db/migrate/20140213053001_add_event_id_at_creation_to_links.rb

@@ -1,15 +1,25 @@

                 class AddEventIdAtCreationToLinks < ActiveRecord::Migration
              

                +  class Link < ActiveRecord::Base; end
              

                +  class Event < ActiveRecord::Base; end
              

                +
              

                   def up
              

                     add_column :links, :event_id_at_creation, :integer, :null => false, :default => 0
              

                 
              

                -    execute <<-SQL
              

                -      UPDATE #{ActiveRecord::Base.connection.quote_table_name('links')}
              

                -      SET event_id_at_creation = (
              

                -        SELECT #{ActiveRecord::Base.connection.quote_column_name('id')}
              

                -        FROM #{ActiveRecord::Base.connection.quote_table_name('events')}
              

                -        WHERE events.agent_id = links.source_id ORDER BY events.id DESC limit 1
              

                -      )
              

                -    SQL
              

                +    Link.all.find_each do |link|
              

                +      last_event_id = execute(
              

                +        <<-SQL
              

                +          SELECT #{ActiveRecord::Base.connection.quote_column_name('id')}
              

                +          FROM #{ActiveRecord::Base.connection.quote_table_name('events')}
              

                +          WHERE events.agent_id = #{link.source_id} ORDER BY events.id DESC limit 1
              

                +        SQL
              

                +      ).first.to_a.first
              

                +      if last_event_id.nil?
              

                +        link.event_id_at_creation = Event.last.id
              

                +      else
              

                +        link.event_id_at_creation = last_event_id
              

                +      end
              

                +      link.save
              

                +    end
              

                   end
              

                 
              

                   def down