new.html.erb

<h2>Sign up</h2>
<div id="stripe_error" class="alert alert-error" style="display:none" >
</div>
<%= simple_form_for(resource, :as => resource_name, :url => registration_path(resource_name), :html => {:class => 'card_form form-vertical' }) do |f| %>
  <h3><%= params[:plan].titleize if params[:plan] %> Subscription Plan</h3>
  <%= hidden_field_tag 'plan', params[:plan] %>
  <%= f.error_notification %>
  <%= f.input :f_name, :autofocus => true %> 
  <%= f.input :l_name %> 
  <%= f.input :email, :required => true %>
  <%= f.input :password, :required => true %>
  <%= f.input :password_confirmation, :required => true %>
  <% if @user.stripe_token %>
    Credit card has been accepted.
  <% else %>
    <div class="field">
      <%= label_tag :card_number, "Credit Card Number" %>
      <%= text_field_tag :card_number, nil, name: nil %>
    </div>
    <div class="field">
      <%= label_tag :card_code, "Card Security Code (CVV)" %>
      <%= text_field_tag :card_code, nil, name: nil %>
    </div>
    <div class="field">
      <%= label_tag :card_month, "Card Expiration" %>
      <%= select_month nil, {add_month_numbers: true}, {name: nil, id: "card_month"}%>
      <%= select_year nil, {start_year: Date.today.year, end_year: Date.today.year+10}, {name: nil, id: "card_year"}%>
    </div>
    <div class="field">
      <%= f.input :coupon %>
    </div>
  <% end %>
  <%= f.hidden_field :stripe_token %>
  <%= f.button :submit, 'Sign up', :class => 'btn-primary' %>
<% end %>

user.rb

class User < ActiveRecord::Base
  rolify
  # Include default devise modules. Others available are:
  # :token_authenticatable, :confirmable,
  # :lockable, :timeoutable and :omniauthable
  devise :database_authenticatable, :registerable,
         :recoverable, :rememberable, :trackable, :validatable

  # Setup accessible (or protected) attributes for your model
  attr_accessible :name, :email, :password, :password_confirmation, :remember_me, :stripe_token, :coupon
  attr_accessor :stripe_token, :current_password, :coupon
  before_save :update_stripe
  before_destroy :cancel_subscription
  
  def update_plan(role)
    self.role_ids = []
    self.add_role(role.name)
    unless customer_id.nil?
      customer = Stripe::Customer.retrieve(customer_id)
      customer.update_subscription(:plan => role.name)
    end
    true
  rescue Stripe::StripeError => e
    logger.error "Stripe Error: " + e.message
    errors.add :base, "Unable to update your subscription. #{e.message}."
    false
  end
  
  def update_stripe
    return if email.include?('@example.com') and not Rails.env.production?
    if customer_id.nil?
      if !stripe_token.present?
        raise "Stripe token not present. Can't create account."
      end
      customer = Stripe::Customer.create(
        :email => email,
        :description => name,
        :card => stripe_token,
        :plan => roles.first.name,
        :coupon => coupon
      )
    else
      customer = Stripe::Customer.retrieve(customer_id)
      if stripe_token.present?
        customer.card = stripe_token
      end
      customer.email = email
      customer.description = name
      customer.save
    end
    self.last_4_digits = customer.active_card.last4
    self.customer_id = customer.id
    self.stripe_token = nil
  rescue Stripe::StripeError => e
    logger.error "Stripe Error: " + e.message
    errors.add :base, "#{e.message}."
    self.stripe_token = nil
    false
  end
  
  def cancel_subscription
    unless customer_id.nil?
      customer = Stripe::Customer.retrieve(customer_id)
      if (!customer.nil?) && (customer.subscription.status == 'active')
        customer.cancel_subscription
      end
    end
  rescue Stripe::StripeError => e
    logger.error "Stripe Error: " + e.message
    errors.add :base, "Unable to cancel your subscription. #{e.message}."
    false
  end
  
  def expire
    UserMailer.expire_email(self).deliver
    destroy
  end
  
end