joomla – 如何在模块中创建自定义表单字段类型？

我使用joomla 2.5,我想创建一个存储在同一模块中的自定义表单字段类型.

在XML中：

<fieldset  name="basic" addfieldpath="/modules/mod_royalslider/fields"></fields>
      <fieldset name="basic">
           <field name="title" type="City" label="anythging" description=""   />
      </fieldset>
 </fields>

在文件/modules/mod_royalslider/fields/city.php中

<?php
// check to ensure this file is included in Joomla!
defined('_jeXEC') or die('ReStricted access');

jimport('joomla.form.formfield');

class JFormFieldCity extends JFormField {

    protected $type = 'City';

    // getLabel() left out

    public function geTinput() {
            return '<SELEct id="'.$this->id.'" name="'.$this->name.'">'.
                   '<option value="1" >New York</option>'.
                   '<option value="2" >Chicago</option>'.
                   '<option value="3" >San Francisco</option>'.
                   '</SELEct>';
    }
}

现在它告诉我错误,当我删除
< fieldset name =“basic”addfieldpath =“/ modules / mod_royalslider / fields”>< / fields>

错误消失,字段显示为文本字段.

<fields name="params">
   <fieldset name="basic" addfieldpath="/modules/mod_royalslider/models/fields">

       <field name="title" type="City" label="anythging" description=""   />

   </fieldset>
</fields>