AngularJS: Use ng-option to generate a drop-down box and call it in the controller. angularjsng-option

AngularJS: Use ng-option to generate a drop-down box and call it in the controller. angularjsng-option
Controller code

function billsDetailController($scope, $http, $log) {    var self = this;    $scope.billsDetailData = [];    $scope.billsDetailTotalData = [];    $scope.model = [{        id: 201401,        productName: '2014-01'    }, {        id: 201402,        productName: '2014-02'    }, {        id: 201403,        productName: '2014-03'    }, {        id: 201404,        productName: '2014-04'    }, {        id: 201405,        productName: '2014-05'    }, {        id: 201406,        productName: '2014-06'    }, {        id: 201407,        productName: '2014-07'    }, {        id: 201408,        productName: '2014-08'    }, {        id: 201409,        productName: '2014-09'    }, {        id: 201410,        productName: '2014-10'    }, {        id: 201411,        productName: '2014-11'    }, {        id: 201412,        productName: '2014-12'    }    ];    $scope.currentPeriod = $scope.model[0].productName;    $scope.change = function(){        self.getDetailPagedDataAsync( $scope.currentPeriod);        self.getDetailTotalData( $scope.currentPeriod);    }

HTML code

 <select id="selectError" ng-model="currentPeriod" ng-change="change()" ng-options="option.productName as option.productName for option in model"> </select>