Поле мультисписка в Joomla 3

<field name="label_genre"
    type="sql"
    class="inputbox"
    query="SELECT * FROM #__genre"
    key_field="id"
    value_field="title"
    multiple="true"
    label="COM_CREAT_GENRE_LBL"
    description="COM_CREAT_GENRE_DESC">
 
    <option value="">COM_SELECT</option>
 </field>

protected function postSaveHook(JModelLegacy $model, $validData = array())
 {
    if(isset($validData['label_genre']))
    {
        $data['label_genre'] = implode(',', $validData['label_genre']);
    }
 }

protected function loadFormData() 
{
    $data = JFactory::getApplication()->getUserState( 'com_mpc.edit.playlist.data', array() );
    if ( empty( $data ) ) 
    {
        $data = $this->getItem();
    }
    // multiselect
    if($data->label_genre)
    {
        $data->label_genre = explode(',', $data->label_genre);
    }
    return $data;
 }

if (is_array($array['label_genre']))
{
    $array['label_genre'] = implode(',',$array['label_genre']);
 } else if(is_null($array['label_genre'])) 
{
    $array['label_genre'] = '';
 }