Symfony2:将类设置为birthdate小部件生成的选择

Question

在我的表单中,我生成了birthdate字段:

{{form_widget(form.birthdate) }}

生成以下html:

<div id="fos_user_registration_form_birthdate">
    <select id="fos_user_registration_form_birthdate_month"     name="fos_user_registration_form[birthdate][month]">
    <select id="fos_user_registration_form_birthdate_day" name="fos_user_registration_form[birthdate][day]">
    ,
    <select id="fos_user_registration_form_birthdate_year" name="fos_user_registration_form[birthdate][year]">
</div>

我想在select中添加一个类来自定义它们的样式.我怎样才能做到这一点？

PS:如果我加

'attr' => array('class' => 'select-style'),

这个类归于<div id="fos_user_registration_form_birthdate">,而不是选择

Answer 1

{{ form_widget(account_form.birthday.day,{'attr':{'class':'some_class'}}) }}
{{ form_widget(account_form.birthday.month,{'attr':{'class':'some_class'}}) }}
{{ form_widget(account_form.birthday.year,{'attr':{'class':'some_class'}}) }}