Rails Nested s3_file_field Form

_product_form.html.erb

# Should a new Product with multiple images
# Currently only one of the images is being uploaded into the database, but all images are being uploaded to S3
<%= form_for @product, :html => {:class => 'expanding', multipart: true} do |f| %>
  <%= f.text_area :name %>
  <%= f.fields_for :images, Image.new do |im| %>
    <%= im.s3_file_field :image, :multiple => true, :class => 'js-s3_file_field' %>
    <%= im.hidden_field :id %>
    <%= im.hidden_field :imageable_type %>
    <%= im.hidden_field :imageable_id %>
  <% end %>
  <%= f.submit "Post", class: "btn actions post" %>
<% end %>

images.js

var ready;
ready = function() {
  return $(".js-s3_file_field").each(function() {
    var $parent =  $(this).parent();
    return $(this).S3FileField({
      done: function(e, data) {
        var hidden_field = '<input id="product_images_attributes_0_image_url" name="product[images_attributes][0][image_url]" type="hidden" ' + 'val=' + data.result.url +'>';
        $parent.append(hidden_field);
        return $parent.append("<span>" + data.result.url + "</span>");       
      },
      fail: function(e, data) {
        return alert(data.failReason);
      },
      progress: function(e, data) {
        window.document.title = parseInt(data.loaded / data.total * 100, 10) + '%'
      }
    });
  });
};

product.rb

# This is the object which needs to have many images
class Product < Item
	has_many :comments, as: :commentable
	has_many :likes, as: :likeable
	has_many :images, as: :imageable
	accepts_nested_attributes_for :images
	validates :price, presence: true, :numericality => { greater_than_or_equal_to: 0, less_than_or_equal_to: 1000 }
end

products_controller.rb

class ProductsController < ApplicationController

  def new
    @product = Product.new
    @product.images.build
  end

  def create
    @product = current_user.products.build(product_params)
    if @product.save!
      flash[:success] = "Product created!"
      redirect_to root_path
    else
      @feed_items = []
      render :new
    end
  end

  def show

  end

  private

    def product_params
      params.require(:product).permit(:name, :description, :price, :type, :group_id, images_attributes: [:id, :imageable_type, :imageable_id, :image_url])
    end
end

schema.db

# I've stripped out the unnecessary parts of this file.
# Note that the Product model is part of the Items table with Single Table Inheritance.
# A Product needs to be able to have multiple images

ActiveRecord::Schema.define(version: 20140818030750) do

  create_table "images", force: true do |t|
    t.string   "image_url"
    t.string   "imageable_type"
    t.integer  "imageable_id"
    t.datetime "created_at"
    t.datetime "updated_at"
  end

  create_table "items", force: true do |t|
    t.string   "name"
    t.string   "description"
    t.decimal  "price"
    t.integer  "status"
    t.integer  "user_id"
    t.integer  "group_id"
    t.datetime "created_at"
    t.datetime "updated_at"
    t.string   "type"
    t.string   "image"
  end

  create_table "users", force: true do |t|
    t.string   "email",                  default: "", null: false
    t.string   "encrypted_password",     default: "", null: false
    t.string   "reset_password_token"
    t.datetime "reset_password_sent_at"
    t.datetime "remember_created_at"
    t.integer  "sign_in_count",          default: 0,  null: false
    t.datetime "current_sign_in_at"
    t.datetime "last_sign_in_at"
    t.string   "current_sign_in_ip"
    t.string   "last_sign_in_ip"
    t.string   "confirmation_token"
    t.datetime "confirmed_at"
    t.datetime "confirmation_sent_at"
    t.string   "unconfirmed_email"
    t.datetime "created_at"
    t.datetime "updated_at"
    t.string   "username"
    t.string   "country_code"
    t.string   "subregion_code"
  end
end