if you have an object in your controller that looks JUST LIKE your red object, like$scope.selectedColorObj = { id : '1', name:'red' } and set the select's ng-model to that option, it won't work. Angular will see that you're setting to the ng-model to an object that's not actually in your data source and add an extra option with value="?", so I use $filter in this case to grab the matching member of the array:
$scope.colorId = '3';
$scope.selectedColor = $filter('filter')( $scope.colorList,{ id: $scope.colorId})[0];
See http://jsfiddle.net/ky5F4/92/