gistfile2.txt

######### Recuperation du premier collaborateur
>> Collaborator.first
=> #<Collaborator id: 3, firstname: "Madisen", lastname: "Altenwerth", email: "wanda.herzog@schadenbatz.name", created_at: "2010-05-25 10:03:42", updated_at: "2010-05-25 12:27:40", function_id: 5, agency_id: 5>

######### Insertion d un évènement "changement de fonction" sur le collaborateur.
>> HrCollaboratorFunction.create!(:feedback_id => 13, :agency_id => 1, :collaborator_id => 3, :function_id => 2)
=> #<HrCollaboratorFunction id: 1, feedback_id: 13, agency_id: 1, function_id: 2, collaborator_id: 3, created_at: "2010-05-25 12:31:06", updated_at: "2010-05-25 12:31:06">

######### Affichage du premier collaborateur (il a changé de fonction)
>> Collaborator.first
=> #<Collaborator id: 3, firstname: "Madisen", lastname: "Altenwerth", email: "wanda.herzog@schadenbatz.name", created_at: "2010-05-25 10:03:42", updated_at: "2010-05-25 12:31:06", function_id: 2, agency_id: 5>

######################################################################################################

######### Insertion d un évènement "changement de fonction" sur le collaborateur (antérieure en terme de temps)
>> HrCollaboratorFunction.create!(:feedback_id => 1, :agency_id => 1, :collaborator_id => 3, :function_id => 9)
=> #<HrCollaboratorFunction id: 2, feedback_id: 1, agency_id: 1, function_id: 9, collaborator_id: 3, created_at: "2010-05-25 12:31:24", updated_at: "2010-05-25 12:31:24">

######### Affichage du premier collaborateur (il n'a pas changé de fonction vu que la donnée est antérieure à la précédente)
>> Collaborator.first
=> #<Collaborator id: 3, firstname: "Madisen", lastname: "Altenwerth", email: "wanda.herzog@schadenbatz.name", created_at: "2010-05-25 10:03:42", updated_at: "2010-05-25 12:31:06", function_id: 2, agency_id: 5>

hr_collaborator_function.rb

class HrCollaboratorFunction < ActiveRecord::Base
  before_create :callback_function
  
  belongs_to :feedback
  belongs_to :agency
  belongs_to :function
  belongs_to :collaborator

  validates_presence_of :feedback, :agency, :function, :collaborator
  validates_uniqueness_of(:collaborator_id, :scope => :feedback_id)

  def callback_function
    if last_time_function_change(self.collaborator) < self.feedback.feedback_time.to_s
      c = Collaborator.find(self.collaborator_id)
      c.function = self.function
      c.save!
    end
  end

  private

  # last_time_function_change(collaborator)
  # Retrieve feedback_time where the last time
  # which collaborator have change his function
  #
  # collaborator as Collaborator Object
  # return feedback_time in String
  def last_time_function_change(collaborator)
    feedback_time = HrCollaboratorFunction.maximum( 'feedbacks.feedback_time',
                                                :include => :feedback, 
                                                :conditions => {:collaborator_id => collaborator.id}
                                              )

    feedback_time ? feedback_time : "1970-01-01 00:00:00"
  end
end