application_controller.rb

  before_filter :set_database_for_cluster_stuff

  # SourceSpecific and subclasses (Content, Cluster) take up a lot of space so we want them in
  # their own per-Domain databases. This hook injects the appropriate database connection based
  # on the Domain gleaned from the request so subsequent access (during this request) 
  # will go to the appropriate database.
  def set_database_for_cluster_stuff
    
    config = ActiveRecord::Base.configurations[RAILS_ENV]
    # Get the database name from the Domain
    # everything else (username, password) is the same as the default environment
    connection_parameters = config.merge({'database' => current_domain.cluster_database_name})

    # Content and Cluster are subclasses of SourceSpecific so they'll ge their connections from it
    SourceSpecific.class_eval do
      establish_connection( connection_parameters )
    end

  end