gistfile1.rb

### registrations.controller:

class RegistrationsController < ApplicationController
  before_action :set_registration, only: [:show, :edit, :update, :destroy]

  # GET /registrations
  def index
    @registrations = Registration.all
  end

  # GET /registrations/1
  def show
  end

  # GET /registrations/new
  def new
    @registration = Registration.new
    @level = Level.find_by id: params["level_id"]
  end

  # POST /registrations
  def create
    @registration = Registration.new registration_params.merge(email: stripe_params["stripeEmail"],
                                                               card_token: stripe_params["stripeToken"])
    raise "Please, check registration errors" unless @registration.valid?
    @registration.process_payment(stripe_params["stripeEmail"], stripe_params["stripeToken"])
    @registration.save
    redirect_to @registration, notice: 'Registration was successfully created.'
  end

  private
    def stripe_params
      params.permit :stripeEmail, :stripeToken
    end
    # Use callbacks to share common setup or constraints between actions.
    def set_registration
      @registration = Registration.find(params[:id])
    end

    # Never trust parameters from the scary internet, only allow the white list through.
  def registration_params
    params.require(:registration).permit(:level_id, :firstname, :lastname, :phone, :email, :card_token)
  end
end

### registration model

class Registration < ActiveRecord::Base
  belongs_to :level

  def process_payment(email, card_token)
    customer = Stripe::Customer.create email: email,
                                       card: card_token
  
    Stripe::Charge.create customer: customer.id,
                          amount: level.price*100,
                          description: level.name,
                          currency: 'usd'

  end
end

## haml view

= javascript_include_tag "https://js.stripe.com/v2/"
:javascript
  Stripe.setPublishableKey('#{Rails.application.secrets.stripe_publishable_key}');
%section#course-content
  %section#ruby
    %section.detailed-syllabus
      .wrapper-inside
      .container
        .row
        .col-md-4
        .col-md-4
          #flash-messages
          = form_for @registration, html: { class: "basic-grey" } do |f|
            - if @registration.errors.any?
              #error_explanation
                %h2
                  = pluralize(@registration.errors.count, "error")
                  prohibited this registration from being saved:
                %ul
                  - @registration.errors.full_messages.each do |message|
                    %li= message
            .field
              = f.hidden_field :level_id, value: @level.id
            .field
              = f.label :"First Name"
              = f.text_field :firstname
            .field
              = f.label :"Last Name"
              = f.text_field :lastname            
            .field
              = f.label :Phone
              = f.text_field :phone
            .field
              = f.label :Email
              = f.text_field :email            
              = label_tag "Card Number", nil, required: true
              = text_field_tag :card_number, nil, class: "input-block-level", "data-stripe" => "number"
              = label_tag "Card Verification (CVV)", nil, required: true
              = text_field_tag :card_verification, nil, class: "input-block-level", "data-stripe" => "cvv"
              = label_tag "Card Expiration Date", nil, required: true
              = select_tag :exp_month, options_for_select(Date::MONTHNAMES.compact.each_with_index.map { |name,i| ["#{i+1} - #{name}", i+1] }), include_blank: false, "data-stripe" => "exp-month", class: "span2"
              = select_tag :exp_year, options_for_select((Date.today.year..(Date.today.year+10)).to_a), include_blank: false, "data-stripe" => "exp-year", class: "span1" 
            .actions
              = f.submit "Register for The Climb", class: "btn", style: "color: white;background: #c92624;width: 50%;margin-top: 20px;"
              
              
### card-checkout.js

jQuery(function ($) {
  var show_error, stripeResponseHandler;
  $("#new_registration").submit(function (event) {
    var $form;
    $form = $(this);
    $form.find("input[type=submit]").prop("disabled", true);
    Stripe.card.createToken($form, stripeResponseHandler);
    return false;
  });
  
 stripeResponseHandler = function (status, response) {
    var $form, token;
    $form = $("#new_registration");
    if (response.error) {
      show_error(response.error.message);
      $form.find("input[type=submit]").prop("disabled", false);
    } else {
      token = response.id;
      $form.append($("<input type=\"hidden\" name=\"registration[card_token]\" />").val(token));
      $("[data-stripe=number]").remove();
      $("[data-stripe=cvv]").remove();
      $("[data-stripe=exp-year]").remove();
      $("[data-stripe=exp-month]").remove();
      $form.get(0).submit();
    }
    return false;
  };

  show_error = function (message) {
    $("#flash-messages").html('<div class="alert alert-warning"><a class="close" data-dismiss="alert">×</a><div id="flash_alert">' + message + '</div></div>');
    $('.alert').delay(5000).fadeOut(3000);
    return false;
  };
});