Handy little class for attaching arbitrary media files

README.md

Handy little class for attaching arbitrary media files (images, audio, video, etc.) to events in a timeline application. It does a couple of nifty things for supporting the varying media types:

The before_post_process method ensures we attempt to generate thumbnails only for images.

The named scopes along with the set_item_type callback gives us a way to pull out media items of a certain type, without having to go down the often more-trouble-than-it's-worth STI path.

media_item.rb

class MediaItem < ActiveRecord::Base
  
  belongs_to :milestone
  has_attached_file :item, :styles => {:thumb => '22x22#', :medium => '300'}

  before_save :set_item_type
  before_post_process :is_image?
  
  validates_presence_of :title
  validates_attachment_presence :item
  
  named_scope :images,  :conditions => {:item_type => 'image'}
  named_scope :audio,   :conditions => {:item_type => 'audio'}
  named_scope :video,   :conditions => {:item_type => 'video'}
  named_scope :other,   :conditions => ['item_type NOT IN (?)', %w{image audio video}]
  
  protected
  
  def is_image?
    self.item_content_type =~ /^image/
  end
  
  def set_item_type
    self.item_type = self.item_content_type.split('/').first
  end
  
end