如何使用angularjs ng-options和ng-model使用strict设置所选选项？

Question

一切都很好，并且我在模型中设置了默认值，但似乎只是不想将其用作select元素中的默认选项。 如何完成获取模型以选择相应的语言iso值的操作？ 另外，如何避免将空选项添加到选择中？

示例数据：

// list of languages
[
 {"iso":"abk","language":"Abkhazian"},
 {"iso":"aar","language":"Afar"},
 {"iso":"afr","language":"Afrikaans"},
  ...
]

// location object containing the property for the language value
{
    "id":"516",
    "site":"Al Seela",
    "start_utc":"03:00:00",
    "end_utc":"06:00:00",
    ...
    "lang_iso":"eng",
    "language":"English"
}

标记：

<div ng-controller="StationListController as stationList" ng-init="init()">
    ...
    <div ng-repeat="location in station.locations" class="panel panel-default">
    ...
        <select class="form-control" id="{{'locationLang-' + location.id}}" ng-model="location.lang_iso" ng-options="lang.iso as lang.language for lang in locLanguages track by lang.iso"></select>

JS：

$scope.init = function () {
    $http.get($scope.ajaxurl + '?_mode=languages&_task=list').success(function(data, success) {
        $scope.locLanguages = data;
    }).error(function(error) {});
};

结果：

<select ng-options="lang.iso as lang.language for lang in locLanguages track by lang.iso" ng-model="location.lang_iso" id="locationLang-844" class="form-control ng-pristine ng-valid ng-touched">
    <option value="?" selected="selected"></option>
    <option value="abk" label="Abkhazian">Abkhazian</option>
    <option value="aar" label="Afar">Afar</option>
    <option value="afr" label="Afrikaans">Afrikaans</option>
    ...
</select>

Answer 1

解决空选项问题的唯一方法是在控制器中分配一个默认值。 如今，仅使用第一个值是非常标准的，因此只需将$scope.init更新为：

$scope.init = function () {
    $http.get($scope.ajaxurl + '?_mode=languages&_task=list').success(function(data, success) {
        $scope.locLanguages = data;
        $scope.location.lang_iso = {"iso":"abk","language":"Abkhazian"}; // or perhaps the entire object
    }).error(function(error) {});
};