How to let user select role upon registration in Facebook-AWD?

Question

I would like to use the plugin Facebook-AWD plugin.

My site would provide two ways of registration (normal and register with Facebook). Users must select their role, ie: buyer and seller.

With normal registration, I can achieve this easily but if my users choose to register with Facebook-AWD they can't select between roles as the plugin is set up to register user with default role:

'role'=>get_option('default_role');

How can achieve this by adding a hook or action or filter to the plugin in order to preserve the plugin core for future update?

public function register_user()
{
    $username = sanitize_user($this->me['first_name'], true);
    $i = '';
    while (username_exists($username . $i)) {
        $i = absint($i);
        $i++;
    }
    $username = $username . $i;
    $userdata = array(
        'user_pass' => wp_generate_password(), 
        'user_login' => $username, 
        'user_nicename' => $username, 
        'user_email' => $this->me['email'], 
        'display_name' => $this->me['name'], 
        'nickname' => $username, 
        'first_name' => $this->me['first_name'], 
        'last_name' => $this->me['last_name'], 
        'role' => get_option('default_role')
    );
    $userdata = apply_filters('AWD_facebook_register_userdata', $userdata);
    $new_user = wp_insert_user($userdata);
    //Test the creation                         
    if (isset($new_user->errors)) {
        wp_die($this->Debug($new_user->errors));
    }
    if (is_int($new_user)) {
        //send email new registration
        wp_new_user_notification($new_user, $userdata['user_pass']);
        return $new_user;
    }

    return false;
}

Answer 1

The plugin offers an entry point for this manipulation:

$userdata = apply_filters('AWD_facebook_register_userdata', $userdata);

So, now it's a matter of you filling up the fictional function in this example:

add_filter( 'AWD_facebook_register_userdata', 'user_role_wpse_87863', 10, 1 );

function user_role_wpse_87863 ( $userdata )
{
    $userdata['role'] = your_way_of_getting_the_role();

    return $userdata;
}

Related:

• About Hooks and Filters

• Actions and filters are NOT the same thing…