Question

We are currently trying to build a Logging functionality for a Rails 3 application. The Log Entry should be stored in the database and provide a link to the logged object. Objects of different classes should be loggable (e.g. tickets, interactions etc.).

How can we store the link to the views of these different objects? We were thinking about associations, but they are statically typed.

Is it possible to store associations to arbitrary objects?

Answer 1

Use polymorphic associations.

class Log < ActiveRecord::Base
  belongs_to :logable, :polymorphic => true
end

class Ticket < ActiveRecord::Base
  has_many :logs, :as => :logable
  def to_label; name; end
end

class Interaction < ActiveRecord::Base
  has_many :logs, :as => :logable
  def to_label; title; end
end

Having a log, to link to it’s associated object’s show path do:

<%= link_to @log.logable.to_label, @log.logable %>