问Yii2中的Dependent下拉列表在更新时丢失值

EN

<?= $form->field($model, 'area_id')->dropDownList(ArrayHelper::map(Department::find()->where(['helpdesk' => 1])->all(),'id','name'),['prompt'=>'Selecione a Área',
        'onchange' => '
        $.post("index.php?r=helpdesk/solicitation/lists&id=' . '"+$(this).val(),function(data){
            $("select#solicitation-type_id").html(data);
        });']) ?>  

<?php
echo $form->field($model, 'type_id')->dropDownList(['prompt'=>'Selecione a Área']);
?>   

public function actionLists($id)
{
    $countType = Type::find()
            ->where(['area_id' => $id])
            ->count();

    $types = Type::find()
            ->where(['area_id' => $id])
            ->orderBy(['name' => SORT_ASC])
            ->all();

    if($countType > 0 )
    {
        foreach($types as $type ){
            echo "<option value='".$type->id."'>".$type->name."</option>";
        }
    }
    else{
        echo "<option> - </option>";
    }

}