多个ListBoxField用于预定义列表

Question

我有一个地址DataObject：

class Address extends DataObject{
    private static $db = array(
        'Address'       => 'varchar(255)',
    );

    private static $many_many = array(
        'Countries' => 'Country'
    );

    public function getCMSFields() {
        $fields = FieldList::create(TabSet::create('Root'));
        $fields->addFieldsToTab('Root.Main', array(
            TextField::create('Name'),
            ListBoxField::create('Countries', 'Countries')->setMultiple(true)->setSource(Country::get()->map('ID', 'Name'))
        ));
        return $fields;
    }
}

国家dataObject：

class Country extends DataObject{

    private static $belongs_many_many = array(
        'Addresses' => 'Address',
    );

    private static $countries = array(
        "AF"    => array("Name"=>"Afghanistan","PhoneExtension"=>"+93"),...
    );
    public static function get($callerClass = null, $filter = "", $sort = "", $join = "", $limit = null, $containerClass = 'DataList') {            $return = new ArrayList();
        $i = 1; //if I do 0 it always populates the admin field.
        foreach (self::$countries as $key => $value) {
            $return->add(new ArrayData(array('ID' => $i, 'Acronym' => $key, 'Name' => $value['Name'])));
            $i++;
        }
        return $return;
    }
}

**更新**

在数据库中，这会正确保存，但它无法在CMS管理员中正确返回。我错过了什么？