Devise Registration

new.html.haml

.container
  .row
    .col-md-4.col-md-offset-4
      .login-panel.panel.panel-default
        .panel-heading
          %h3.panel-title Sign up
        .panel-body
          %div
            = form_for(resource, as: resource_name, url: registration_path(resource_name)) do |f|
              = devise_error_messages!
              %fieldset
                .form-group
                  = f.label :name
                  = f.text_field :name, class: "form-control", autofocus: true
                .form-group
                  = f.label :email
                  = f.email_field :email, class: "form-control", autofocus: true
                .form-group
                  = f.label :password 
                  - if @minimum_password_length 
                    %em 
                      (
                      = @minimum_password_length 
                      characters minimum)
                    = f.password_field :password, class: "form-control", autocomplete: "off" 

                    = f.label :password_confirmation 
                    = f.password_field :password_confirmation, class: "form-control", autocomplete: "off"
                .form-group
                  =f.fields_for :company do |c|
                    =c.label "Company Name"
                    =c.text_field :name, class: "form-control"
              .actions
                = f.submit "Sign up", class: "btn btn-lg btn-success btn-block"
              %br

          = render "users/shared/links"

registrations_controller.rb

class RegistrationsController < Devise::RegistrationsController
  def new
     build_resource({})
     set_minimum_password_length
     self.resource.company = Company.new
     yield resource if block_given?
     respond_with self.resource
  end
  
  def create
    super
    resource.update_attributes(role: :manager)
  end
 
  private
 
  def sign_up_params
    user_params = [:name, :email, :password, :password_confirmation, [company_attributes: [:name]]]
    params.require(resource_name).permit(user_params)
  end
end

routes.rb

Rails.application.routes.draw do
  devise_for :users, path_names: { registration: 'register'}, controllers: { registrations: "registrations"}
end