Symfony Add bootstrap form-control class

I'm using symfony 2.8, I have created one registration form, I want to add bootstrap form-control class to both password and repeat password form fields.

$builder 
->add('name', TextType::class,array(
    'attr' => array(
        'class' => 'form-control'
    )
))  
-> add('plainPassword', RepeatedType::class, array(
    'type' => PasswordType::class,
    'first_options'  => array('label' => 'Password'),
    'second_options' => array('label' => 'Repeat Password'),
    'attr' => array('class' => 'form-control')
));

Incase of 'name' field its working BUT for password fields the class is not adding. How can I add 'form-control' class for password fields. Any help is much appreciated. Thanks.

There are two ways of doing this. The first is to use options, which will pass the options down to each of the underlying fields:

->add('plainPassword', RepeatedType::class, array(
    'type' => PasswordType::class,
    'first_options'  => array('label' => 'Password'),
    'second_options' => array('label' => 'Repeat Password'),
    'options' => array('attr' => array('class' => 'form-control'))
));

You can also add the class in the first_options and second_options field, like so. This would be useful if you had options that were specific to each field or you wanted to override something from the main options.

->add('plainPassword', RepeatedType::class, array(
    'type' => PasswordType::class,
    'first_options'  => array(
        'label' => 'Password',
        'attr' => array('class' => 'form-control')
    ),
    'second_options'  => array(
        'label' => 'Password',
        'attr' => array('class' => 'form-control-override')
    ),
    'attr' => array('class' => 'form-control')
));

Also, as of Symfony 2.6 it has has built-in Bootstrap form theme support to where you shouldn't have to be adding these classes to all of your fields manually.