_graphic.html.erb

<% @content.medias.build({:key=>"original"}) %>

<%= form_for(@content, :html => { :multipart => true }) do |f| %>
  <div class="field">
    <%= f.fields_for :medias do |media| %>
      <%= media.file_field :file %>
      <%= media.hidden_field :key %>
    <% end %>
  </div>
  <div class="actions">
    <%= f.submit %>
  </div>
<% end %>

_ticker.html.erb

<%= form_for(@content) do |f| %>
  <div class="field">
    <%= f.label :data %><br />
    <%= f.text_area :data %>
  </div>
  <div class="actions">
    <%= f.submit %>
  </div>
<% end %>

content.rb

class Content < ActiveRecord::Base
  belongs_to :user
  belongs_to :kind
  has_many :submissions, :dependent => :destroy
  has_many :feeds, :through => :submissions
  has_many :medias, :as => :attachable
  
  accepts_nested_attributes_for :medias
  accepts_nested_attributes_for :submissions

  #Validations
  validates :name, :presence => true
  validates :kind, :presence => true, :associated => true
  validates :user, :presence => true, :associated => true
  validates :duration, :numericality => { :greater_than => 0 }


  #Easily query for active, expired, or future content
  scope :expired, where("end_time < :now", {:now => Time.now})
  scope :future, where("start_time > :now", {:now => Time.now})
  scope :active, where("(start_time IS NULL OR start_time < :now) AND (end_time IS NULL OR end_time > :now)", {:now => Time.now})
  
  #Scoped relations for feed approval states
  has_many :approved_feeds, :through => :submissions, :source => :feed, :conditions => {"submissions.moderation_flag" => true}
  has_many :pending_feeds, :through => :submissions, :source => :feed, :conditions => "submissions.moderation_flag IS NULL"
  has_many :denied_feeds, :through => :submissions, :source => :feed, :conditions => {"submissions.moderation_flag" => false}

  # Determine if content is active based on its start and end times.
  # Content is active if two conditions are met:
  # 1. Start date is before now, or nil.
  # 2. End date is after now, or nil.
  def is_active?
    (start_time.nil? || start_time < Time.now) && (end_time.nil? || end_time > Time.now)
  end

end

graphic.rb

class Graphic < Content

  #Validations
  validates :duration, :numericality => { :greater_than => 0 }

end

new.html.erb

<% content_for :left_sidebar do %>
<ul>
  <% Content.subclasses.each do |subclass| %>
    <li><%= link_to subclass.model_name.human, new_content_path(:type=>subclass.model_name.singular) %></li>
  <% end %>
</ul>
<% end %>
<%= render 'contents/forms/#{type_will_go_here}' %>

ticker.rb

class Ticker < Content

  #Validations
  validates :duration, :numericality => { :greater_than => 0 }

end