gistfile1.rb

class Listing < ActiveRecord::Base
  if Rails.env.development?
    has_attached_file :image, :styles => { :medium => "200x>", :thumb => "100x100>" }, :default_url => "404.png"
    validates_attachment_content_type :image, :content_type => ["image/jpg", "image/jpeg", "image/png", "image/gif"]
  else
    has_attached_file :image, :styles => { :medium => "200x>", :thumb => "100x100>" }, :default_url => "404.png",
      :storage => :dropbox,
      :dropbox_credentials => Rails.root.join("config/dropbox.yml"),
      :path => ":style/:id_:filename"
    validates_attachment_content_type :image, :content_type => ["image/jpg", "image/jpeg", "image/png", "image/gif"]
  end
end